[Double]

Hey guys. I own a 93 5.2L that has been giving me problems as of late. It's been missing and running kind of rough, and occasionally a minute or so after start up it will die on me. This is really common after the motor is warm.

I tried running it through my area's emissions test just for kicks, and it failed (go figure). So I went ahead and changed out the spark plugs cause it's a cheap fix, but it didn't do much. The original plugs were pretty white, so I know it's getting too much air (or not enough fuel...)

I tried searching on here for an answer, but didn't really find anything very specific for my motor/problem combo. Couple possiblities I've seen though is the PCV valve (which has been replaced a few months ago), the MAP sensor, the crank sensor, the fuel pump (which was replaced two years ago), possibly the O2 sensor...

I'm thinking it's got to be a sensor, because the fuel pump has been replaced, and if it was an ignition problem the plugs probably would've had a lot more carbon built up. So which one? Anyone familiar with this problem that can help me narrow it down?

 

[Canvis]

i would check ur EGR

 

[SOLITUDE]

and your IAC

 

[Angelous]

and your throttle body.

 

[Double]

I pulled out my IAC last night, tested the connections (which appeared fine) and cleaned off the gunk, but it didn't seem to help much. I didn't clean the inside of the chamber very well or do as much as I possibly could with the sensor, but I thought I'd do a little bit to see if it made an improvement

Also, my check engine light is NOT on and I'm NOT receiving any error codes, and from what I've seen that is a symptom of similar problems. Don't know if that little bit of info helps narrow it down at all...

 

[Angelous]

pull off your throttle body and clean the flap really good with carb cleaner.

 

[kevinc]

Mine did the same thing when the butterfly valve was caked in dirt. (The IAC Port was gunked up too.) That = not enough air in the motor. Clean the throttle body. It's really easy to pull off.

Kevin C.

 

[Double]

So I pulled off my throttle body tonight. It had a little gunk built up, but nothing that looked like it would impede the flow of air. Nevertheless, I proceeded to clean it with CRC Carb cleaner. Hit the IAC a little better too.

Got it all cleaned up, reinstalled everything and fired it up. I thought at first it might've made a little improvement, but after about 5 minutes of warming up, it was back to the same nonsense...

It idles right around the 500-800 rpm range, and the rpms are pretty stable there, but the motor is shaking around like it's missing. If I take it up to about 2500-3000 rpm and quickly let off the gas, it just about dies, but usually manages to recover itself. Still no check engine lights.

Any other ideas?

 

[kevinc]

How do your plug wires look? Cap and rotor? Coil resistance? Check em out. Disable your underhood light and run the motor at night (in the dark) and look for blue arcs between the plug wires and the motor block, metal parts, etc. My dad's car did something similar, turned out the plug wire was burned through and was arcing out on the intake manifold, causing a misfire. HTH

Kevin C.

 

[Double]

Would that explain why it runs better when it's cold and worse when it's warm though? It seems to me that if it were a problem with the ignition system, it would run fairly similar across the board at all temperatures. But maybe I'm mistaken...

 

[Angelous]

not usually but a head gasket / clogged cat/ egr would. So would an intake gasket.

 

[Double]

Update

Well it's officially done for. Finally just gave in and took it for an estimate because I don't have that much to be working on it. Piston rings are shot among other things. Basically from what I was told it would be cheaper to just buy a a whole new motor. The damn thing isn't even driveable right now because you can't come to a stop.

Anybody want to buy a 93 Limited??? Hahahaha