What is the "ideal" cranking AFR?

[99LS1SS]

I'm having a lot of trouble with hot starts and when I log a cranking cycle my Air Fuel Ratio Commanded Hi Rez reads a 7.08. I'm guessing that is too rich for the car to be able to start. What tables need to be adjusted and what AFR should I shoot for?

[99LS1SS]

Well, I've decided to basically put everything back to stock with the exception of the spark tables and the MAF. I'm going to try adding only startup air and see what that gets me.

[99LS1SS]

I have just changed my tune about 20 times trying various things. I tried more startup air, less startup air, more cranking fuel, a lot more cranking fuel, less cranking fuel, a lot less cranking fuel and a bunch of combinations of those two and nothing seems to help my startup issues.

[LSX378]

Have you tried Injector Temp Gain? This is mainly to assist with hot starts.

[Jamz]

I have the same issue when cold. Or after the car rest for about an hour and i switch on the ign. The commander afr is about 4-9 which is way too rich.

After i crank it and it starts then it quickly runs through 13-14.68.

Which tables / settings reference the commanded AFR on reds/ign ON with no cranking.

I have adjusted the openloop IVT base table and Gains tables. Without success.

Thankyou

[HartsG8GT]

Same issue here. If the car sits for about an hour after shutting off then it is hard to start. I would love an answer to this since I can't seem to figure it out.

[Jamz]

Yeah. The weird thing is mine runs perfectly when at full operating temp. Idles nice. No much of an idle dip in gear or park free revving. But when cold or after shut of for an hour it seems overly rich when restarting and stumbles and wants to dip and stall sometimes until full operating temp is reached. I have a 216/226 cam and LT headers and thinking it may be an open loop fueling issue. So i Played with the 50kpa settings In the ivt gain table as that's where my cam now idles but there's still an issue . I'm going to go over the ve table once more in the idle areas as I'm in full sd mode but I'm sure it's pretty close as my fuel trims are usually -2 to +2.

Any tips would be appreciated

P.s . I don't have a maf installed and in sd mode so can anyone help explain the process of working out the idle airflow without the maf in a l98 gen4? Do you use the ve airflow pid in the scanner?

[IDRIVEAG8GT]

Increase OL P/N and In Gear fueling for the corresponding IVT versus Coolant temp. Problem solved.

[Jamz]

I have modified the airflow minimum vs etc multiplier table so that's there is more minimum running airflow at colder ect temps to fix the problem.

The idle guide I read on the forum shows how to log the idle airflow on a gen 3 vs ect from a cold start right through to hot. In the gen 4. I found the hot running airflow numbers and used the multiplier table to add air for lower ect's.

Hope that helps someone else with the same problem.

[Jamz]

Increase OL P/N and In Gear fueling for the corresponding IVT versus Coolant temp. Problem solved.

The issue wasn't adding fuel, it was actually rich after I installed my cam. I actually had to reduce fuel in the ivt gain tables, drop the cranking ve to 80% across therboard and increase base running airflow for colder temps to get a nice afr for cold and warm startup / driving.

[IDRIVEAG8GT]

The issue wasn't adding fuel, it was actually rich after I installed my cam. I actually had to reduce fuel in the ivt gain tables, drop the cranking ve to 80% across therboard and increase base running airflow for colder temps to get a nice afr for cold and warm startup / driving.

Uh.... Well if that works for you that's dandy.

I've never had that much issue nailing down hot and cold starts by simply changing minor OL stuff and airflow tables but then again I guess every car is different.