Engine I am having trouble with the engine in my 1991 Mustang.

[AeroCoupe]

It’s an A9P series ECU which is for an automatic transmission. What transmission do you have in the car?

 

[sands9330014]

It’s an A9P series ECU which is for an automatic transmission. What transmission do you have in the car?

It is an automatic car.

 

[AeroCoupe]

With everything you have done and not getting any codes for O2 sensors reading rich I just keep coming back to the ECU needing to be sent to ECU Exchange.

 

[sands9330014]

With everything you have done and not getting any codes for O2 sensors reading rich I just keep coming back to the ECU needing to be sent to ECU Exchange.

Does the BAP sensor have anything to do with it?

 

[Mcmahst]

I’m just wondering, if this is a 91 Mass Air engine swapped into another vehicle, if all of the grounds are property installed? Like the one for the O2 sensor harness, the one for the ECU, etc. Missing grounds can look like ECU problems. Just a possibility.

 

[sands9330014]

I’m just wondering, if this is a 91 Mass Air engine swapped into another vehicle, if all of the grounds are property installed? Like the one for the O2 sensor harness, the one for the ECU, etc. Missing grounds can look like ECU problems. Just a possibility.

This was a kit car but it worked properly.

 

[Noobz347]

I'm going to go with wiring and connections issues.

Something is misfed in the harness or a stray path to ground is being found like @Mcmahst suggested.


Other things that come to mind:

Why was the car parked for so long? Was it because of a malfunction?

Did you ever get to the source of that malfunction?

Bent rod generally indicates a cam/timing/valve interference problem.

Do you happen to know what maintenance was done or attempted prior to it getting parked?


At this point, I am going to recommend that you go through the, "Surging Idle Checklist".

Thread 'Help me create the "Surging Idle Checklist"'

Apr 10, 2005

Updated 05 July 2022 to add rough idle when cold and smooth idle when up to normal operating temperature. See the EGR tech information, section #15 for more help.

Many of you are familiar with the "Cranks OK, but No Start Checklist for Fuel Injected Mustangs" checklist and the No Crank Checklist. They are very effective in finding and eliminating the problems by use of a systematic process that checks and eliminates possible causes. This idle problem checklist will use the same troubleshooting strategy and methodology.

By the term surging idle, I mean an idle that...

• jrichker
• 1986 1993 86-93 check engine light code 67 cranks ok dump codes eec-iv mustang no start
• Replies: 575
• Forum: Fox 5.0 Mustang Tech

• 

Let us know what portions of these tests are bad and give a shout if there is some portion of the checklist that gives you trouble.

 

[Mindseye007]

When the engine of my car gets warm, it starts idling very poorly and the engine stops.
It won't even restart. At that time, I measured the ECT voltage and Ω. 4.8kΩ for 1.2v.　　n the scanner tool, 40, 15, and 12 returned, but they disappear again.
I measured the compression again, checked the plug (black), and tried installing a different plug cord, but the symptoms are the same.

View: https://youtube.com/shorts/WeLeM2Z8VFg?feature=share

What is the timing set at? Sounds off to.me...