Hey Guys, I just bought a 93 LT 4.3 to play around with. I bought it with the problem it has. It idled rough, surged and even stalled at times when I first got it. I have read all threads pertaining to the CPI Spider and have taken the plentum apart and seen small pools of what looked like oil on the passenger side of the plentum. I cleaned the pools,replaced all o-rings in the spiderwhich had been replaced with a used one prior to my ownership and found several vacuum leaks in the engine compartment. I also cleaned the egr valve and replaced the fuel filter. After all that I started it up and it idled great. I let it idle for about 10 min and then run it down the road it ran great until it warmed up thenit started bogging and eventially stalled (in the middle of the road). It would not restart until I turned the key off long enough for the fuel pump to pump up again. It then started and idled ok but would bog over 1/4 throttle. I babied it home and pulled the round sensor from the top of the plentum to see if there was any excess fuel in the intake and it was as dry as a bone. Please help!!! Only seems to occur after the engine is hot. The plentum being dry makes me think the problem is elsewhere.

Thanks,
John.

 

You asked me if I think it is the cat in a PM. Well, typical catalytic converter type failures/blockages limit RPM. How does it rev? How does the exhaust smell.

Now, given that it is affected by the engine being warmed up, I may be inclined to check out the ignition system. Possibly a problem with the coil or ICM (ignition control problem) that is affected by the heat. On the newer motors, the ICM has a heat sink to dissipate the heat generated during operation. I have seen the conductive grease dry up between the ICM and the heat sink, causing something very similar to this.

Also, check the plugs, wires, cap & rotor for signs of wear and replace as necessary.

Hope this helps.

 

Hey Kyle,
Thanks for the reply. To answer your questions the engines revs fine until it heats up and the exhaust is ok until it warms and then it smells rich. Oh BTW, scratch the cat bing the problem because after I wrote the post I checked the cat and guess what, there is not one... Evidently the previous owner did not see a need to replace it when he replaced the exhaust system. Could that be a problem? Also he only ran a 10 inch pipe with a down spout from the muffler. Could that pose a problem to the engine?

One thing I forgot to mention in my initial description is that the fuel filter that I replaced was full of a tan milky substance, possibly water???

Do you have a troubleshooting procedure for the coil or ICM? Where is the ICM located? I will check the plugs, wires, cap and rotor tonight and get back to you.

Thanks again for the help,
John.

 

Come on guys, I need some help here!!! Does anyone know a direction I need to take here. I am stumped, I have taken everything loose from the plentum and cleaned/inspected it, checked the wires, cap and rotor and nothing jumps out at me. Is there a way to check the coil?

Any help would be appreciated.....
John

 

Fuel contamination may be an issue here. Have a freind help you, disconnect the fuel filter, and direct the fuel into a jar, cycle the key once, and see what ya get. If the fuel is NOT clean, and pristine, empty the tank, flush it out with clean gas, and try again.

 

Thanks Brian, after replacing the fuel filter and seeing the tan milky liquid that came from the old filter it is a possibility that the tank is still contaminated. Can you explain why it onlycuts out and boggswhile the engine is hot andunder a load?

Thanks for your reply,
John.

 

The ICM should be located in the base of the distributor. It'll should look something like this:
[IMG]local://upfiles/667/D1C46B24014D4E8A8D8C7AA8813A4782.jpg[/IMG]

If you follow the center wire from the distributor, it will lead to the coil which should look something like this:
[IMG]local://upfiles/667/6097412A1BDC4CC3B30C995065D58BDD.jpg[/IMG]

Both of these components should be able to be removed and tested by your friendly parts guys at Autozone or Advanced Auto... Atleast they are able to do it on the newer ones...

All images are courtesy of RockAuto.com.

 

Ok all of you guys in bad need of help please whatever you do don't PM the Admin, this is the response you will get. All I did was asked if there was a diagnostic test for the ICM and this was what I got along with the last reply in the post. I didn't even ask where the parts were locatedor what they looded like! I "got my hands dirty" and found them myself. But I wont use any slanderous language just read below, there is enough inthe adminsreply as it is. Iguess I will get booted from the website but if all I get are these kind of responses then I dont need to be here anyway.

Thanks to those of you who did help without an attitude!


From ADMIN:

"I understand your urgency, but to wait around for replies isn't always the best approach, neither is hounding someone for answers... Sometimes you have to get your hands dirty and find the parts people are talking about on your own. Run a search on the forum. If that doesn't garner any answers to your specific problem, run a search on popular autoparts websites to see if you can find what the part people are talking about looks like, then try and find it once you know what you are looking for.

I do not have my references to help you while I am at work and often I do not have time once I'm home as my family comes first. Many of the questions I know how to answer from experience get answered faster because I don't have to look stuff up.

Now, since I'm a kind person, I'll respond to your questions in your post, doing the leg work for you. But please keep things in the forum. Those of us that can help will respond when we can. Everyone here volunteers their time and as such, responses will come when we have time to make them.

Have a read through this --> Guidelines for posting Mechanical Problem Threads

_____________________________

Kyle-"

 

I initially deleted this post, but decided it would do more good left for all to see. For the sake of teaching a lesson, please do detail what is so wrong in the PM I sent you? Please.

For those reading along, here is a bit of back story. I have been PM'd 6 times in the past 3 days by this member and asked questions which I have answered for the most part as well as instructed that these questions should be kept in the open forum. Let me reiterate the reason; so others can comment and benefit from the questions and answers. Every one of my responses to his questions has been kind and courteous and I get flamed in such a manner... Makes me want to puke. Its crap like this that make me question why I even bother.

Also, for the record, you did ask where the ICM was. I answered. You asked how to trouble shoot the ICM and coil. Again, I answered.

Time to lighten up man.

 

Um.... no.....

Although, it is a possibility that when the truck sits, the "contamination" separates out, so there is gas at the fp pickup, and driving it around mixes it up, so it starts to run crappy????

Or: The gas is ALWAYS contaminated, and when running in open loop, it stills runs crappy, just not as noticebly so?


In any event, cleaning out the gas tank certainly won't hurt anything, and will prolly prevent problems further down the road. Once you can get it to go further down the road.....