[KTMasean]

Great so in the closed-loop it does not really matter as the ECU will regulate according to what lambda says, but at higher revs and open-loop it now provides the bike with the fuel it needs in able to make the HP's it was designed for, right?

 

[Alf]

Great so in the closed-loop it does not really matter as the ECU will regulate according to what lambda says, but at higher revs and open-loop it now provides the bike with the fuel it needs in able to make the HP's it was designed for, right?

Well, is a little more subtle... When you modify your bike with more air flow and more fuel flow, in closed loop the ECU have as target lean moistures to reduce emissions and to save fuel. But anyway more air and more fuel is being delivered: so you can expect better driveability and get rid on 2000 to 4000 RPM jerkyness...

If you set the right FPR pressure, when open loop " kicks in" you can expect power and a silly smile. Be cautious for the first and wear a helmet for the second 🤣...

In case of FPR tuning you can expect also better idling. FPR increase is better than bigger injector option when possible.

 

[Alf]

Well ladies & guys: just pay attention because these are pictures that until now were unable to be found with such detail on Google...

First of all we have to distinguish between old style fuel pump and new style ones.

This is oval shaped old style one:

These use standard FPR rated at a fixed pressure. You need to replace the FPR by other one rated at higher pressure to adjust air intake and exhaust mods. The good news: is very easy just remove the fuel pump and free the iron wire clamp and make the FPR replacement. The bad news: you have to purchase the new higher pressure rated FPR.

And this is the new style fuel pump: it occupy less volume inside the tank so more fuel can be carried with a smaller tank. It also features far better sealing gasket and torque plate.

The good news: it features adjustable stock FPR, no need to buy nothing. The bad news: the procedure is slightly more tricky:
Free the plastic enclosure of the fuel pump and retract the pump to make room to pull out the FPR. No need to remove the fuel filter bag.

Insert a thin screw driver 5mm into the FPR hole and make some sort of lever to gently pull out the FPR.

Use a CD pen to make a mark between FPR housing and the screw to see how much additional compression in form or screw turns you put on the inner spring.

Adjust clockwise with an allen key until you reach the desired opening pressure.

This is a safe and budget setup to a FPR. Air density is lower than gas density so to achieve 3,5 BAR opening pressure with gasoline, you have to adjust the screw to open the FPR with 3,2 BAR air. I set mine to 3,8 BAR on gasoline.

Make sure FPR o-ring is in good shape. Reverse mount everything.

For safety reasons, when dealing with fueling systems always disconnect the battery. This is also needed to reset the ECU, and force it to learn again closed loop operation with the new (or adjusted) FPR, air box lid, decat pipe...

The inmediate seat of the pants experience for this setup is better and consistent idling, getting rid of jerkyness from 2.000 to 4.000 RPM (better driveability), faster acceleration transitions and power increase noticeable from 6.000 RPM and up.

I need to get this Dyno proven, but not for me: just for all of you. 😉

Until then, enjoy your ride...

 

[mdharrington]

Been browsing these forums for a while thought I would add up what I have found. Don't mean to hijack the thread, and apologies for straying off topic but I started responding and got too carried away typing.

I have been datalogging this bike with Hptuners MPVI2 via OBD2 adapter. This records internally (with the pro features option)
It does not officially have support for this ECU, but it grabs quite a few PID's through standard OBD2 canbus.

I have also installed an AEM UEGO wideband O2 on a cat eliminator. This particular model also will send its reading over OBD2 via an insert adapter you can see below. That way the data stream is entirely synced up and you can see more precisely what's going on. The AEM wideband I am using is the fastest response time of any wideband you can get with the exception of 1 or 2 others.

I am also running a open top airbox of my own design and a powertronic ecu.

This is one way to properly datalog this bike....but even then this is 1/2 the data I really need to tune this properly. Any more would require some canbus sniffing and likely carrying around a laptop.

Here is the PID's I am pulling. The 1 highlighted in red is from the AEM UEGO Wideband which merges into the OBD datastream.

Basically I can tell you these injectors do have enough flow to get all the way to .8 lambda at 8500 RPM at full load and even richer.
There is no need to ever throw larger injectors in this bike, unless you are significantly increasing airflow way beyond an airbox lid and exhaust.
The problem is in the stock mapping.

Contrary to popular belief, this bike enters open loop all the time.
Closed loop operation happens at part throttle and cruising. But open loop is entered as low as 1500 rpm.
This is in an acceleration state. You can see below. (this was a a blip of the throttle at the lights, as you can see the only changes are map pressure and the narrowbands o2 reading. (The lack of MAF is just a design choice. Ford uses MAF, Dodge uses MAP, GM uses both. It does the same job as a MAF. People seem to think every vehicle requires a MAF but you can go either way, and there are +and - to both.)

