Cold Start Stumble/IAC Reset...advice?


Nov 22, 2008
I have an 87 Gn bone stock with 120K on it. I replace the MAF hose, turbo. inlet and outlet hoses (all the above were worn and leaking) New DIS mod and coil, new 8MM wire and plugs.

Before and after replacing the above I still have a cold start stall. The engine will start, tach up to cold start speed about 8RPM? then slow to the normal idle...loop a little then stall out. It can be immediately restarted.

There are no DTC and MIL on. The vehicle idles well when hot. I think I have an IAC issue or IAC adjustment issue. What do you all think?
Do you have any type of scan tool? Whats you coolant temp sensor reading BEFORE you start it up? Could be a IAC issue.
If the TPS is out of adjustment, the ECM may not think its actually idling. Make sure its below .48 with the car running. Sometimes they will float up a little when you start the engine.

Also, if you have a stock chip, the cold start on it was notoriously bad.
yea just haven't gotten there

Yea I know start up ECT voltage and TPS voltage signal are important and I SHOULD have checked them- I just haven't yet... I do have a scan tool- Snap On ETHOS scan tool so I will check them next time I remember to bring it home.

Just between the my Camaro project and Jeep project I get sidtracked alot... the GN is in the garage now.. so I will fiddle with it in a week when I am done rebuild the Jeep from the last adventure- and getting the Z28 back up and running after loosing the CD Module in the dist.

Thanks guys!