Full lean under light throttle load

[MattR]

Managed to take the car (e36 with M54B30, E36 G4+ plugin) for a coupe of logging runs this weekend, and have noticed that irrespective of engine RPM it goes full lean at low throttle % and also while starting to accelerate. It's making it rather difficult to start to tune the fuel maps - is this likely to be related to the Acceleration enrichment tables? This is my first attempt at tuning an engine, am a little lost as to where to start. It's still running  on the basemap E36 tune, excuse the messy state of the current maps.

Thanks!

BMW E36 G4+ M54B30.pclr

 

[Adamw]

It is better to attach the actual log file rather than a screenshot, cant tell much from what is shown above.

[krohelm]

Yeah, tough to see much without a log, but some of this looks really familiar to me.  (everything looks like a nail, right?)  2 cents:

1. You have Overrun Fuel Cut set to 1% TP.  If your foot is light on the gas and the engine is warm you'll see "very lean."  That part is "by design" and like an OEM system.  If your TP sensor is good, you should consider using a TP lower than 1% for fuel cut.  I have ITB's, but my TP sensor is well-configured.  I use 0.1% throttle for overrun fuel cut.  At 1% it surges and bucks really terribly while in slow traffic in my particular engine (TP ends up at around 0.2-0.4% in those situations for my engine.  ymmv.)
2. Accel Enrich was necessary for me to smooth out those spikes you see when you stab into the throttle.  I was unable to achieve a repeatable tune without carefully configuring accel enrich.
   Get a low RPM cell (like 1000rpm) in good shape with steady state (find a hill and go up in 5th at 30mph WOT while logging haha) then do idle throttle stabs at 1000rpms while tuning out the lean spike with your accel enrich.
   This is what I did with my VE tune, but you're on Traditional fueling.  Not sure how much different it may be to get your accel enrich roughed in.

Good luck, and post logs!  You'll get sorted.  :-D

[MattR]

23 minutes ago, krohelm said:

Yeah, tough to see much without a log, but some of this looks really familiar to me.  (everything looks like a nail, right?)  2 cents:

1. You have Overrun Fuel Cut set to 1% TP.  If your foot is light on the gas and the engine is warm you'll see "very lean."  That part is "by design" and like an OEM system.  If your TP sensor is good, you should consider using a TP lower than 1% for fuel cut.  I have ITB's, but my TP sensor is well-configured.  I use 0.1% throttle for overrun fuel cut.  At 1% it surges and bucks really terribly while in slow traffic in my particular engine (TP ends up at around 0.2-0.4% in those situations for my engine.  ymmv.)
2. Accel Enrich was necessary for me to smooth out those spikes you see when you stab into the throttle.  I was unable to achieve a repeatable tune without carefully configuring accel enrich.
   Get a low RPM cell (like 1000rpm) in good shape with steady state (find a hill and go up in 5th at 30mph WOT while logging haha) then do idle throttle stabs at 1000rpms while tuning out the lean spike with your accel enrich.
   This is what I did with my VE tune, but you're on Traditional fueling.  Not sure how much different it may be to get your accel enrich roughed in.

Good luck, and post logs!  You'll get sorted.  :-D

 

Sorry guys, thought I had attached the log as well - here we go

 

Friday 22-11.llg

[MattR]

On 11/24/2018 at 2:26 PM, Adamw said:

It is better to attach the actual log file rather than a screenshot, cant tell much from what is shown above.

Log attached  Friday 22-11.llg

[Adamw]

If you mean the lean spikes below every time you move the throttle, then yes I would say that is accel enrichment related.

I would change the "accel hold" to 6 events and bump the load correction up a bit.  Try something like this:

 

[MattR]

On 11/29/2018 at 2:24 PM, Adamw said:

If you mean the lean spikes below every time you move the throttle, then yes I would say that is accel enrichment related.

I would change the "accel hold" to 6 events and bump the load correction up a bit.  Try something like this:

 

Thanks Adam, will give it a go tomorrow

[MattR]

On 11/29/2018 at 2:24 PM, Adamw said:

If you mean the lean spikes below every time you move the throttle, then yes I would say that is accel enrichment related.

I would change the "accel hold" to 6 events and bump the load correction up a bit.  Try something like this:

 

 

Have implemented the changes, and it has made an improvement, though has not eliminated the condition. It does still spike full lean but doesn't seem to stay lean for quite as long.

Log 2018-12-1 3;42;34 pm.llg

 

Would increasing the Sensitivity % be of any benefit in this situation? Still trying to figure out how all the enrichment settings work together (slow learner sorry)

 

 

[motomattx]

Are you certain that your injector dead times are correct?

[MattR]

2 hours ago, motomattx said:

Are you certain that your injector dead times are correct?