At the open loop portion it enters the matrix of its multiple fueling maps, there are at least 7. Some are for component protection (dumping fuel to protect the catalytic converter and O2 sensor) and some are combustion and efficiency tables. These get referenced and out comes your injector pulse.
I haven't fully discovered the logic as to when it enters into acceleration mode, but suffice to say whenever you punch it...you are there.....not just 65% throttle and 8500 RPM as some have stated (powertronic themselves i believe) it is usually accompanied by a fast twist of the throttle.

I can fully back this claim up as well with hard data. In my logs....literally every time I accelerate hard it is in open loop. The other clue is the STFT or short term fuel trims, which are responding to the stock narrowband and completely disable and show zero during all open loop operation, these completely coincide with the open loop states.

What I have found is stock, with no piggyback computer and cat eliminated and open top airbox...the stock ECU and injectors will hit as rich as .8 lambda at 8500 rpm full load. (Load is an OBD specified and inferred parameter but the MAP sensor also shows when you are there).

Where it runs into a little trouble is 5500-7000 RPM where with this combo it can effectively lean out to 1.15 Lambda and above....

Now at low load, a little lean is no big deal. At full load this is very dangerous. And it will happen with stock ecu and airflow mods.

This is effectively where the piggybacks come in. I am dialing in my Powertronic tables now incrementally.

While increasing the fuel pressure should help open loop operation, it can in a lot of vehicles be negated by the LTFT (long term fuel trim)
This can be reset by disconnecting the battery, however the ECU learns the LTFT over time from the info it receives by watching the STFT (STFT is near instantaneous and isnt kept in memory after turned off...you can see it in my logs)
LTFT's job is generally to adjust to changing conditions (wear, lower compression, dirty plugs ect) and is sometimes referenced and multiplied by the open loop tables. I have no reason to believe this is indeed the case for the Duke ECU, but there are some other reasons it may be better not to play with pressure.

A lot of data internal logic that would usually require sensors is inferred by this ECU....engine knock protection being the biggest one. The ECU infers things like octane and combustion limits from the combinations of sensors it has, and the change in fuel pressure could screw that up. There are at least 13 different ignition tables in this ECU....most of them are divided into high octane and low octane categories, which it has to infer from available sensors.

I'm not saying not to do it....just given any other option (like a piggyback) I likely wouldn't touch pressure unless I know there is a table for pressure and a pressure sensor as these modern ECU's are getting pretty advanced logic, and you don't know how a seemingly unrelated value will cascade. Some newer Dodges actually run neural networks instead of certain tables....suffice to say a lot going on in there.

Just FYI, scaling injectors properly is probably the single hardest part of any tuning job as there is way more that just pressure. There usually will be entire tables referencing injector response (not sure in the Dukes case) and almost always you need data supplied by the injector manufacturers unless you literally want to spend $15k on dyno time dialing in the injectors.
The pic below shows a Ford V10 Copperhead ECU injector controls. Each button shown leads to a separate table.

 

[Alf]

Been browsing these forums for a while thought I would add up what I have found. Don't mean to hijack the thread, and apologies for straying off topic but I started responding and got too carried away typing.

I have been datalogging this bike with Hptuners MPVI2 via OBD2 adapter. This records internally (with the pro features option)
It does not officially have support for this ECU, but it grabs quite a few PID's through standard OBD2 canbus.

I have also installed an AEM UEGO wideband O2 on a cat eliminator. This particular model also will send its reading over OBD2 via an insert adapter you can see below. That way the data stream is entirely synced up and you can see more precisely what's going on. The AEM wideband I am using is the fastest response time of any wideband you can get with the exception of 1 or 2 others.
View attachment 53579
View attachment 53583

I am also running a open top airbox of my own design and a powertronic ecu.
View attachment 53584

This is one way to properly datalog this bike....but even then this is 1/2 the data I really need to tune this properly. Any more would require some canbus sniffing and likely carrying around a laptop.

Here is the PID's I am pulling. The 1 highlighted in red is from the AEM UEGO Wideband which merges into the OBD datastream.
View attachment 53580

Basically I can tell you these injectors do have enough flow to get all the way to .8 lambda at 8500 RPM at full load and even richer.
There is no need to ever throw larger injectors in this bike, unless you are significantly increasing airflow way beyond an airbox lid and exhaust.
The problem is in the stock mapping.

