Stroked LS2 SDOL tune T56 car E40 pcm - bog on hard shift at redline log attached

[dankmac]

I've had a pretty hefty run of bad luck as well as bad weather since I started working on this, but I got some drag radials and I'm back to tuning. Test and tune day coming up a week from Sunday so I'd like to get it working better.

I found that by trying to reduce the amount of fuel being dumped during decel I took WAYYY too much VE out of it at super high vacuum high rpm. I think that it was part of my lean bog.

I have thoroughly increased both the VE and the Transient fuel at high vacuum. When lifting off the gas it pretty immediately goes rich.

The bog has improved, but is still there. The log file shows lean spikes.huge ve changes.hptstill bogs.hpl

[dankmac]

Anyone seen lean bogs on shifts like this before? Car runs perfect everywhere else (well, is as good as my tune is) and is repeatable. This would be the only "bug" I'd say.

Is there an OLSD guide somewhere for when you want to keep the car in OLSD full time?

[schpenxel]

Transient fueling issue would be my best guess without looking at logs or tune

Nothing really different about OLSD, it's the same as tuning anything else with a wideband IMO.. AFR or EQ ratio error, fix MAF and/or VE tables, etc.

[GHuggins]

Unless you can point out what to look at exactly in the log - I don't see a lean issue during shifts - I see a timing issue - I also see lots of problems with the timing maps In the tune... Basically your timing is dropping then re-ramping back up during the pull... If your able to run that much timing under full load - you should be able to run that much or more in lower load areas...

[dankmac]

There are 3-4 wot pulls in the log to look at there. After the shift it is spiking to 18:1. If you correct for delay at the sensor it is pretty much right at the shift. Other logs I have seen the injectors be significantly delayed going back to full flow rate on shifts. I thought I had fixed it by adding to the VE table at high vacuum and high rpm, but I still have the bog at shift.

Can you expand on the timing issue? One of the things on my todo list is to add more timing at part load. I was going to copy over an ls3 tune in part throttle areas. I currently am running a stock ls2 timing map except for higher VE areas.

My WOT timing was set on a dyno and made the most power with this timing curve. I'm chasing a rapidly declining VE above 6k so I think my engine just likes a lot of timing in the higher ranges. I've not heard or seen it knock sensor activity.

Interesting thought about the timing. If it drops too low maybe there's a hesitation going back to WOT causing a misfire?

For what it's worth the same timing map worked just fine with a MAF tune.

[Higgs Boson]

Sorry for posting without looking at the tune but do you have CFCO enabled?

[dankmac]

You know I never bothered to tune it out because my clutch switch isn't wired to the computer as factory. DFCO and CFCO are not functional in my car. I will tune it out to eliminate that variable.

[dankmac]

Confirmed not to be cfco causing it. It really hurts on the 1-2 shift.

[GHuggins]

There is a possibility of this causing a problem in instances like this... You have the 105kpa and up VE table all 0's... Copy the last row of the regular VE table and paste into each end of the boost VE table and interpolate between... When you floor it back out - there is a possibility of it creating pressure in the intake or at the least hitting 105ish kpa - it may be going to this table... Unlikely, but something else to try if the transient changes didn't effect it...

[dankmac]

That is exactly what it feels like and looks like is happening...hitting a complete hole in the VE table. I'm hoping to test it out tonight.

Thanks!

[dankmac]

I was really optimistic about that one. It did not improve it


boost ve table populated still bogs.hpl

[GHuggins]

OK, it's a lean throttle transition or transient fueling problem for sure... Multiply your impact and evap gas tables at 100kpa by another 1.4 and interpolate from 50 kpa to 100 kpa... After doing this go to your power enrichment tab - PE delay - 1000rpms / PE Enable - 60kpa / Enable Rpm - 300 / RPM Hyst - 30 / Pedal to activate PE - from 3500 rpms to idle rpms - subtract 10...

Those should take care of it once and for all, but if it doesn't - the last thing you can do is 0 out your prediction coefficients - all of them and then 0 out the burst knock settings to correspond... The above should take care of it though...

[10_SS]

whats your fuel pressure doing?

You may want to remove a few things from the channels list to speed up data logging.. like LTFT STFT, Ambient Air, Delivered Engine Torque, Calc Engine load, Fuel Level, some of the extra Throttle channels, Manifold Vacuum.. one of the AFR Commanded.. just to try and speed logging up, it seems pretty slow, making it harder to understand what's happening.

I have lean tip in but only over exactly 4000rpm, below 4000rpm I get nice rich tip in.. and you can see it in the injector pulse also.. something changes above 4000rpm but this is on an E38, not sure if this happens on a E40.

