Jump to content
MattR

Full lean under light throttle load

Recommended Posts

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!screengrab.JPG.7375fac70b446d2e53dd951f513c23f1.JPG

BMW E36 G4+ M54B30.pclr

 

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites
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

Share this post


Link to post
Share on other sites

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:

CfiOOUP.png

 

eMjmkcm.png

Share this post


Link to post
Share on other sites
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:

CfiOOUP.png

 

eMjmkcm.png

Thanks Adam, will give it a go tomorrow :)

Share this post


Link to post
Share on other sites
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:

CfiOOUP.png

 

 

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)

 

 

Share this post


Link to post
Share on other sites
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.

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites
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!

Share this post


Link to post
Share on other sites

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? 

943978534_TPSvsMGPlatency.JPG.353b222cf256ad35e33b13dd3da27b62.JPG

 

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

Share this post


Link to post
Share on other sites

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... ;-)

Share this post


Link to post
Share on other sites
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.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×