ECM?

[acooper198201]

Hello, I have been away for awhile, but now I ready to get back into my 93 festiva … It runs and drives "ok" but, it runs rich as hell and sort of floods out … What I mean by that is when you start it for the first time of the day, it starts just fine. After you run it for a little bit you have to mat it to the floor to get it to start. I can also smell gas and my MPG is down to 30 … question is this, if F.R.E.D.(f**king retarded electronic device) is dead, will it still run and could a bad ECM cause a run rich condition?

[Team Lightning]

If it’s been sitting for a while, the injectors might be sticking open. How long since it’s been run and driven?

[acooper198201]

I have been driving it daily (110 miles), I ran a full tank of gas thru it with 3 bottles of injector cleaner about a week ago... no change. I was thinking it might be like some of the old carbureted systems where when the ECM died it just held a solenoid fully open. I had that with an old Camaro one time and had to use some creative manual adjustments.

[w4rkry]

I would try unplugging the ECT (electronic coolant temp sensor) in the intake manifold (green plug right behind the passenger side injectors).
The ECT sends the coolant info to the ECU to adjust the air/fuel ratio. When it goes bad, the car will pick the wrong fuel map (like a very rich one for cold starting) even when the engine is hot. This causes the exact issue you have, very very rich conditions when the engine is warm, making it hard to start, requiring you to floor it.

Unplugging it will make it run a default in-between AFR. If that seems to help, get a new sensor, they are less than $20 at most places.

[acooper198201]

thank you, I will try that tomorrow.

[acooper198201]

so I unplugged the ECT... difference is amazing... thank you very much. Looks like I will be driving it with it unplugged for a few days till the new one comes in... no one seems to have them in stock, I wonder why...lol

[w4rkry]

so I unplugged the ECT... difference is amazing... thank you very much. Looks like I will be driving it with it unplugged for a few days till the new one comes in... no one seems to have them in stock, I wonder why...lol

Awesome! Glad to hear it worked!