Crank fueling when engine warm.
 

Hi friends. Finally getting back into tuning, been out out of it for a few years. Just been working on general tune, getting BLMs back near 128. Car seems to run good, just have this one nagging thing. I have long engine cranks when the car is warm. When cold, like sitting overnite in garage, fires right up in a snap. Now you would think this should be an easy fix, but have not nailed it down yet. Been taking fuel PW out of the crank fuel PW vs coolant table. Actually tried adding fuel 1st, to see what affect that had, and it seemed to make it worse. That is the only table i been working on for now. Was thinking of next cutting back on the multipler vs DRP table, see what that does.

Are there any other tables that affect things during crank? What about the warm IAC park steps vs coolant? Also the startup spark tables, but i think they aren't used till after the engine is declared running. There are also several IAC scalars that could affect startup?
Thanks, this always cool stuff learning about ECM control...

Re: Crank fueling when engine warm.
 

As you are doing I would first work with the cranking PW versus coolant table. And of course only change it in the area that corresponds to the engine temperature.

You are correct about the base distributor timing, it is used during cranking.

The IAC is a good place to work on. Can even try holding the go pedal down about a 1/4" while hot cranking. See if that makes a difference. If so can add to the IAC step table.

If not then maybe subtract a little from the IAC park vs coolant table.

RBob.

Re: Crank fueling when engine warm.
 

Ok Rbob, i will keep working on the crank fuel PW table. I dont want to change too many things at once, and not know what fixed my issue! Havent really thought of giving it a little throttle during long cranks, but that should tell me something....

As for the IAC stuff, kinda hard to understand. My startup park position is 144 steps, and the table for warm IAC park steps vs coolant is 125,100,75,50,25,10,5,5,5. I think that is just the stock ARAP bin values. Not sure why this table is needed, since there is an idle speed vs coolant table..... Like if the park position is 144, but the coolant is 133F, does it just move the IAC right to 25 steps, or is that table just the AMOUNT of steps it moves IAC in one shot, at xx coolant?

So for engine crank spark, it just uses the base timing set in dist? Right now i am at 8deg. there are also some hot restart spark scalars...mine is 2.84deg, but it is disabled if coolant is less than 198F. Would that have any affect?

Re: Crank fueling when engine warm.
 

My understanding of that table is it is used at key-on for the desired IAC position. This way a warm engine doesn't rev to the moon on start up. Which is why the counts/steps are lower at the higher engine temperatures.

There has to be an adder to that table as an IAC position of 5 or 10 is too small. But you can still work with that table.

Yes, during cranking the distributor fires at the base setting. The hot restart SA is used to reduce the SA once the engine is running. This helps prevent pinging as the engine catches and revs up.

RBob.

Re: Crank fueling when engine warm.
 

Ok, now i recall the idle flare-up at startup. I think that was a common issue with our cars, and mine had that as well. So maybe that is why my table had been changed. I have had this car so long, i cannot remember everything i have done in the ECM! I will keep chugging along until i nail my long crank times down.....