Lean transition into PE and lean spot during WOT

[07GTS]

wouldn't have anything to do with the "fuel from wall stabilisation" been set on 1 or 2 ive herd the lsa injectors are set to 1 because of the spray patten points into the valve where other injectors set to 2 just spray like normal, i have changed that number and it does make a difference with fueling changes but not sure if it would help with this or not

[BigDaddyCool]

I only see this on my G8 with boost with different injectors then LSA/LS9. Friends G8 with same cam I have doesn't have any issues with this, but another friend's G8 with a different cam is fine. Difference between the two blown cars is the injectors, friend's is running the stock LSA/LS9 injectors while i'm running the Deatchwerks 95 lb injectors. I've changed all the transient fueling and it doesn't seem to have an effect one or another.

While thinking of this my friend's V with the same injectors I have had a similar issue that only happened at the drag strip we chalked up to possible fuel delivery. He would launch the car and shortly after the 60' mark it would go lean then pick up right away just like mine does. I don't think it is anything with the injectors as much as maybe a table that isn't changed to accompany the extra fuel flow possibly, possibly hard cap somewhere in the background? My friend's V we were able to apply the fuel flow rate without needing to do the half/double Flow/AFR trick like on my G so i tend to think it isn't anything with that. He just upgraded to a ZR1 with the same injectors and we put in the data, haven't done any logging yet but will def watch no the dyno and street to see if it catches the same thing.

Mine only does it while in PE. I tried a few things, i didn't even realise that PE isn't actually open loop either....... thinking I could mix something together nup.

If set the car up in open loop and ensure it cant enter PE and just use the open loop airgain table to set the AFR eg. 90-100kpa map........ stand still launch no lean spike...... It's a damn bug in PE ... It's crazy because you cant slowly enrich fuel in open loop doing it the other way and you waste alot more fuel.......

Chris from HP Tuners needs to chime in and check this out I recon. We really need to find why this is dropping out of PE without reporting it.

The only other question I have is........... do the cars that have this issue have a different map sensor? Not stock, as in has been replaced. I noticed in the software it has an estimated map area now.... perhaps while it seems to be working fine there's something a miss there. I have my old one and I think i'll refit it and try again.

[BigDaddyCool]

I'm kinda of the opinion on this PE lean issue it's probably not a OS bug.......

Before I went from my stock L76 cam to the LS9 cam, it breathed alot better down low and never had a PE issue...... now with the LS9 cam with my PE issue I can get rid of different ways, but it's not a guarantee it wont happen. At this point I think that possibly whats happening is that the manifold builds pressure and cant get the air out..... (where on the stock cam it would)..... and it either blows air backwards through the maf (stops reading increased air) or it blows a hose causing a vacuum leak for a split second. Sure it doesn't explain why PE fuelling seems to only go back to stoich and that it doesn't report as dropping out of PE but still..... perhaps the car picks up on this and drops back to closed loop. Another theory is it's purely transient fueling .... a timing thing.. how fast you get it to kick in, how fast is tapers off etc but I think it's a band aid fix if it is this.

I know my gearbox can change gears in manual mode sometimes automatically and not report it (dont know why).....

After fixing up my intake stuff my VE increased ..... meaning it helped fixed something. And after doing various MAFLESS vs MAF vs MIXED Mode runs...... I've determined it's mostly in MAF where the issue lies. Mixed mode halves the issue and MAFLESS virtually doesn't have it or it's less then half at worse....... usually never happens in mafless.

I am thinking that the 3 hoses on the intake manifold are where I need to look. They come with these shitty stock GM connectors.... and I dont trust they are sealing plus there's two right after the throttle/maf so VAC LEAK CENTRAL if you ask me, the other thought I had was my DOD system.. I changed the valve cover etc which has the PVC on it and capped the stock DOD one/rocker cover. Perhaps on these engines that rocker cover PVC valve is meant to releave pressure and thus prevent this? ..... I'm thinking of capping the new one and hooking back up the old one.

Like the L76 stock cam used to run 60-70g/sec under 3500rpm from idle airflow wise. With the LS9 it does 48-56g/sec. So it's definitely more constipated. The problem I have with that is it screws up closed loop, all the various area's as under 4000rpm doesn't even reach the highest closed loop point of 64/g sec. But above 4000 hits near 80g/sec. The spark table, the closed loop prop tables, they are all out...... and cant be compensated for.

The LS9 cam is a **** cam for NA for that reason.

But the PE thing....... perhaps we could collectively put our changes on the table and see what we have in common?..... (Sorry for the rant).... just trying to put information on the table.

[griffincox]

You are correct it will use whatever is richest between the 2, but for some reason as soon as you turn CL back on. It ignores the Open Loop Map enrichment table. I kinda use a similar technique on the LS1b platform using efilive's cos. I set the map enrichment table upto 105kpa then use pe enrichment at a designated higher map at say 125/130.

E38/E67 just wont play ball with CL on.

All cars i tune are Speed density only, none have a maf fitted.

Can you clarify? If you have closed loop enabled, and open loop is triggered by PE (is there any other reliable way to trigger open loop?) will the OS fuel with the greater of the two EQ ratios or will it fuel with EQ ratio in the PE table? I am referring to the EQ ratio derived from [ECM] 12435, [ECM] 12441, [ECM] 12440 tables.

[BigDaddyCool]

May I just ask, is there anything wrong with:

Connecting my rocker cover pvc outlet with the valley cover outlet to the intake infront of the maf. Before the cam change I didn't have this extra valley cover one. I originally blocked the rocker cover one and piped the valley cover to my intake.

Somethings not right....... today I connected them together via a T peice, with the flow working for the rocker cover pvc (t peice) and the valley as a into stream part of the T peice.
...........