Contrary to popular belief, this bike enters open loop all the time.
Closed loop operation happens at part throttle and cruising. But open loop is entered as low as 1500 rpm.
This is in an acceleration state. You can see below. (this was a a blip of the throttle at the lights, as you can see the only changes are map pressure and the narrowbands o2 reading. (The lack of MAF is just a design choice. Ford uses MAF, Dodge uses MAP, GM uses both. It does the same job as a MAF. People seem to think every vehicle requires a MAF but you can go either way, and there are +and - to both.)
View attachment 53581

At the open loop portion it enters the matrix of its multiple fueling maps, there are at least 7. Some are for component protection (dumping fuel to protect the catalytic converter and O2 sensor) and some are combustion and efficiency tables. These get referenced and out comes your injector pulse.
I haven't fully discovered the logic as to when it enters into acceleration mode, but suffice to say whenever you punch it...you are there.....not just 65% throttle and 8500 RPM as some have stated (powertronic themselves i believe) it is usually accompanied by a fast twist of the throttle.

I can fully back this claim up as well with hard data. In my logs....literally every time I accelerate hard it is in open loop. The other clue is the STFT or short term fuel trims, which are responding to the stock narrowband and completely disable and show zero during all open loop operation, these completely coincide with the open loop states.

What I have found is stock, with no piggyback computer and cat eliminated and open top airbox...the stock ECU and injectors will hit as rich as .8 lambda at 8500 rpm full load. (Load is an OBD specified and inferred parameter but the MAP sensor also shows when you are there).

Where it runs into a little trouble is 5500-7000 RPM where with this combo it can effectively lean out to 1.15 Lambda and above....

Now at low load, a little lean is no big deal. At full load this is very dangerous. And it will happen with stock ecu and airflow mods.

This is effectively where the piggybacks come in. I am dialing in my Powertronic tables now incrementally.

While increasing the fuel pressure should help open loop operation, it can in a lot of vehicles be negated by the LTFT (long term fuel trim)
This can be reset by disconnecting the battery, however the ECU learns the LTFT over time from the info it receives by watching the STFT (STFT is near instantaneous and isnt kept in memory after turned off...you can see it in my logs)
LTFT's job is generally to adjust to changing conditions (wear, lower compression, dirty plugs ect) and is sometimes referenced and multiplied by the open loop tables. I have no reason to believe this is indeed the case for the Duke ECU, but there are some other reasons it may be better not to play with pressure.

A lot of data internal logic that would usually require sensors is inferred by this ECU....engine knock protection being the biggest one. The ECU infers things like octane and combustion limits from the combinations of sensors it has, and the change in fuel pressure could screw that up. There are at least 13 different ignition tables in this ECU....most of them are divided into high octane and low octane categories, which it has to infer from available sensors.

I'm not saying not to do it....just given any other option (like a piggyback) I likely wouldn't touch pressure unless I know there is a table for pressure and a pressure sensor as these modern ECU's are getting pretty advanced logic, and you don't know how a seemingly unrelated value will cascade. Some newer Dodges actually run neural networks instead of certain tables....suffice to say a lot going on in there.

Just FYI, scaling injectors properly is probably the single hardest part of any tuning job as there is way more that just pressure. There usually will be entire tables referencing injector response (not sure in the Dukes case) and almost always you need data supplied by the injector manufacturers unless you literally want to spend $15k on dyno time dialing in the injectors.
The pic below shows a Ford V10 Copperhead ECU injector controls. Each button shown leads to a separate table.
View attachment 53582

Yes, your post is some kind off topic. Because this was about a BUDGET way to increase performance in a small displacement engine. But unless we got again "Super's 😘 Red Censorship" 🤣, this is a free topic. So let's understand what you are talking about💸 :

Hptuners MPVI2 pro: 477.75€
VCM scanner suite: 20€
AEM UEGO wideband O2 controller: 293.00€
Powertronic piggyback ECU: 396,21€
Cat eliminator: 90€ + bung + welding or 300€ for the full header in new models + bung + welding
Air box lid: 56€
Dyno runs?

So you are talking about a let's say 1.500€💸 or more customization. 21% cost increase over the MSRP price of a brand new KTM 390: 6.049€.

Unless you are a professional tuner (if you are selling something you should advise people in this forum), this mod is out of reach for the average rider. Don't forget KTM is a global firm that operates in markets where the materials you are proposing are simply unavailable or have an absurd cost compared to the average wage. For example: most asian and south America countries. So FAHGETTABOUDIT.

KTM duke 390 doesn't have OEM onboard knock sensor. Ignition advance maps and fueling maps have been determined by thousands of hours at Mattighoffen dynos bench tests using lab piezoelectric mics designed to "listen" determined frequency: (Knock Frequency = 900,000/(π×0.5 ×cylinder bore diameter )).
Also the KTM duke390 has not fuel density sensor (flex fuel sensor able to detect octane changes in fuel and ethanol % present in fuel) only a fist of Brazilian market (Yamaha YS250 Fazer, Factor 125i, Honda CG160 Flex... all of them low displacement single cilinder bikes) bikes.

