Alright I've had multiple people try and help me figure this out...and it is just a realllly big pain in my ***. I HATE driving my car because it will never just start like it's supposed to. I could fire off my series1 box the SAME EVERY SINGLE TIME, no matter what weather, temperature, etc. My series2 is DIFFERENT every time.

So here is my cal, let's see if we ALL put our heads together figure this out. I've tried everything, less fuel...more fuel, less timing, more timing, less rpm offset, more rpm offset, etc. etc. NOTHING works.

Here are the issues:
Cold Start (car has been sitting 8+ hours): Cranks 4-5 times, sync's and fires but revs up and dies. If i TAP the gas maybe 5-10% throttle it will catch the drop and idle perfectly from there, and warm up normal.

Warm Start (car has been sitting 1-2hrs, coolant range from 70-140): Car cranks 4-5 times sometimes longer, sync's and fires. Usually wants to fall quick so I have to be ready to tap the gas to catch it, otherwise it revs up to around 1,200 or so and immediatly dies. Every once in awhile it will stumble through it and rev up on it's own. Mostly this is the WORST of my start-ups. It's never consistant and a HUGE headache to try and figure out.

Hot Start (coolant 175+, not sitting long): USUALLY sync's within 1-2 cranks and fires off. Most of the time fires and revs up to idle without an issue or a needed throttle tap. Sometimes for no reason at all it gives the same symptoms as above...revs and dies, needing a quick throttle tap to pull it through.

MODS are:
-FIC 950's on 93 octane only
-single Walbro pump, all stock lines/rail/fpr
-AMS VSR w/stock throttle body (emissions gone, but all TB accessories there)
-Kelford 272's
-Stock block/head
-Small battery

 

1. have you tried a different iac? not sure if the unit your using is on the way-out & only works well when everything is up to temp.

2. can you gather a internal log of you engine cranking / starting up?

 

IAC is good, first thing I checked coming from the good ol' DSM days.

I spoked with the AEM techs and this is what they told me.

The way Series2 sync's is different then Series1. For this reason the Crank Injection Time table is basically useless. Series2 mostly uses the Initial Crank Pulse table. When cranking, if it misses that initial sync (1-2 crank period) it then reverts to the Crank Injection Time but still has the initial pulse fuel dwelling...which would cause rough starts.

So basically you have to tune the Initial Crank Pulse table, but here's the thing. It is EXTREMELY sensative. So sensative that only ONE click one one direction or another will cause the car not to start correctly. You literally have to be perfect, and what's worse is there is no way to "tune" it. It's just a guessing game with trial and error.

How awesome of AEM huh?