Dies after start, restart, then fine...why?

Remove, clean & check the IAC (aka IAB). An engine that dies or stalls when cold is likely to have a malfunctioning IAC.

See http://www.veryuseful.com/mustang/tech/engine/ for location of the IAC & 10 pin connectors and lots of other useful stuff.

Have you retrieved the codes yet? The man who posted above me has some nice links for doing so.

Good luck.

jimilane said:

I have two Mustangs. 1990 and 1993. Now they both like to die right after start. When you resart, they both run fine. I'm not using any additives, just pump gas....and that gas comes from different sources. I haven't modded both cars the same way...they have different set ups for the engine.

Fuel pressure is up. I have changed fuel filters.

I'm thinking injectors clogging or something.

I can't figure this one out.

All the connection to the injectors are good.

Spark plugs check out.

This is just a weird thing...

The injectors are the 19 lbs and I have no idea how old they are....probably original.

thanks
jim

Click to expand...

Where is your idle set at? My car did that after my intake swap and idled at 650 RPM. I adjusted the idle to 750-800 rpm and the problem went away.
Tim

You know the IAC is an electrical device, it DOES wear out over time. Simply cleaning it just doesn't do it sometimes. If the job is does thouroughly and very well, then i'de start blaming the unit One of the tasks for the device is that when the key is turned to the run position, the ECM tells the valve to open the bypass port holes more to help get the things started (getting fired up and staying running is all the ECM is concernec with at this point). If it is not working properly, when the engine starts there is a great demand for air, when it is not there via the IAC or IAB valve, it has no choice but to nose over and stall.

If the injectors were clogging, you would definitely know it the entire time the engine is running including anytime you wanted passing power.

Another little test you can do to see if it is working is to go all out WOT in the highway then just quickly step off of the accelerator pedal. The RPMs should slowly come back down, if they instantly drop very fast including surge to the point whre it drops below idle speed abruptly, then I would look to replace it.