atihun

Any input would be appreciated!

Symptom:

For about 2-3 minutes after cold start the idle AFR will go lean and idle drops and may stall.

Car starts up normally when cold; idles around 1100 at 12-13 AFR.
If it stalls it starts right back up easily with one crank.
If I keep the idle around 1300 it won't die.
Fuel pressure is constant, idles at 32 psi., battery voltage is at 13.


Setup:
GT35R - Large Streetport
750/1680 injectors
ISC removed
Injector Diffusers in place
BNR32 Fuel Pump
Idle - IGL 11, IGT 8 (below 60 retard set from 15 to 5) and fuel cells are set similar around the idle area.

After a few minutes of idling it's fine, which might point to a water temp fuel correction setting or the fuel isn't atomizing well enough when cold.

I've reduced the fuel correction to allow for leaner overall map when cold as it was way too rich (10's - 11's in light throttle), then I increased the idle cells a bit to get the 12-13 AFR.

I'm not sure about the Cranking (ms), but isn't this just for initial addition of fuel when cranking, or does it have any effect on idle?

Am I missing something?

cewrx7r1

iTrader: (2)

You can cure this with the commander under SETTINGS Water Temp Correction.
You have my notes, did you read page 11.

atihun

I did, and I posted that in the info above. I adjusted it so it would be at a tolerable AFR, but what's wierd is that it's in the same fuel map cell and it starts going lean (or maybe too rich) according to the WB sensor which dips to 14-18 and the car almost dies.

Should I look at raising the base fuel pressure a little? I think at 0 psi I set it to 38.

cewrx7r1

iTrader: (2)

As your ISC is removed and you are running a single manual idle which means your three ISC values are at 0, the table to reduce timing when the engine is cold will also be non funtional.
*******************************************
Do not tune idle by AFR.
After the engine is fully warmed up, adjust timing, fuel, and air flow for the most efficient combination for your chosen idle rpm.
If you want a 1100rpm idle, first increase air flow to get there. Then you adjust timing and fuel for maximum smooth idle. So now its very smooth but idling at 1300, reduce air flow and readjust timing and fuel again. You do this until you hit your target rpm with maximun timing and minimun fuel but the idle is still smooth.
Some times that timing might be 2-4 degrees below max rpm but is smoother with less or no hichups.

Did you also run the same timing and fuel in the cells around your idle cell?

Then when the car is cold the next morning, you start and only use the water temp correction table to get a good cold idle.

If you removed the hot wax rod/fast idle cam, it will be harder to get it really smooth as your revs will be lower. That is why I kept mine but put a valve in it that I can close off for summer.

atihun

Thanks.

Yes, all of the cells around the idle cell are the same. Same with ignition.

Looks like I have two things to review again.

1. Redo the idle a bit better, as before I was using the AFR as a guide. I'll try to smooth it out more when warmed up. I think that I have quite a bit of overlap with the porting that I did, so idle isn't as smooth as it could be; it sounds like a bridgeport.

2. I didn't remove the hot wax rod/fast idle cam, but I don't think it is working as when I move it by hand the idle doesn't change.