E38 PE Issue. Lean 2.1 Seconds. Can we solve this?

[BigDaddyCool]

I sent a message off to Chris, never got a reply.

E38. Jump into PE random lean spike between 2.1 to 2.3 seconds.

Questions for others:

1. Have people only noticed this on pre-2010 vehicles? (the they have a much weaker fuel pump and settings).
2. Has anyone noticed this on the stock cam or is it only after a cam swap?
3. Has anyone noticed anything? pressure drops, voltage drops....
4. How much timing is everyone running.....
5. Only been after you've pulled the fuel rail up/changed injectors? I even replaced my original o-rings.... didn't help.

I don't know what else there is to ask. I feel like maybe HPTuners is missing some stuff for the E38's that could fix this...... some missing features somewhere, or time limits etc.

It doesn't seem to have anything to do with how peoples cars are setup, maf or mafless etc........ before I did my cam change to a LS9 from the stock L76 there was a very minor leaning out at 4800rpm 6%..... that I could never get rid of. But now with the cam change it's massive right on 2.1 seconds any rpm after PE engages. Is there a PE bug or setting we are missing?

It doesn't appear to be injector timing, VE related......... could be voltage, mis fire, power loss, transients (maybe some setting we are missing)...... we cannot log on the scanner when transients start/end properly.

It's a very big issue......... basically you cant do a single dyno run...... and it risks engine safety.

[realcanuk]

I remember I used to have a lean spike entering PE. I will try and find in my notes what changes I made that fixed it. It was 3 or 4 years ago and I don't remember exactly. Possibly something I changed in transients, but I am not sure. I will update when I have some time to look.

[Pekka_Perkeles]

I sent a message off to Chris, never got a reply.

This is tuning issue.

E38. Jump into PE random lean spike between 2.1 to 2.3 seconds.

Questions for others:

1. Have people only noticed this on pre-2010 vehicles? (the they have a much weaker fuel pump and settings).

Yes.

Zero out prediction coefficients.

Don't forget to give feedback in this thread when you've tried as suggested above, thank you. :-)

[Vasquezz1228]

Im having trouble even getting into PE on the e38. I have set tps to 5% and still wont go into pe. Any one have this issue before?

[BigDaddyCool]

This is tuning issue.


Yes.

Zero out prediction coefficients.

Don't forget to give feedback in this thread when you've tried as suggested above, thank you. :-)

FAIL

Looks like I'm on my own. I would list every variation of things I've tried but it would take forever.

No to transients, no to dynamic anything, no to timing or ve table or maf hz etc, no to fuel injectors, no to traction or torque management....... JUST NO NO NO.

----------

I get a lean spike from a stand still, it settles and then returns on that 2.1 second mark..... they are obviously the same issue. It is no transient..... you could add thousands of percent or reaction time or evap and get no solution.

It's like the fuel just isn't there, and despite what the scanner reports, perhaps the pump or rail is loosing pressure........ for a split second.

Mines a 2009 model, the fuel pressures look crap compared to 2010+ models....... and then there's a calculation on how it deals with low/normal/high pressure switching.

I could set my transients at 0 everything for delay, through 3000% at my impact or whatever...... it still lags. It's like the whole car lags.... I do have a massive stereo but even it has a 2 farad capacitor.

-- I'm thinking I might rig my tech 2 up and watch the fuel pump on a run maybe.....

[Chris@HPTuners]

post a log? is injector pulse width changing? commanded AFR? airflow? fuel pressure? PE is a very simple thing...

[BigDaddyCool]

post a log? is injector pulse width changing? commanded AFR? airflow? fuel pressure? PE is a very simple thing...

I'll throw in a couple of logs. And attach my base tune. The logs have varying changes to the tunes they were run off....... but all produce the same result. Just look for the wot runs.... mid run you'll see it. Should be enough info there to give you an idea.

I'm starting to think it's either fuel pump settings...... or a flow rate issue.

[realcanuk]

Just an idea but I would try lowering the PE delay and the PE throttle/pedal enable number just to see if it has any effect.

[Chris@HPTuners]

i would check fuel pressure, everything else in the log looks ok to me. AFR Cmd, airflow, airmass, MAP, injpw all looks stable when the leanout occurs

[GHuggins]

Chris, a lot of people have this issue - this vehicle from what I've been reading seems to be the worst, but I think it's this controller in particular as other vehicles are effected... There was an entire thread devoted to it a while back - lean out 2 seconds after entering PE or something like that?

[BigDaddyCool]

The last thing I'm about to try is to run full pressure 400kpa on the pump and increase fuel pump voltage required. This will either fix my wot lean spike and my pe 2.1 second spike or it will change nothing.