Trying to outperform Factory ECU settings with a piggyback ECU and a laptop??? FAHGETTABOUDIT.

Yes open loop "kicks in" in accel transient and wot . This is I always stated constantly and consistently in this topic (and others). The lambda correction system doesn't have enough time to modify injector pulse width during transitions and high RPM.

You state that with decat pipe and open air box the stock ECU reaches 0.8 lambda at 8.500 RPM full load. This is less than 12 AFR, quite on the rich side. But you also state "Now at low load, a little lean is no big deal. At full load this is very dangerous. And it will happen with stock ecu and airflow mods." If the first statement is true, there's no need for FPR tuning or piggyback ECU to avoid lean conditions. What everyone have observed in this bike is that with flow improvements there's need to increase fueling...

Increasing fuel rail pressure improves fuel atomization, and this helps with idling and low rev operation driveability. LTFT in a single cylinder engine is mainly for closed loop operation. LTFT is mainly used to compensate between two cylinder banks (V2, V4, V6, V8... with dual lambda settings), and to compensate for fuel, ignition, and engine problems.

In open loop, the ECU is dumb to the presence of increased fuel rail pressure. No issues. Is a simple yet effective way to get rid of lean moistures after air flow and exhaust upgrades, is not perfect as also piggyback isn't. FPR tuning has more effect on closed loop than piggyback (piggyback ECU doesn't control closed loop), so is more indicated to solve driveability issues.

To properly tune a piggyback ECU you need also Dyno runs.

I'm not saying not to do it, 🤣 but I won't use of a piggyback ECU just to compensate for slight changes in air flow and exhaust flow or just to try to get rid of driveability issues. Just for extreme modifications where the stock ECU has no more room for corrections and street driveability isn't an issue. I understand those who spend zillions on piggyback ECU's and those who sell them, need backup for that kind of decisions ...

 

[mdharrington]

Yes, extremely off topic..sorry
I would delete this thread and move it if I could so as not to take away from the great info you have posted about the fuel pressure mod, so I'll just leave this final reply.

Firstly as far as budget...ya way off.

I happened to have most of this lying around. (with the exception of powertronic and the decat pipe)
If you are paying for the VCM suite FYI you are getting scammed.

Best cheap method for some open loop protection - definitely fuel pressure mod.
For closed loop drivability.....some atomization increase....maybe.

"You state that with decat pipe and open air box the stock ECU reaches 0.8 lambda at 8.500 RPM full load. This is less than 12 AFR, quite on the rich side. But you also state "Now at low load, a little lean is no big deal. At full load this is very dangerous. And it will happen with stock ecu and airflow mods." If the first statement is true, there's no need for FPR tuning or piggyback ECU to avoid lean conditions."

The first statement can still be true, but don't stop reading there.
.8 is a peak. It will generally hover around .92 with mods....so they were likely aiming for a little richer than that in the tables. As stated between 5000-7000 it is absolutely is running lean, and still under full load. Load being a maxed out MAP pressure. Lean under full load meaning engine damage. Higher up the RPM range the table seems to be ok, but the airflow mods are having their greatest impact between 5-7k rpm and running dangerously lean on stock ecu.


"KTM duke 390 doesn't have OEM onboard knock sensor. Ignition advance curves and fueling maps have been determined by thousands of hours at Mattighoffen dynos bench tests using lab piezoelectric mics designed to "listen" determined frequency: (Knock Frequency = 900,000/(π×0.5 ×cylinder bore diameter ))."

If you read what i wrote you will see I indicated the knock protection values are inferred. Meaning there is no knock sensor (all of which are piezoelectric mics) and the octane rating determines which advance table to use. As this bike will be knock limited (meaning max spark advance limited by engine knock before it can achieve optimum power) the inbuilt advance table itself is the knock protection.

"Also the KTM duke390 has not fuel density sensor (flex fuel sensor able to detect octane changes in fuel and ethanol % present in fuel) only a fist of Brazilian market (Yamaha YS250 Fazer, Factor 125i, Honda CG160 Flex... all of them low displacement single cilinder bikes) bikes."

Although it doesnt have a flex fuel sensor, the multiple fuel and spark octane tables in the ECU show it absolutely infers octane through available sensors (o2) and the difference from its expected interaction with the MAP table. Those inferred octane values determine which spark and fuel table the ECU references. As stated there are at least 13 separate spark advance tables (6 high octane, 6 low octane and a few extras)

"FPR tuning has more effect on closed loop than piggyback (piggyback ECU doesn't control closed loop), so is more indicated to solve driveability issues. "

Piggyback does try to control open loop, but FPR and piggyback will both be affected by STFT and LTFT in open loop. They both try to increase fuel, 1 by increased pressure....the other by overriding injector pulse width. They both will have their STFT learned by the LTFT and their effect will be negated back to Lambda. The STFT can be slow to react and you can have initial benefit with both systems while accelerating.

