Vague & Ambiguous question: cold start idle on 964

[pbs911]

The 3.6 conversion is running great. Exhaust issues are completed, which included hooking up the O2 sensor. When first started the motor hunts up to 1200 rpms. The motor will die if driven cold and the throttle is abrutly lifted. The problem goes away when the motor is warmed up. I am not getting any extra gas via any cold start system. I don't even know where the cold start system is. What should I look for?

[pbs911]

Boy, a guy moves "up" to a 3.6 motor and all he hears is crickets.

[Don Plumley]

creek-creek. creek-creek.

[ischmitz]

Paul,

the cold start function on a 3.6 is realized via the head temperature sensor and the DME. If the engine is cold it'll automactically richen the mixture.

In combination with a lightened flywheel the custom chip you are using might just not be tuned good enough to account for a cold engine and a light flywheel.

IMO, there is not much you can do about it. One would have to dive deep into assembler programming and check how the 8051 microcontroller realizes the cold start enrichment.

Actually you would have to disassemble the code and check where that particular parameter lives in the code or lookup table. Not trivial.

There is a guy (forgot his name) on the 944 board who has completely reverse-engineered a 944 motronic. Everything including schematics and code. The 964 motronic is a newer generation. Still, he might know the answer.