Lean transition into PE and lean spot during WOT

[Higgs Boson]

I think we are not fully understanding each other or maybe its just me. But if you want to use closed loop/O2 sensors AT ALL, then you CANNOT use these tables for PE. Even when the ECM exits closed loop for PE these tables no longer have an impact. Only in full open loop mode, O2s disabled do these function. Something in the ECM logic dictates that these tables are not used in a closed loop system even in once in PE.

That's what you read or that's what you tested and experienced?

[brentsten]

I think we are not fully understanding each other or maybe its just me. But if you want to use closed loop/O2 sensors AT ALL, then you CANNOT use these tables for PE. Even when the ECM exits closed loop for PE these tables no longer have an impact. Only in full open loop mode, O2s disabled do these function. Something in the ECM logic dictates that these tables are not used in a closed loop system even in once in PE.

Actually, they are used but only if the OL tables command a richer EQ than the PE tables. Same theory applies to Boost Enrichment with the enhanced OS; richest table gets used.
I setup a closed loop tune, flat lined the PE table to 1.0 and used the Airflow Gain table to command 1.28 EQ. I eventually achieved my target AFR, BUT I still have the 2 second delayed lean spike doing it this way. I've narrowed the cause down to the closed loop to open loop transition (usually by PE activation).

I've been running a full open loop tune for months and commanding enrichment through the Airflow Gain table > 100kPa. It's the only way I've found to get rid of the spike entirely. Part of me wishes I had o2 feedback, but with a nicely dialed in MAF and/or VE table, mileage doesn't really suffer. Plus, you can tune for lean cruise

[Niemer]

I've been running OL for a while and the spike still shows up when PE is enabled. I'm going to try building PE into the VE table and disabling the built in enrichment to see if I get the same results.

And I've actually been getting better mileage that when I was running CL.

[alexl226]

I'm in the same boat guys...sub'd.

[schpenxel]

Actually, they are used but only if the OL tables command a richer EQ than the PE tables. Same theory applies to Boost Enrichment with the enhanced OS; richest table gets used.
I setup a closed loop tune, flat lined the PE table to 1.0 and used the Airflow Gain table to command 1.28 EQ. I eventually achieved my target AFR, BUT I still have the 2 second delayed lean spike doing it this way. I've narrowed the cause down to the closed loop to open loop transition (usually by PE activation).

I've been running a full open loop tune for months and commanding enrichment through the Airflow Gain table > 100kPa. It's the only way I've found to get rid of the spike entirely. Part of me wishes I had o2 feedback, but with a nicely dialed in MAF and/or VE table, mileage doesn't really suffer. Plus, you can tune for lean cruise

I've noticed something weird now that the morning temperatures have dropped here

On a cold start I'll usually see commanded lambda of 0.98 or so at idle. But, if I start driving pretty quick after startup it will go down lower than that.. I think I saw it commanded 0.88 lambda this morning

The weird thing.. my wideband was still right at lambda=1 and was oscillating slightly higher/lower like the O2's were cycling, i.e. it was behaving like it was in closed loop.

That seems strange to me that it would command < 1, but still be in closed loop and staying around 1. I'll try to get a log tomorrow

[Niemer]

Funny you mention that, I'm getting some wicked cold start issues right now, massive idle surging for about 30 seconds then it'll settle down. It's so bad I can't shift into reverse without it stalling out. Only started happening with temps ~50F, all summer it was fine.

[GHuggins]

Funny you mention that, I'm getting some wicked cold start issues right now, massive idle surging for about 30 seconds then it'll settle down. It's so bad I can't shift into reverse without it stalling out. Only started happening with temps ~50F, all summer it was fine.

What's air fuel when it's doing this? You may need to add about 5% in the open loop colder areas...

[alexl226]

does your rpms drop when the lean spike happens? Mines does. appears to be happen at lockup for me? I never had this issue prior to the 4l80e swap I just finished btw. Do you guys also have the ISS disabled?