"LTFT is mainly used to compensate between two cilinder banks (V2, V4, V6, V8... with dual lambda settings), and to compensate for fuel, ignition, and engine problems. "

LTFT's are 100% in no way meant for dual bank balance. Each bank has its own STFT and LTFT reading and they have no relationship nor would they need to. They are exactly what they say, long term learned memory from short term fuel adjustments.
Whether or not LTFT affect open loop are dependent on ECU logic.


"To properly tune a piggyback ECU you need also Dyno runs. "

Not to tune AFR.
If I have a target AFR for optimum power you can easily aim for those targets datalog it cell by cell and update the cells in the piggyback, rinse and repeat. I don't think you could get a repeatable measurement on a dyno on the difference between 12 and 12.5 AFR.
Max power is gonna be influenced way more via ignition timing more than fuel. Since the ignition is knock limited, the timing part is easy....take it until just before it knocks and back off 2-3 degrees. Finding knock is a little trickier.

"Trying to outperform Factory settings with a piggyback ECU and a laptop??? FAHGETTABOUDIT."

Factory setting so good that everyone complains about low rpm drivability? Even in a factory tuned vehicle the fist step in tuning it is scaling and verifying the MAP or MAF, and where it rears its ugly head is low rpm drivability. Anyone can tune WOT. Others who have tuned the ECU's complain about the volumetric efficiency tables being off...and this is exactly what causes drivability issues. I agree this cant be totally solved with a piggyback (or fuel pressure mod) with both systems you are modifying fueling but both systems will be fighting STFT once acceleration is out of the way.

"I'm not saying not to do it, 🤣 but I won't use of a piggyback ECU just to compensate for slight changes in air flow and exhaust flow or just to try to get rid of driveability issues. Just for extreme modifications where the stock ECU has no more room for corrections and street driveability isn't an issue. I understand those who spend zillions on piggyback ECU's and those who sell them, need backup for that kind of decisions ..."

These slight changes in flow can push lambda up to 1.2 at 6000 rpm, as measured....
If your fuel pressure mod can handle a 20% increase in fuel then there is nothing to worry about....otherwise some massive injector pulse offset is needed as running lean on a 12.7:1 compression engine is a recipe for disaster.

 

[Alf]

As I told you this is a free topic and any point of view is welcome. No need to delete or move nothing.

Now I better understand your statement... So yes: there's need to enrich after flow mods. Nice info.

Octane rate is a measure that indicates the resistance to auto ignition of a fuel, or in other words resistance to knocking. 95 octane fuel is less resistant (prone to knocking) than 98 octane fuel. Pure ethanol is 120 octane (or more depending on the content % of water). Fuel Octane is determined by refinery. Higher octane fuels are indicated for high compression engines, so they can run more efficiently without Knocking issues. KTM recommend 95 octane fuel for this engine. So using 98 octane fuel as I recommend after a flow upgrade, provides additional safety margin against knocking.

Except for flex fuel vehicles, the only indirect (and cost effective) way for a ECU to know something is wrong with fuel's octane (or also lean AFR, or too advanced ignition, or cooling system malfunction, or intake hot air temperature, or chamber carbon deposit hot spots...) is knock sensor. Flex vehicles are more resistant to adulterated and low quality fuels. This Is why I stated several times in this topic that factory maps are conservative and able to cope with different and extreme conditions. Of course it comes at cost in form performance. Knock sensing system systems and their correction policy's aren't also perfect. The only perfect ECU is SAAB ION SENSING.

Tuning just for AFR doesn't grant max power nor efficiency. It only grants no lean or rich issues. To tune a vehicle you just need a Dyno (able to deal with partial loads to determine ignition advance maps). Beware of "self learning" piggyback ECU's that use stock narrow band inputs. If you don't have means for that, do FPR tuning. I don't mind STFT at closed loop.

Factory settings have to comply with emissions regulations and yes, they kind of suck. But the way factory comply with that is optimal. As a result stock engine run most of the time at lean side but they are designed with this in mind. If you read carefully my recipe I work to minimize knocking issues by all means available. FPR tuning can arrive to 20% enrichment on this bike. But my calculations lead me to estimate that a 15% increase (4 Bar FPR) @ injector duty cycle with my setup is more than enough to avoid knocking with the stock ECU.

 

[mdharrington]

As I told you this is a free topic and any point of view is welcome. No need to delete or move nothing.

Now I better understand your statement... So yes: there's need to enrich after flow mods. Nice info.

