Misfiring only after hot restart

[gregzbutt]

Hello! I have a 91 4 cylinder with a 5-speed, and 187k miles on the odometer. About a week ago I was driving to work, stopped at a gas station to get a cup of coffee, and then noticed the engine running really rough after I restarted it. It felt like the car was running without a cylinder. I pulled plug wires and noticed no change in how the car ran when I pulled the wire for cylinder #2. After work, I fired the car up and it ran absolutely fine. The next day, however, the same thing happened. I started my car, it ran terrific, but then after I restarted it after visiting the grocery store, it starting misfiring again with cylinder 2 not firing.

Today I replaced the distributer as the old one was leaking terribly internally, and the coil was also shot. After seeing how bad the multiple cracks in the coil were I thought for sure that was the issue and the new dizzy would solve my problem. I then took the car for a test drive to the beer store, but I got the same misfiring problem after I restarted the car for the drive home.

So now i'm not sure what to do next. I was thinking about replacing the cap, rotor and plugs, but the problem only occurs when the engine is hot, and only after I restart it. I have never noticed any intermittent misfiring ever, although the engine does run a lot smoother now with the new distributer.

Might this issue be fuel related? I have heard that this might be a symptom of a fuel pump getting ready to die. Maybe problems with the injectors? Maybe a mischievous temperature sensor sending silly signals to the ecu? I'm wondering if anyone else on here has had similar issues and what steps they have taken to solve the problem.

As always, thanks so much for the help!


Greg

[mcx]

i would check the display for stored trouble codes...go get the paper clip!

[gregzbutt]

Ok, I got 2 flashes, then 4 before a long pause. Code 24 deals with the intake air temp sensor signal.

[mcx]

Originally Posted by gregzbutt

Ok, I got 2 flashes, then 4 before a long pause. Code 24 deals with the intake air temp sensor signal.

ok..disconnect the harness to sensor and clean up the electrical connections and check for broken wire....now pull the sensor out of the air cleaner housing...go get your multimeter and put it on ohms...take test readings with the sensor cold and hot[use a hair dryer]...if out of spec,replace.

[gregzbutt]

I won't have a multimeter until Wednesday, so I won't be able to check it till then. I drove around for a bit today, shut the car off, and restarted it about 10 mins later. Sure enough, started misfiring again. I went through and verified that I was getting spark at all 4 cylinders, which I am. So that leads me to believe it's a fuel issue, unless maybe this air temp sensor is sending weird signals to the computer. I'm completely dumbfounded by this. It doesn't make any sense to me as to why the car will run perfectly fine until I shut it off for 10 minutes and restart it.

[mcx]

Originally Posted by gregzbutt

I won't have a multimeter until Wednesday, so I won't be able to check it till then. I drove around for a bit today, shut the car off, and restarted it about 10 mins later. Sure enough, started misfiring again. I went through and verified that I was getting spark at all 4 cylinders, which I am. So that leads me to believe it's a fuel issue, unless maybe this air temp sensor is sending weird signals to the computer. I'm completely dumbfounded by this. It doesn't make any sense to me as to why the car will run perfectly fine until I shut it off for 10 minutes and restart it.

the sensor is probably giving a wrong reading as it get fully warm from when the car is shut off and heat soak sets in....when the car is cold the sensor is probably within spec so that is why it runs fine initially...get the meter and check the readings.