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

[jimilane]

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

 

[jrichker]

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.

 

[jimilane]

That was the first thing I cleaned.

Maybe there's still a little dirt or something in there making it stick.

I cleaned it with brake cleaner.

Thanks,
Jim Lane

 

[HISSIN50]

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

Good luck.

 

[jimilane]

Well....I have a code 12....rpm unable to achieve upper test limit....I've had that going on for three years now. Haven't really had a problem with the car though....and there are other codes that have been there for a while...EVP 34, air machine codes, stuff that isn't there.....there are no new codes.

I'm cleaning the IAC really good. There is a build up on the plunger that I'm working on. I'm going to take an IAC off the other car and check it out too.

Jim Lane

 

[18mustangs]

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

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

 

[jimilane]

Ok, I think it's fixed.

I kept getting the code 12. The Actron CP9145 scantool that I was using couldn't run the tests because it couldn't control the rpm. This was caused by the IAC not working correctly.

I cleaned the IAC, then I was getting a code "0". It says it doens't know what the code is, but there is a problem. Anyway, I got a new IAC and took a look at it. It turns out that the spring in the old IAC was about worn out. The plunger on the old one was very easy to move compared to the new one. I then replaced the old IAC and the code went away and the engine idles a lot better.

I bet it starts right up tomorrow.

have a nice day and thanks for the help

Jim Lane

 

[87'GTstang]

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.

 

[jimilane]

yep, it was a IAC. The new one did the trick!

The car runs better for sure.

Probably not the injectors. It still pulls hard through 6000rpm.

jim