Octane rate is a measure that indicates the resistance to auto ignition of a fuel, or in other words resistance to knocking. 95 octane fuel is less resistant (prone to knocking) than 98 octane fuel. Pure ethanol is 120 octane (or more depending on the content % of water). Fuel Octane is determined by refinery. Higher octane fuels are indicated for high compression engines, so they can run more efficiently without Knocking issues. KTM recommend 95 octane fuel for this engine. So using 98 octane fuel as I recommend after a flow upgrade, provides additional safety margin against knocking.

Except for flex fuel vehicles, the only indirect (and cost effective) way for a ECU to know something is wrong with fuel's octane (or also lean AFR, or too advanced ignition, or cooling system malfunction, or intake hot air temperature, or chamber carbon deposit hot spots...) is knock sensor. Flex vehicles are more resistant to adulterated and low quality fuels. This Is why I stated several times in this topic that factory maps are conservative and able to cope with different and extreme conditions. Of course it comes at cost in form performance. Knock sensing system systems and their correction policy's aren't also perfect. The only perfect ECU is SAAB ION SENSING.

Tuning just for AFR doesn't grant max power nor efficiency. It only grants no lean or rich issues. To tune a vehicle you just need a Dyno (able to deal with partial loads to determine ignition advance maps). If you don't have means for that, do FPR tuning. I don't mind STFT at closed loop.

Factory settings have to comply with emissions regulations and yes, they kind of suck. But the way factory comply with that is optimal. As a result stock engine run most of the time at lean side but they are designed with this in mind. If you read carefully my recipe I work to minimize knocking issues by all means available. FPR tuning can arrive to 20% enrichment on this bike. But my calculations lead me to estimate that a 15% increase (4 Bar FPR) @ injector duty cycle with my setup is more than enough to avoid knocking with the stock ECU.

I agree with all of that 100% with a slight caveat on dyno tuning and AFR.
Most NA engines out there will have max power somewhere around lambda .85 +- .04 considering the engine.
On a typical 350 hp engine on a dyno, dropping lambda from 1.0 to 0.9 usually results in a difference of 1-3 ft/lb of torque gain.
All I am saying is that on a 43hp engine the toque increase would be almost undetectable and unrepeatable on the dyno between .87 and .82 lambda. So yes you could tune to find the sweet spot, but your better just erring on the rich side a tiny bit and calling it a day. Drastically more power comes out of timing.

The other thing usually accomplished on the dyno is finding MBT. This is an increase in timing until either knock occurs, or torque decreases. If knock occurs before torque decreases....the engine is knock limited. With our high compression engines this is guaranteed to be the case unless you were to use some high quality racing fuel.

Its a hard and inconvenient limit in the fact that there is missing torque you cannot access on regular fuel, but it makes tuning easy. Find knock and back off as many degrees as you are comfortable with and you are literally at the peak torque (you've allowed)
Not having a knock sensor likely means they significantly erred on the side of caution as far as the tables are concerned and there is some torque to be had, but it better be accompanied with some extra fuel.

"The only perfect ECU is SAAB ION SENSING"
You mean the system Harley Davidson uses
That has been around for a while in quite a few vehicles...mercedes does it with dual spark plugs, one as the ion sensor the other as the spark source and then alternating between them (i think in the older gen v12's.) It has big problems at low load and although it is pretty promising its not as revolutionary (currently) as it is usually described. Hence the low adoption. I like the idea, but knock sensors can be pretty good as long as the filtering is set properly.

The revolutionary part of ion sensing is calculating cylinder pressure. Right now that is done by the OEM with some pretty specialized equipment and expensive that can survive the combustion process in a test lab. Your goal through ignition advance is highest cylinder pressure without knock at around +20degrees TDC. (con rod/crank dependent). The ion sensing could potentially give you this data without a dyno and open up closed loop ignition tuning. To date no one has implemented this properly that I know of.

 

[Alf]

I will buy a piggyback ECU when it features Ion Sensing. Ion Sensing was developed by Linköping University at Sweden and Saab. Ville Vartiovaara is my hero: he did ion sensing for real time ignition tuning. Saab(Delphi) sold it to GM, and Harley Davidson. So further development become crap...

In a Harley it makes sense using Ion Sensing because backwards cilinder runs less refrigerated (more prone to knocking). So you have two cilinder running at different ignition timing and AFR.

Ion Sensing mirroring is like an onboard Dyno. Inicially It was used for knock sensing but later development made possible using it for MBT detection, on board, real time, cilinder to cilinder.

We have ended aiming a future with umbilical vehicles because ion sensing was not adopted by the whole industry.

And it used plasma jet discharge. So no problem with low load. Plasma jet is also big deal: you can achieve Maximum Brake Torque with conservative ignition timing. Faster flame propagation due to initial combustion kernel 300 times bigger than in a common spark plug.