It would be nice if there was the ability in the scanner to watch the fuel pump to see what 'mode' it's classed as being in. Upper/lower fuel flow etc so I know what pressure it's varying between.

[BigDaddyCool]

Didn't work. It's exactly like PE drops out without dropping out. It's some sort of bug somewhere...... maybe a requirement for staying in PE is being set off somewhere we cant see ...... It's BS. I'm like spitting chips over this issue. There are better things to be looking at. No point putting the car on the dyno when the fuel cuts out mid run .......

[SSUte01]

Try full open loop as a test with the OL multipliers equalling your desired EQ Ratio in PE i.e. if you're targeting 1.16 in PE, set the various OL mults to 1.16 in that IVT/MAP/InjTemp etc or alternatively just set the min EQ Ratio to your desired PE ratio temporarily as a test (means it will be richer than stoic everywhere but it will allow you the see that your fuel system can keep up and it's not a transient thereby taking PE out of the equation. I'm on a different computer so I can't view HPT but I think that setting is under Fuel - General (or Open/Closed Loop) --> min EQ ratio or something similar.

[SSUte01]

There was a big arse thread about this a few years back as mentioned above and I don't recall any meaningful solution. I personally haven't noticed this phenomena - I will check on a 07 E38 that I can access readily. I never noticed when I first tuned it, but I'll re-check. FWIW, I've never noticed it on numerous E38s or E67s but perhaps I haven't analysed closely enough

[BigDaddyCool]

I'll try the open loop EQ test........ I've got a Tech 2 on hand so I'll check what I can with that and log a run with it if can monitor the fuel pump etc while doing it.

I'll go around the engine 'again' and look for vaccume leaks. The injectors o-rings were replaced, I tightened all the sparkies, replaced the intake manifold o-rings, the exhaust manifold is good..... Like either there is a leak at the back of the manifold maybe with the brake booster hose? ..... (literately the one thing I think it could be outside something else).

If I leave the car for a few days sometimes when I've come back to it the brakes have been rock hard........ which would suggest a vac leak to me...... Problem is I keep going back to check it all, it's all fine.

Like I can command much richer AFR's to cover this issue but it's not the solution.

[GHuggins]

Try a test with transients completely disabled via their master switch too...

[Niemer]

I asked this question 4 years ago and still have no solution. People smarter than I seem to have gotten onto something towards the end of the thread below.

https://www.hptuners.com/forum/showt...pot-during-WOT

TLDR; this happens regardless of hardware, the only thing that remains common is the e38 and leaving PE enabled. If you build enrichment into your VE table it goes away.

[BigDaddyCool]

Tried that. Tech 2 has nothing on fuel pump..... no misfire, cylinder balance test ...... all seem the same. So I don't think it's mechanical and really I think the pump and injectors are OK.

Today: Going to try. Different Tunes.

1. Increasing Idle, Increasing Transient Manifold Volume 15%.
2. Massive timing change. Pulling 6 degree's out in the WOT area's.
3. Corvette EVAP tables with the rest of my stock transient tables.

If those three fail, I will try the EQ test to verify it's fine without PE with the OL.

[07GTS]

"fast torque exit" is using fuel cut and spark cut and powerhop is also, try to disable anything that uses fuel cut to see if its affecting it and thats torque triggered encase ur going thru some thresholds causing it, your not logging IPW so cant see if its cutting fuel at your issue point where the NB show lean spike

[BigDaddyCool]

"fast torque exit" is using fuel cut and spark cut and powerhop is also, try to disable anything that uses fuel cut to see if its affecting it and thats torque triggered encase ur going thru some thresholds causing it, your not logging IPW so cant see if its cutting fuel at your issue point where the NB show lean spike

Not it.

Alright so what everyone knows it EVERYTHING LOOKS NORMAL according to the scanner. My gut feeling tells me it's to do with transients.......... despite playing with them......... it's still to do with transient which really there's no logging for.

I'm going to presume that HP Tuners descriptions may not be accurate. Either it's repeating when it shouldn't be mid wot...... or it's something to do with them.

Another idea I had was........ the wideband transport delay as we known cannot track a PE change very well..... eg closed loop to 12.5 instantly. I'm wondering if the EVAP being set to 2.0 is simply how fast it pulls the transient at the end......... maybe on the E38's once modded they cant meet the decay requirements, so they run full transient and then just pull the fuel at a 2.0 rate at the end? .......

So I will try setting the evap to 0.1 to see if it tapers down at the 2.1 mark as well...... Scary thought if i'm correct but would be a simple fix.