[realcanuk]

I've noticed something weird now that the morning temperatures have dropped here

On a cold start I'll usually see commanded lambda of 0.98 or so at idle. But, if I start driving pretty quick after startup it will go down lower than that.. I think I saw it commanded 0.88 lambda this morning

The weird thing.. my wideband was still right at lambda=1 and was oscillating slightly higher/lower like the O2's were cycling, i.e. it was behaving like it was in closed loop.

That seems strange to me that it would command < 1, but still be in closed loop and staying around 1. I'll try to get a log tomorrow

What I have noticed, and Chris @ HPT confirms, is that the STFT start working almost immediately in and create a semi closed loop state. Emissions related I read. The ECTvs StartupECT actually controls the LTFT although even though it is under "closed loop enable". I have been meaning to try increasing the "delay" seconds because I read somewhere that this might delay everything. For example if putting 300 seconds would delay the STFT for 5 minutes, that could help that issue.
I always forget to play with it because on my car, although the STFT start almost right away, and try to lean it out to stoich, it isn't that bad. I feel it for a minute or 2, but it doesn't stall or anything like that.

Quote from Chris........ "the STFT's will function in a kind of pseudo closed loop state, designed to assist emmisions on cold start, full closed loop happens after the closed loop ECT and delay are met. "

[Niemer]

What's air fuel when it's doing this? You may need to add about 5% in the open loop colder areas...

It's oscillating from lean to rich or visa versa. Odd thing is, actual EQ is never reaching commanded EQ during warm up, it's always leaner, 0.9 lambda actual when 0.8 lambda is commanded.

[Niemer]

does your rpms drop when the lean spike happens? Mines does. appears to be happen at lockup for me? I never had this issue prior to the 4l80e swap I just finished btw. Do you guys also have the ISS disabled?

No rpm drop when this happens for me, I'm also not locking up at WOT.

[Niemer]

What I have noticed, and Chris @ HPT confirms, is that the STFT start working almost immediately in and create a semi closed loop state. Emissions related I read. The ECTvs StartupECT actually controls the LTFT although even though it is under "closed loop enable". I have been meaning to try increasing the "delay" seconds because I read somewhere that this might delay everything. For example if putting 300 seconds would delay the STFT for 5 minutes, that could help that issue.
I always forget to play with it because on my car, although the STFT start almost right away, and try to lean it out to stoich, it isn't that bad. I feel it for a minute or 2, but it doesn't stall or anything like that.

Quote from Chris........ "the STFT's will function in a kind of pseudo closed loop state, designed to assist emmisions on cold start, full closed loop happens after the closed loop ECT and delay are met. "

I think I saw this exact thing happen this morning, I was watching actual vs commanded and noticed that the closed loop status bit turned on within a minute of start up, sooner than it should have based on the ECT table. I'll try messing with the delay as well as the O2 readiness checks.

[realcanuk]

I think I saw this exact thing happen this morning, I was watching actual vs commanded and noticed that the closed loop status bit turned on within a minute of start up, sooner than it should have based on the ECT table. I'll try messing with the delay as well as the O2 readiness checks.

Yup... it turns on the status bit too.... it doesn't seem to tell the difference from full closed loop or that..

[alexl226]

I went back to my VE only tune. Much less pronouced but still there, sometimes. Didn't seem to be consistent on time either(always around 2.xx seconds though). Working on disabling PE all together and building it into the VE...

Update:
failing at tuning boost into ve....gunna need to read up some...

and I also have same wild swing when cold out on startup. Also have ID injectors but have ID725's.

Really find this odd that I never had this issue in the past.....this suburban was dialed in prior to the transmission swap.

I just looked at a bunch of old logs and find no evidence of lean spike. I think I would also have remembered this.

Really frustrating..

[alexl226]

Files Attached Below:

leanPE_2.hpl

07 Stock Suburban2_Backtostock2_pe2_maf2_boostPE1_spark3_4l80e2_1_99peramp_12afr_velow1_fuelmass.hpt

~Burban Setup~~LAMBDA1~Trans1.cfg

Attached is a log + config and my current tune. I'll gladly paypal anyone who is willing to spend their time to figure this out.

You can see the spikes are inconsistent. Happen at different times, sometimes are almost not apparent at all...If I'm quick into boost it seems to take seconds to react and finally fall into line.