Until then, with civilized flow improvements in a small displacement engine: I choose budget FPR tuning. As you said absolut precision defining ideal AFR in this kind of engine is not such a big deal...

 

[mdharrington]

And I would buy another piggyback if it had ion sensing
There is a bunch of DIY guys playing with it on home built ecu’s….very technical to calibrate from what I gather.

Ion Sense - rusefi.com

 

[Alf]

And I would buy another piggyback if it had ion sensing
There is a bunch of DIY guys playing with it on home built ecu’s….very technical to calibrate from what I gather.

Ion Sense - rusefi.com

Interesting!
I have designed and tested several prototypes of plasma jet ignition. Is the ideal complement for ion sensing: plasma jet discharge takes only 2 to 6 ms so it is very precise timing and the rest of the combustion time window can be used for ion sensing mirroring between spark plug electrodes...

Here's a couple of videos of early prototypes I made:

Nice stuff...

 

[Kevin Armstrong]

Hello Alf, grateful for your guide, I'm riding a 2021 Svartpilen, motor same as KTM 390, also paid/downloaded repair Manual; currently researching cure for lean and jerky fuelling on the Euro-5 2021 model. This spoils ride in urban traffic, on open road at high rpm bike is fine. Working through your numbers, appears that injection pressure is higher than the 3.0 Bar you quote; on the later bike already 3.2...3.7 Bar, possibly to improve emissions and fuel atomisation? Intend stripping the tank and pump, what extra pressure do you suggest to cure low speed lean running? Boosterplug is not made for bikes after 2019, shame.

 

[Alf]

Hello Alf, grateful for your guide, I'm riding a 2021 Svartpilen, motor same as KTM 390, also paid/downloaded repair Manual; currently researching cure for lean and jerky fuelling on the Euro-5 2021 model. This spoils ride in urban traffic, on open road at high rpm bike is fine. Working through your numbers, appears that injection pressure is higher than the 3.0 Bar you quote; on the later bike already 3.2...3.7 Bar, possibly to improve emissions and fuel atomisation? Intend stripping the tank and pump, what extra pressure do you suggest to cure low speed lean running? Boosterplug is not made for bikes after 2019, shame. View attachment 54051

Hello Kevin. That is a good point.

You have to distinguish between fuel line pressure and fuel pressure regulator opening pressure.

Once the FPR opens the fuel pump is still capable to build some additional pressure on the line.

My experience is that 2019 and up KTM 390 engines FPR opening pressure is 3.0 Bar, but fuel line can reach up to 3.5 Bar.

In the service manual they specify a line pressure interval between 3.2 and 3.7 Bar as a normal operation range. This is because some factors as fuel pump wearing over time, battery voltage, fuel density (ethanol content, temperature...) have an impact on fuel line (rail) pressure.

If you want to get rid of low rpm jerkyness set your FPR to open at 3.5 Bar (using compressed air). If you do some additional intake and exhaust flow mods, go up to 4.0 Bar FPR opening pressure.

Your bike have adjustable FPR so you can use a trial error approach until you get driveability improvement...

Does your service manual say something about the injector flow rate???

Regards.

 

[Kevin Armstrong]

Even more useful Alf, thanks. The factory special tool test tubing rig has a restrictor nozzle bleed off, presumably to mimic an injector, pump capacity is always excess to throttle body demand (my ultralight aircraft external pump shifts 130 litres per hour, but demand average 8l/hr). That system has an external Fuel Pressure Regulator with gauge in the tank return line, to keep closed until 3 bar is reached. On a motorcycle you could add a small FPR with separate return line to tank, but that would merely be 'short cut' by the internal tank Relief Valve, bleeding back to tank before it leaves out to the filter. More thought needed 🤔

 

[Alf]

Even more useful Alf, thanks. The factory special tool test tubing rig has a restrictor nozzle bleed off, presumably to mimic an injector, pump capacity is always excess to throttle body demand (my ultralight aircraft external pump shifts 130 litres per hour, but demand average 8l/hr). That system has an external Fuel Pressure Regulator with gauge in the tank return line, to keep closed until 3 bar is reached. On a motorcycle you could add a small FPR with separate return line to tank, but that would merely be 'short cut' by the internal tank Relief Valve, bleeding back to tank before it leaves out to the filter. More thought needed 🤔

In fact Kevin, it would be great using an external FPR and gauge setup. But you first will need to pull out the stock FPR.

This way you don't need to disassemble the fuel tank and pump assembly each time you want to try a different FPR setup...

You can do the tests on the bike to determine the FPR setup for optimal engine behavior and AFR. Once you have it, you can disassemble the external FPR and attach it to the compressed air pressure gauge and measure the opening pressure.

