Tyring to help out a friend with his 85 Vette. He is running a Super Ram (no cold start injector), Accel 219 cam, 350 with L98 aluminum heads, and 24 pound injectors. His pretty much worthless Diacom data shows a BLM of about 114 - 118 at idle. It also shows zero spark advance which I thought was wierd. I sent him a new 85 bin with a little fuel taken out of the idle area in the MAF table plus programmed in spark advance tables from my $6E bin I was running with aluminum heads and similar cam. He claims performance is greatly improved but the idle is oscillating when cold and is so rich its literially choking him. I have heard that playing with the injector constant is trouble with this code. Tunercat and GMEpro display the injector constant as 15??? What is this about? His GMs per second at hot idle are about 9.

Anyone have any ideas what would be causing this rich idle? I would not expect a BLM of 114-118 to run that rich when cold the way he is describing. He has plans on upgrading to $6E code but I want to learn more about the 870 ECM.

 

That is what they had to tell the ECM the engine had for injector size to get the correct fueling. Running an injector constant of 15 with 24# injectors is where the extremely rich idle is coming from. If you can, try setting the injector constant to about 22 and see what that does for him.
The idle GM/sec of 9 is about right on the money.

 

My point is that even the stock bins, GMEPro displays the injector constant as 15. Tunercat does not even have a table for injector constant in the $1F TDF file.

 

I know, thats what I was saying. GM put in an injector constant of 15 to get the 19# injectors to supply enough fuel for the engine, from the factory.

 

thats so funny about the injector constant. $1f doesnt use one its uses a table called

pulsewidth vs loadvalue

this table will show injector pulsewidth in usec vs LV8.

just look at it this way is its 1234 usec it really 1.234 millsec.,

also if its that rich might i suggest dropping the 0,16,32 lv8 usec values by say 7% or so. thats if the blm is reall 118-114.

peace otu it you need more help just email me. ive got alot of timie playing with this particualr code.