adjusting cold start air/fuel

[camcojb]

My air fuel on a cold start is lean, in the 16-17:1 range. Once it goes to closed loop it pulls it back. My VE table (there's only one) is perfect once it's warmed up.

Is the table I'm looking to adjust the "open loop eq ratio P/N"? And if so, (mine is set to all "10"'s), do I raise the number to richen it? If not, what table do I want?

I did search but didn't find an answer for my 05 LS2.

Jody

[camcojb]

anyone have an idea? I don't see any afterstart fuel tables, or even an a/f modifier for cold operation with this LS2.

Jody

[EC_Tune]

AIR injection.

[camcojb]

AIR injection.

Lost me. This is an 05 GTO and doesn't have any air injection. The lean condition actually causes it to misfire a bit until the O2's correct.

The trims are always + when warming up, maybe 15% or more. But they're about 1-3% minus when up to temp so I leave the maf alone.

Jody

[EC_Tune]

Air tubes to the manifolds? (Emissions hardware, only runs for 30 sec -minute then turns off)

If you're TT then the AIR tubes may be gone anyway. The test is probably still enabled though. Check DTC P0410/411/412 or something like that.

Haven't needed to work on OLAFR too much yet. It's usually so close that it works fine.

[camcojb]

Air tubes to the manifolds? (Emissions hardware, only runs for 30 sec -minute then turns off)

If you're TT then the AIR tubes may be gone anyway. The test is probably still enabled though. Check DTC P0410/411/412 or something like that.

Haven't needed to work on OLAFR too much yet. It's usually so close that it works fine.

I'll look at those DTC's but there was no air line to the stock manifolds either. This thing does not have an air pump. Putting extra air wouldn't affect the engine running, and this thing is really lean, misfires a bit until the O2's correct.

Just checked the stock tune, those DTC's are correct but not enabled so there definitely isn't an air pump on the LS2's in this car.

So there's no way to richen the tune at cold open loop? Thanks a lot for the ideas!

Jody

[EC_Tune]

Thought that may be the case but wasn't sure.

Lets test something & see how it works:

Take your IVT Gain table & Mult x2
Start & idle it. See what the AFR's do until closed loop is enabled.
Rinse & repeat.

At some point your afr's should be pretty close on startup. Need some scanner support for this to really work well. Not sure if these values are available in the data stream though.

Chris???

EC

[camcojb]

Thought that may be the case but wasn't sure.

Lets test something & see how it works:

Take your IVT Gain table & Mult x2
Start & idle it. See what the AFR's do until closed loop is enabled.
Rinse & repeat.

At some point your afr's should be pretty close on startup. Need some scanner support for this to really work well. Not sure if these values are available in the data stream though.

Chris???

EC

Thanks a lot. I made the change and will see how it does in the a.m.

Jody

[WS6FirebirdTA00]

SD tune? If so welcome to the hell of SD tuning. There are start up bugs making the car lean in SD tuning. At least that is how it is on the older cars.

[camcojb]

SD tune? If so welcome to the hell of SD tuning. There are start up bugs making the car lean in SD tuning. At least that is how it is on the older cars.

No, this is a normal blow through maf tune. I tried doubling those numbers and it was way rich. So I put the stock numbers back in and then raised them by 25% to start with. Much closer. I'll keep fine-tuning from here and see if I can get rid of it.

Thanks again guys.

Jody

[EC_Tune]

Cool! Sound like you're on the right track.
Post up anything else you find.

EC

[WS6FirebirdTA00]

ok got ya

[camcojb]

Cool! Sound like you're on the right track.
Post up anything else you find.

EC

I ended up at 12% higher than stock numbers for that table; that got me from 17-19:1 misfiring on cold starts to low to mid 13's a/f on a cold or re-start. Then in a few seconds it leans to 14.7, all the time smooth as silk.

Thanks again for the help.

Jody

[WS6FirebirdTA00]

so what exactly did you change again?

[camcojb]

so what exactly did you change again?

I adjusted the IVT gain table. Changed the entire table + 12% which richened my cold and re-start a/f by 3-4 points. Small changes do big results with this one.

Jody

[WS6FirebirdTA00]

where is this at? is it just an ls2 deal?

[camcojb]

where is this at? is it just an ls2 deal?

Could very well be. It's at engine>fuel control>open and closed loop>open loop. Called IVT gain.

Jody

[EC_Tune]

Yes it's LS2 only. New PCM new stuff inside.

I just want to know how GM figures out the Intake Valve Temperature & why the H.E.double hockey sticks they made open loop so complicated...

EC

[MNR-0]

The equivalent for LS1s exists in:

Engine|Fuel COntrol|General|Initial Adder vs. ECT

There is an adder for IAT but it is zeroed out from factory (at least on my PCM).

If you want to add fuel on start-up then increase these values and vice versa.