Then you can set the the stock FPR to the same opening pressure and install it. So you will have the bike back to stock...👍🏻

Does your service manual say something about the injector flow rate??? I need to confirm that info...

Regards!

 

[Mauro]

Well ladies & guys: just pay attention because these are pictures that until now were unable to be found with such detail on Google...

First of all we have to distinguish between old style fuel pump and new style ones.

This is oval shaped old style one:
View attachment 53532
These use standard FPR rated at a fixed pressure. You need to replace the FPR by other one rated at higher pressure to adjust air intake and exhaust mods. The good news: is very easy just remove the fuel pump and free the iron wire clamp and make the FPR replacement. The bad news: you have to purchase the new higher pressure rated FPR.

View attachment 53531
And this is the new style fuel pump: it occupy less volume inside the tank so more fuel can be carried with a smaller tank. It also features far better sealing gasket and torque plate.
View attachment 53534
View attachment 53533
The good news: it features adjustable stock FPR, no need to buy nothing. The bad news: the procedure is slightly more tricky:
Free the plastic enclosure of the fuel pump and retract the pump to make room to pull out the FPR. No need to remove the fuel filter bag.
View attachment 53535
Insert a thin screw driver 5mm into the FPR hole and make some sort of lever to gently pull out the FPR.
View attachment 53536
Use a CD pen to make a mark between FPR housing and the screw to see how much additional compression in form or screw turns you put on the inner spring.
View attachment 53537
Adjust clockwise with an allen key until you reach the desired opening pressure.
View attachment 53538
This is a safe and budget setup to a FPR. Air density is lower than gas density so to achieve 3,5 BAR opening pressure with gasoline, you have to adjust the screw to open the FPR with 3,2 BAR air. I set mine to 3,8 BAR on gasoline.

Make sure FPR o-ring is in good shape. Reverse mount everything.

For safety reasons, when dealing with fueling systems always disconnect the battery. This is also needed to reset the ECU, and force it to learn again closed loop operation with the new (or adjusted) FPR, air box lid, decat pipe...

The inmediate seat of the pants experience for this setup is better and consistent idling, getting rid of jerkyness from 2.000 to 4.000 RPM (better driveability), faster acceleration transitions and power increase noticeable from 6.000 RPM and up.

I need to get this Dyno proven, but not for me: just for all of you. 😉

Until then, enjoy your ride...

Thank you Alf for sharing your experience! Mauro

 

[Just_bright]

Hey guys. Long time rider first time poster. I've been reading around on the forum and I finally decided to just throw in a "hello all from Southern California" as well as my own smelly arsehole opinion.

To Alf: (and regarding his budget/not-budget list and explanations) .... BRAVO.

I think a lot of you guys are spending too much time running around in mental circles with this stuff. The best part about cheap tricks is, well, they are cheap and anyone can try them out.

I really appreciate the new rider who wants to make his bike go vrooom all of a sudden but the best thing one can do is something my old coach taught me when I was coming up as a kid and it's the cheapest mod/performance trick of all
#1 Ride, ride, ride (on a track preferably but a well known stretch of twisty will do just fine too)

#2 Paper and Pencil (Journal) to jot down every little detail your little butt feelers tell you about what your bike is doing.

-Applying the above process to simple tweaks like Mr. Alf has shared are the best and most affordable (AND MEANINGFUL) way to judge how they work for your setup and skill level.

I personally was never much into the inner wizardry of the technicians around me, but because of the understanding I learned from my Sweaty-Butt-Monologues as a kid racer, I was able to make sense of all the various parameters that affect power gains pretty well.

Spending time wrenching on the bike is what its all about. I don't think there is just a perfect setup that any new bike owner will come across on a forum of his new bike that can tell him what to buy and who to believe. Get out there with your Ass, Journal, and toolbag and start playing around with it all and enjoy the freaking process of discovery while your at it!

Then all that money you save you can hand over to Ohlins anyways haha. Cheers guys.

 

[Just_bright]

FYI I run the 4,0 bar pressure regulator valve on my 2019. PT, Full Custom Titanium Polished and Ported exhaus.t Coober Filter Box. Bosche High Flow injector, NGK plug, (cat delete) and a lot more.

Fast. Unregistered. Cop Magnet and eager to tease.

 

[Just_bright]

Cant remember where I found the valve but figured the timing and fuel would be handled in WOT by the PT map so I went big. Pretty sure it was for an R1 or GSXR. Dude messured it for me before I bought it to make sure it would fit.

 

[1jzsupra]

Honestly, I higher doubt you need a FPR if you are running the larger injector. I had to pull an absolute mountain load of fuel after installing mine.