Please help me before I lose the little hair that is still on my head!, I have this issue for many weeks now with no solutions so far. I got a '71 Firebird Formula with a LS3 based 416 and a GM engine controller kit (part number 19354332), I got the car tuned by a friend of mine using EFI Live (where I live there are no professional tuners for GM cars), the car ran great and got pretty good numbers on the dyno, the issue I have now is the cold start, sometimes it will never start what so ever, sometimes it will run for half a second and then die and will keep doing this for 5 or 6 times in a row before it run poorly for another 5-6 minutes, and during that it will choke and die if I give it some gas. it will finally be ready to drive when it picks up some coolant temp. The dude that did the tune had a look at it and said everything seems fine and I should look else where. since then I removed the whole engine harness and installed it again after cleaning all the connectors and adding a few more ground straps. still no change!, I have attached two log files, one when its cold and hesitate to run, and the other when its running but won't repond well to the gas pedal, and also attached the tune file. This is not my first LS swap, so I do know my way with these cars.

Engine specs :

LS3 block, with 416 rotating assembly
PRC 237 Cathedral port heads - 11.1:1 CR
Camotion Torquey Stroker camshaft - 234/242 @ .621"/.604 -114 LSA.
FAST intake with NW102 DBW TB.
Magnum T56 6 speed.

 

Return the open loop tables back to stock. As there is no cold start enrichment the way yours are set. Also need to add to the start up idle speed, your at 800 rpm.

Also the desoot mode should be disabled before tuning the Maf table, that's why there is a hump in the 7650 hz to 9300 hz cells of your Maf table.

Russ Kemp

 

I tried to do what you pointed at, I'm not familiar with the whole ECU tuning things so I did my best, the car started right up from the first turn of the key and idled fine at about 1000 rpm!, I have attached the tune and a log of the start up, can you please have a look at it and let me know if this is all what it needs to be?

Thanks a lot buddy!, I wasn't expecting any easy fix for it!