Strange AFR at idle

[Cybnext]

Alright, went to the track last night with the owner to try and get fueling better. Looked like I had it mostly right. Had a few strange issues though.

1. At the beginning of the night, his idle AFR was LEAN (17-19), so I added about 20% to the idling cells for the MAF and got it to about 13's. But everytime after driving around for a bit, his idle would go even richer. The AFR error in those cells were ~-4s. Finally stopped getting richer once it hit 12.8.

2. While reviewing the logs, I noticed that when he would push in the clutch the commanded EQ would go back to 1.0 instead of 1.130 and back up to 1.130 after the shift, so the AFR was thrown off for that time. I had DFCO and CFCO turned off.

I played with the idle base spark table and the car seemed to idle better, but I'm still not really comfortable doing spark. Ordered the Learn@Home book so hopefully I get a better hold of how to tune spark.

Thats all I can think of right now.

Here is the tune and log files.

[Cybnext]

one more log

[ShoddyHog]

How are you tuning your VE and MAF tables? I used the SD Tuning guide to do both, and haven't touched either of them since then without using the AFR error % with the exception of VE. I did some hand smoothing on the VE. I can post up one of my logs, but my AFR doesn't wander hardly at all compared to yours.

I opened up your tune file, and saw a couple things. First, I understand not being comfortable with tuning timing at higher load/rpms, but you should not be afraid to set your timing at the idle ranges up like that other guy posted, and like BBA said. Your high octane table is still bone stock. I'd think you're going to have to change those idle values at the very least.

You also probably going to need to add some to your base idle airflow tables (Airflow final minimum) like the other guy's Torquer.

Also, once you're done tuning the VE and MAF, are you enabling your trims? The job of the trims is to keep the AFR at commanded, right?

Just a couple thoughts...newb tuner here.

Gerry

[Cybnext]

I tuned the VE and MAF with a WBO2 using the SD Tuning guide in the stickies. I may need to do another run over the VE table to get it closer, then do the MAF again.

I'll try playing with some of the spark, hopefully the Learn@Home stuff really helps me get a hang of this and I can knock out this tune. I feel a bit bad because the guy lives like an hour and twenty minutes away and has driven up twice already. I'll keep reading and hopefully understand what I'm doing with spark very shortly.

I've done the RAF minimum and the car seems to idle great. I'm pretty sure since its a M6, I only need to add to the neutral line, which is why the others look way off.

[ShoddyHog]

Well, if those logs were done with the tune you posted as is, I don't know if I can help. It appears as though you're in open loop doing the logs, if so and if your VE and MAF are not dialed in, then that would explain the swings. If you're in closed loop, then I'm totally lost because your O2's arent reading, and your trims are not functioning.

Gerry

[Cybnext]

Since I don't have access to this GTO, I played with my spark table on my mostly stock 2000 camaro (LTs, ory, 4.10s and lid) and what a difference it makes setting the idle areas to a static number. Before if I didn't get the right ratio of clutch and accel the car would almost die (spark would drop to 13s, I think, now it stays a solid 22), now it barely surges and starts going.

I've played with the GTOs spark table, so hopefully I can get it in the car soon and reset the VE and MAF tables and redo the fueling. Didn't realize the best way to do the LS2VE was with marcin's spreadsheet. So I'll do it with that this time.

[BBA]

Also, once you're done tuning the VE and MAF, are you enabling your trims? The job of the trims is to keep the AFR at commanded, right?

The trims are to keep the O2 sensors cycling during closed loop. If high trims are present, it means your airflow and VE tables are off and your commanded will not be right when in open loop.

[ShoddyHog]

The trims are to keep the O2 sensors cycling during closed loop. If high trims are present, it means your airflow and VE tables are off and your commanded will not be right when in open loop.

The way I understand it is if you're running open loop and your VE tables are dead on, then your AFR will be as well. Then when you go back to closed loop, your LTFT's should stay pretty close to 0.

I was just confused about what the OP was doing. Looks like all the logs were made in open loop. If that is true, then compared to my logs running OLSD today, I'd say the OP needs to start back at square one and get the VE dialed in.

Gerry

[ShoddyHog]

I've played with the GTOs spark table, so hopefully I can get it in the car soon and reset the VE and MAF tables and redo the fueling. Didn't realize the best way to do the LS2VE was with marcin's spreadsheet. So I'll do it with that this time.

I tune VE on my LS2 using a wideband using the SD Tuning guide. Not sure what you mean by tuning VE with a spreadsheet. Care to explain/share?

Thanks,
Gerry

[BBA]

The LS2 has two models of PCM's, one with a VE table and one without. The later models have coeficients that calculate VE on the fly instead of looking up a table. To adjust VE on these PCMs you have to convert the coeficients into an equivalent VE table and copy to a spreadsheet to do the corrections, then you convert the corrected table back to new coeficients and set the new values in the PCM.

It can be done using either the OL wideband method or the closed loop narrow band method. Personally I think the closed loop narrow band method is more accurate as it removed wideband calibrations from the equation, instead depending on sensor cylcing at stoichometric AFRs.

[Cybnext]

I was under the impression that marcin's spreadsheet is for any LS2, not just those with the equation.

EDIT:
http://www.hptuners.com/forum/showthread.php?t=11906

This thread has some info on what I'm talking about.

[ShoddyHog]

I haven't had time to look at this spreadsheet. I've been using the method stated above, and I seem to be able to get my AFR dialed in very well in OLSD.

At any rate, with your AFR all over the place in OLSD, you've got work to do because to me, it looks like your VE is still way off.

Gerry

[Cybnext]

I've read more into the LS2 VE spreadsheet deal, and it looks like its not needed.

I'd like to get this car tuned, but the guy lives an hour and a half away and works nights, so its difficult to find time to get everything setup.

Maybe I just need to take a day off of work and get it finished for him.

[Cybnext]

Alright, I've read a few threads and since this car isn't THAT modded, would it be alright to return the VE to stock, leave it like that and just tune the MAF?

[5_Liter_Eater]

Sure. As mentioned it hardly ever looks at the VE. If you put the dynamic airflow high RPM Disable to something like 500 RPM then you are gauranteed it will be referencing the MAF solely.

The LS2 (E40) VE table is kind of a PITA. I need to go back and read why Marcin's spreadsheet is not needed (he recently told me that as well) and lately I have been using multiply by % - 1/2 and it seems to be working OK.

[Gh0st]

Sure. As mentioned it hardly ever looks at the VE. If you put the dynamic airflow high RPM Disable to something like 500 RPM then you are gauranteed it will be referencing the MAF solely.

The LS2 (E40) VE table is kind of a PITA. I need to go back and read why Marcin's spreadsheet is not needed (he recently told me that as well) and lately I have been using multiply by % - 1/2 and it seems to be working OK.

I've actually been considering doing just that but leaving it at 1000rpm. I set mine to 500rpm the other night and the car wouldn't idle right and lord knows I hate dealing with idle issues

Doesn't seem like a bad idea to have it set to 1000rpm if you have your idle nailed down. This way you only have to worry about your MAF fueling be correct. Only issue I can see is if the MAF fails and your VE table is HORRENDOUSLY lean.