To the best of my knowledge, yes. There doesn't seem to be a whole lot of data around for the OEM M54B30 injectors, but what info I have come across gives me 1.03ms @ 14v, which is what I'm currently using.

[Adamw]

Its not a deadtime problem, in the lean areas you have 6-10ms of pulsewidth in the screenshot above and constant battery voltage, even if the deadtime was out by 50% its going to make FA difference.

 

16 hours ago, MattR said:

Would increasing the Sensitivity % be of any benefit in this situation? Still trying to figure out how all the enrichment settings work together (slow learner sorry)

Yep, I would try that next.  I would also try more accel hold (try 12events) if sensitivity doesnt get it.  Also turn CLL off as that is having an impact as well.

[MattR]

7 minutes ago, Adamw said:

Its not a deadtime problem, in the lean areas you have 6-10ms of pulsewidth in the screenshot above and constant battery voltage, even if the deadtime was out by 50% its going to make FA difference.

 

Yep, I would try that next.  I would also try more accel hold (try 12events) if sensitivity doesnt get it.  Also turn CLL off as that is having an impact as well.

I did spot CLL was on while trawling through the settings late last night. Have now disabled it until I get my head around whats happening here.

 

Awesome, thanks again!

[MattR]

Looking at some of the logs I'm noticing a slight delay between the TPS moving and a corresponding change in MAP - could this be a contributing factor in the

throttle hesitation I'm experiencing? 

 

Have bumped Accel Sense up to 70 & Accel Hold to 10 with only a marginal improvement to the issue I'm encountering.

 

Thanks again

 

BMW E36 G4+ M54B30.pclr

Log 2018-12-11 6;38;24 pm.llg

[krohelm]

You might want to turn off accel enrich & spend a little more TLC time on your fuel?  I went looking for a problem in your fuel table around ~85kpa at 2700-2800rpm, and you've got a canyon right exactly there that is 14% lower than the values of the cells on either side (11-12% absolute).  Wildly configured accel enrich can throw your fuel table totally wonky (ask me how I know), it's best to get your fuel table right and then fix dynamics like dumping fuel when stabbing the throttle.

Modelled fuel mode is great too... ;-)

[MattR]

On 12/12/2018 at 6:39 PM, krohelm said:

You might want to turn off accel enrich & spend a little more TLC time on your fuel?  I went looking for a problem in your fuel table around ~85kpa at 2700-2800rpm, and you've got a canyon right exactly there that is 14% lower than the values of the cells on either side (11-12% absolute).  Wildly configured accel enrich can throw your fuel table totally wonky (ask me how I know), it's best to get your fuel table right and then fix dynamics like dumping fuel when stabbing the throttle.

Modelled fuel mode is great too... ;-)

Yeah,  I understand that the rubbish fuel table isn't helping things. I've been having an issue with Mixture Map not updating after correcting the calibration table for Lambda 1 so have been using Quick trim whilst reviewing logs. As you can imagine I'm not getting the best results as I'm changing a table value based on one sample instead of the aggregate value that mixture map applies.

[MattR]

Final update on this one - took the car out with someone a lot more experienced with Link & tuning than I at the start of last month to iron out the fuel & ignition maps.

He managed to get the tune reasonably good in most places, but couldn't fix the lean spike on accel issue, and  also was unable to get the idle AFR any leaner than 13:1, we were bottoming out the injector if we tried to remove any more fuel. Compression tested the engine (came back averaging 208psi on all 6 cylinders) so added a vacuum gauge to discover we were only seeing 12 inHg at idle. Analysed a few logs and saw that even on decel the map never ventured much below 50kPa.  After much to-ing and fro-ing I narrowed it down to the exhaust cam being too far advanced leading to quite a bit of overlap on what are fairly mild cams (244º, 9.7mm lift intake & 240º, 9mm lift exhaust). My theory is the lack of vacuum at low load was preventing the fuel pressure reg from opening the return line fully, leaving higher than usual rail pressure at low load and consequently overfuelling. I don't have access to a dial gauge or degree wheel so opted instead to swap the M54 Vanos exhaust cam for an M50 non Vanos one that came from the engine I pulled to do the B30 swap in the first place. Post cam swap the engine now goes beyond 80kPa on decel, idles around 65kPa and no longer lean spikes when throttle is initially applied. Very happy!

On 12/2/2018 at 9:19 AM, Adamw said:

Its not a deadtime problem, in the lean areas you have 6-10ms of pulsewidth in the screenshot above and constant battery voltage, even if the deadtime was out by 50% its going to make FA difference.

 

Yep, I would try that next.  I would also try more accel hold (try 12events) if sensitivity doesnt get it.  Also turn CLL off as that is having an impact as well.

Adamw thanks very much for your input on chasing this issue down.