[dankmac]

OK, it's a lean throttle transition or transient fueling problem for sure... Multiply your impact and evap gas tables at 100kpa by another 1.4 and interpolate from 50 kpa to 100 kpa... After doing this go to your power enrichment tab - PE delay - 1000rpms / PE Enable - 60kpa / Enable Rpm - 300 / RPM Hyst - 30 / Pedal to activate PE - from 3500 rpms to idle rpms - subtract 10...

Those should take care of it once and for all, but if it doesn't - the last thing you can do is 0 out your prediction coefficients - all of them and then 0 out the burst knock settings to correspond... The above should take care of it though...

Very cool. Thanks for the advice. I'll give it a shot Thursday night. I almost asked about prediction coefficients on my post last night. I've considered zeroing them but couldn't confirm if that meant going to all 1's or truly 0. Got spooked so I left it alone.

If the lean bog is on the shift it is coming from peak vacuum then back to WOT. If I am only really adjusting the upper half of the MAP range for the transient table is that really helping the initial stab of the throttle?

[GHuggins]

Very cool. Thanks for the advice. I'll give it a shot Thursday night. I almost asked about prediction coefficients on my post last night. I've considered zeroing them but couldn't confirm if that meant going to all 1's or truly 0. Got spooked so I left it alone.

If the lean bog is on the shift it is coming from peak vacuum then back to WOT. If I am only really adjusting the upper half of the MAP range for the transient table is that really helping the initial stab of the throttle?

Yes and yes, but I think the PE settings will help as much as anything else...

[dankmac]

Still bogs. The log file shows things in a bit more detail after I erased all the irrelevant channels. Thanks for the suggestion.

You can see the bog clearly now both in RPM and in Dyn Air. It was a little bog from 2-3 and a normal pretty big hiccup on the 1-2 on the second pull.

I'm wearing out my new mickey thompons just doing these stupid tuning pulls in first hahaha

Tune attached too because I haven't shared it for a while.

bogged again.hpltransient and prediction changes FIX THE BOG.hpt

[GHuggins]

That's not as bad as it was - Leanest I could see was 16 in the log where it was going into the high 18's before...

Put the injection timing back to stock and see how it does - looks like your retarding it a whole lot way too fast...

What's the engine setup?

[dankmac]

I do feel it was a little better, but still bogged pretty hard in first. Second gear to third was more mild, but the higher gears have always been more mellow. With more aggressive shifts (holding throttle open a bit) and not doing first gear pulls I thought I had fixed it already. Putting the sticky tires on brought it back to the forefront.

I'll throw stock ls3 injector timing back into it and if that doesn't change anything I will add more transient fuel in the mid KPA range as this was the first time I adjusted below 80 KPA and it did appear to be a directionally correct change.

I had non-factory injector timing that did not retard so heavily at higher RPM and the bog was the same. These values are mimicking the curve from the spreadsheet in the injector timing thread, but adjusted for my cam timing. It is a recent change. I will say that I think my airflow increased slightly with the retarded injector timing and I also saw the AFR lean out slightly in PE - but I don't have much data with it being so cold outside.

It is a 11.1:1 compression 40 LS2 with stock LS3 heads and intake - Comp 226/242 on 117 degreed at +3.5 installed (supposed to be ground +5) on LSG lobes. Hooker exhaust manifolds to dual 2.5" with Kooks green cats. Made about 470/450 whp/wtq. I'm running OLSD because the intake is very not MAF friendly in the RX7. 4 inch tube with the MAF in a crappy double radius bend with the throttle body directly behind it. Runs good for what it is in such a light car...ran 11.40@130 on a soft launch with road race oriented suspension and tires. I'll re-cam it and put heads on it eventually. I have a set of 1 7/8 headers waiting to go on which should be a good bit of fun now that I have traction.

[10_SS]

I'm wondering if it's just a classic case of MAP is slow to respond... that's why I went back to MAF. Do you have Throttle OPening Rate table? YOu may want to reduce it to 8 or 10 from 100 just to see what happens.. you never know, it may run perfect.

Just noticed your table for this is setup a bit different.. mine is based on RPM. Yours is based on Pedal (rpm) whatever that means.. on a scale from 1.2-83.6

[10_SS]

You know, every time I think MAP Delay, I think about the COPO Whippled GM car on display at Woodward cruise.. it had TWO old school 1990 type MAP sensors connected to it.. like the ones found on a 1990 Sunbird Turbo.. not one small compact MAP.. I really think the old large sensors respond faster.. why else would GM use them on a 2011 COPO Whipple? I have pics somewhere..

Now I have this strange urge to compare old vs new MAP response time.. and the MAP channel input itself.. great

I happen to find pics.. you know the parts bin is full of small 2010+ sensors.. not so much 1990 sensors..

Why it's rotated I have no idea.
Large MAP.jpg

LEFT side old school MAP
Large Map Left.PNG

Right side old school MAP
Large Map RIGHT.PNG