I dont know how they work. The rocker cover surely blows oil/fuel out to the intake? to be recycled? ........ and the valley cover does the same just to get rid of bad gases right? ...... having them connected together I presume would contaminate the oil now I think of it......

Thoughts.

: Attached picture, ignore the 'oily air out' not my photo.. just got the light blue and the T as a diagram of how it's setup. Runs infront of my MAF / OTR intake.

[07GTS]

rocker cover is ment to breath and crank is ment to have vacuum, i have left my rocker cover to vent and added the passenger rocker cover to vent also and put the crank vent thru a catch and to the intake before the TB, i was doing some tests a while back and have a log saved somewhere and was amazed at the change in AFR just from having the crank venting compared to vacuum behind TB, i have read that the extra fuel from a cold start can get into the oil and then the fumes can get used back thru the breather durin warm up which could explain why i went lean durin first part of warm up after the change in my venting compared to vacuum but once oil is at 100 deg and engine at operating temp it should be normal again

[Tre-Cool]

Can you clarify? If you have closed loop enabled, and open loop is triggered by PE (is there any other reliable way to trigger open loop?) will the OS fuel with the greater of the two EQ ratios or will it fuel with EQ ratio in the PE table? I am referring to the EQ ratio derived from [ECM] 12435, [ECM] 12441, [ECM] 12440 tables.

In my experience, only the ls1b controllers run the richest of the mixtures. the later model seems to ignore the open loop map tables all together when you use closed loop.

[GHuggins]

May I just ask, is there anything wrong with:

Connecting my rocker cover pvc outlet with the valley cover outlet to the intake infront of the maf. Before the cam change I didn't have this extra valley cover one. I originally blocked the rocker cover one and piped the valley cover to my intake.

Somethings not right....... today I connected them together via a T peice, with the flow working for the rocker cover pvc (t peice) and the valley as a into stream part of the T peice.
...........

I dont know how they work. The rocker cover surely blows oil/fuel out to the intake? to be recycled? ........ and the valley cover does the same just to get rid of bad gases right? ...... having them connected together I presume would contaminate the oil now I think of it......

Thoughts.

: Attached picture, ignore the 'oily air out' not my photo.. just got the light blue and the T as a diagram of how it's setup. Runs infront of my MAF / OTR intake.

The one coming from the valley cover needs to be plumbed in behind the TB somewhere so it pulls vacuum on the crankcase... The one coming from "that" valve cover is fresh air for the crankcase - it needs to come from the intake tube after the air filter and MAF but before the TB...

[BigDaddyCool]

Not really sure how I'm meant to plumb that the way your saying.... behind the maf there's the TB and just behind that there's a vent left and right of it. The left one goes to the rear passenger side of the engine, the right loops around to a EGR thing on the left I think... and then I don't have any space to plumb the rocker cover line to behind the behind the maf but before the TB as I only have a silicon tube there (short) ...... I have a RamJET OTR.

I could probably obviously cut the line that links the front and back and merge the valley cover into that...... for the vacuum side of it. But the rocket cover nothing really can be done there I think......

Another thought I had with the PE is the EGR...... Haven't logged that while checking this PE thing.

[BigDaddyCool]

The lean PE issue is certainly a question mark........... two things that will help it. DO NOT ZERO DYNAMIC AIRFLOW. I say this because I suspect based on my own tuning experience the car is momentarily dropping the MAP signal causing this (doesn't show up on custom os only on stock os in mafless mode with dynamic zeroed)...... and by zeroing out Dynamic there's no carry over of estimated airflow to keep the car rolling when this happens. You can notice this on the stock OS, it will cut fuel and feel bad like you've dropped a few pistons bad.... custom os..... you dont notice it just goes lean.

My final thoughts.......... Tuning Dynamic Airflow & Transient Fuelling....... is the answer to compensate.

[Niemer]

SOLVED!

Engine -> Fuel -> General. Injector Control, Enrich Desoot Mode

Set to disabled.

[rao]

Great to see a resolution.

[10_SS]

SOLVED!

Engine -> Fuel -> General. Injector Control, Enrich Desoot Mode

Set to disabled.

Is this a real thing? I dont have it. Can you take a screen shot?

[Niemer]

It's in the latest beta, sounded like Chris was going to add it to the rest of the OSs and possibly the 3.4 daily updates really soon.

[10_SS]

It's in the latest beta, sounded like Chris was going to add it to the rest of the OSs and possibly the 3.4 daily updates really soon.

wow awesome thanks for the update. I dont have the lean blip 2sec out but I do have lean transient above 4000rpm exactly... wondering if that will change.

[GHuggins]

wow awesome thanks for the update. I dont have the lean blip 2sec out but I do have lean transient above 4000rpm exactly... wondering if that will change.

When you get it - it's at the bottom of the page

[GHuggins]

Big thanks to BigDaddyCool and Chris on this...

[10_SS]

When you get it - it's at the bottom of the page

thanks! I am checking my tune along with 20 or so 2007-2010 tunes, none of mine have this I was starting to think I was looking at the wrong place. Hopefully they add it soon...

Running 3.5.632, my main OS is the 2bar updated 12637084 -> 1250235

[Tre-Cool]

It's also possible it's not enabled on all years & calibrations too.

I primarily tune with efi, so I'm getting it added in there too. It was a problem effecting both products so you guys were not alone on this problem.

[realcanuk]

It's also possible it's not enabled on all years & calibrations too.

I primarily tune with efi, so I'm getting it added in there too. It was a problem effecting both products so you guys were not alone on this problem.

HPT just informed me that it is not possible to add to my 07 E38, because the setting doesn't exist in mine. I never had a lean spike issue that I couldn't get rid of so I assume that if its not in the calibration, it doesn't have the negative effect.