How exactly are you tuning the gain tables? I assume force MAF to fail, tune like you would tune VE and just change your airflow gain table like you would the BE table?

[schpenxel]

Add ignition voltage, air cal mode, dynamic airflow, VE airflow, fuel trim cell and injector flow rate

You can remove some of the TCC stuff if you need more room to add PID's

[10_SS]

I think it's sad that I can tell if a TVS or Whipple is installed based on the sudden MAP increase from 95-115kpa, and no change in TPS or RPM (showing just that the bypass valve is closing), which on my car makes me get all sideways and feels like a 35hp nitrous shot... just not cool.

BTW, for anybody that messed with transitional fueling.. if you've ever touched it.. then that could be the reason your seeing some weird change in PE fueling 1-2 seconds out. I had an instance where I had a flat AFR curve, then made some changes to the Transients, then 1-2 sec out I had some rich spike consistently.. which made me try to tune it out in MAF and VE... well then I did that and just made the spike go lean right after the rich spike.. instead of just rich. I went back to the file right before messing around with transients, and BAM.. no more spike. And I never really fixed my lean tip in by using transients anyway... so I say hell with messing with transients. The only thing they ever did for me was fix a lean COLD non-PE tip in issue (copying ZL1 open loop, cold settings).

BTW your reported injector pulse is dead steady through the WOT PE lean spot... so I would say check fuel pressure or connect a Soundcard scope to an injector wire to see if the pulse is actually changing, and add something like IVT or fuel pressure... those are known to affect final fueling.

[schpenxel]

I noticed the same.. Injector PW is basically damn near level through the entire area you're in PE.. so that makes me really wonder why it's going lean like that.

Any chance it's a misfire or something like that causing a false lean reading?

Fuel pressure would be a good one to log too.

Injector PW on gen 4's is reported as the BASE pulsewidth only, prior to any adders. I suppose it's possible you could be hitting a weird spot in the fuel injector offset table due to a voltage drop or spike or something... that's why I mentioned logging voltage

Beyond that I've got nothin'

[alexl226]

Add ignition voltage, air cal mode, dynamic airflow, VE airflow, fuel trim cell and injector flow rate

You can remove some of the TCC stuff if you need more room to add PID's

Just finished adding these. Will log some tonight.

May start working on the airflow gain tables though. Seems like the OP has tried just about everything.....

I think it's sad that I can tell if a TVS or Whipple is installed based on the sudden MAP increase from 95-115kpa, and no change in TPS or RPM (showing just that the bypass valve is closing), which on my car makes me get all sideways and feels like a 35hp nitrous shot... just not cool.

BTW, for anybody that messed with transitional fueling.. if you've ever touched it.. then that could be the reason your seeing some weird change in PE fueling 1-2 seconds out. I had an instance where I had a flat AFR curve, then made some changes to the Transients, then 1-2 sec out I had some rich spike consistently.. which made me try to tune it out in MAF and VE... well then I did that and just made the spike go lean right after the rich spike.. instead of just rich. I went back to the file right before messing around with transients, and BAM.. no more spike. And I never really fixed my lean tip in by using transients anyway... so I say hell with messing with transients. The only thing they ever did for me was fix a lean COLD non-PE tip in issue (copying ZL1 open loop, cold settings).

BTW your reported injector pulse is dead steady through the WOT PE lean spot... so I would say check fuel pressure or connect a Soundcard scope to an injector wire to see if the pulse is actually changing, and add something like IVT or fuel pressure... those are known to affect final fueling.

Yes it is dead even....maybe a base pulsewidth?

[alexl226]

I noticed the same.. Injector PW is basically damn near level through the entire area you're in PE.. so that makes me really wonder why it's going lean like that.

Any chance it's a misfire or something like that causing a false lean reading?

Fuel pressure would be a good one to log too.

Injector PW on gen 4's is reported as the BASE pulsewidth only, prior to any adders. I suppose it's possible you could be hitting a weird spot in the fuel injector offset table due to a voltage drop or spike or something... that's why I mentioned logging voltage

Beyond that I've got nothin'

Beat me to it. Looks like it is a base pulsewidth...

Also, no I do not believe it is misfire.