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Lawn Masters
07-15-2006, 05:53 AM
Is it possible for a car with 228K miles to have an exhaust port clogged up causing a misfire on one cylinder? I have a car here thats doing this to me, and I'm being tormented. its either an exhaust flow issue, or its an ignition issue. I suspect it to be an issue of the cat being plugged up on the motor, which wouldnt surprise me.

as it is, the car will start fine, but it wont idle right, it'll do this misfire and it does it throughout the rpm range, only running on 2 or 3 cylinders. so far, I've cleaned the EGR pipe, valve, verified all vacuum lines are good, compression is good, fuel is getting to the motor well, firing order correct(checked 4 times) new plugs, fresh fluids in everything.

I'm at a TOTAL loss as to what it could be, other than the distributor being screwed up, or the cat being plugged. by how it accelerates in park, I'm inclined to believe its the cat being plugged up.

sawman65
07-15-2006, 06:43 AM
i have a 89 with 260k on it i had the same problem turned out to be the valves i put the shim kit that adjusts them and its all good. mine had the 4af engine but i dont think yous is the same ck the cat first. never heard of the exaust port being blocked up

AAELI
07-15-2006, 06:43 AM
Is it possible for a car with 228K miles to have an exhaust port clogged up causing a misfire on one cylinder? I have a car here thats doing this to me, and I'm being tormented. its either an exhaust flow issue, or its an ignition issue. I suspect it to be an issue of the cat being plugged up on the motor, which wouldnt surprise me.

as it is, the car will start fine, but it wont idle right, it'll do this misfire and it does it throughout the rpm range, only running on 2 or 3 cylinders. so far, I've cleaned the EGR pipe, valve, verified all vacuum lines are good, compression is good, fuel is getting to the motor well, firing order correct(checked 4 times) new plugs, fresh fluids in everything.

I'm at a TOTAL loss as to what it could be, other than the distributor being screwed up, or the cat being plugged. by how it accelerates in park, I'm inclined to believe its the cat being plugged up.
After playing with my son's '88 Toyota corolla that had a similar problem I would suggest taking a closer look at the dist. cap. He also found oil leaking around the dist. shaft causing oil to spread around inside the dist. Other than that I would expect the exhaust odor would be like sulfur/rotten eggs if the cat was plugged.

No expert on these so I'll talk to the kid when he gets back from the dragstrip tonight. Hope it helps.

Restrorob
07-15-2006, 07:49 AM
To check the cat. just loosen the bolts at the exhaust manifold to pipe flange to create a exhaust leak (a bypass). My years as a Auto Tech. I never seen a cat. cause a skip, Just lack of power from being plugged. I would lean towards a ignition or valve issue. The ignition could be checked with a in-line spark tester as used on mowers to determine which cylinder is skipping then go from there.

xcopterdoc
07-15-2006, 08:34 AM
Another quick way to check is to remove the plug wires one at a time to see which cyl is misfiring. If you remove one and there is no change, then thats your dead cylinder. Check for spark, if you have a good spark, check the valves. I've seen dist shaft bearings go bad and cause a wobble which causes a miss. Many things to look at. Also just removing and looking at the plugs would be a way to tell which ones are firing and which ones arent.

fly-4-fun
07-15-2006, 05:19 PM
If the plug wires have 228k miles on them, they might need to be replaced also. Had a problem on my father-in -laws car like this. I did what you did as far as a good tune up, still had problem. It was almost dark when I was about to give up for the day. Started the car with the hood up, and there was little sparks jumping from the plug wires where they were in contact with metal wire looms and other close places. Replaced the wires and it ran like a champ.

Lawn Masters
07-15-2006, 07:19 PM
I found out it was the plugs AND wires. plugs were probably around 15 years old, and likely had 100k on em. wires were probably around 50k on them, but I replaced and both combined made it run perfect again.

Restrorob
07-15-2006, 07:27 PM
plugs were probably around 15 years old, .


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Lawn Masters
07-15-2006, 10:16 PM
I think what gave the wires away on the #3 and 4 cylinders, was the fact that I touched one and got a shock from it just by touching the rubber coating while the motor was running. like i said, its good to go now though.

AAELI
07-16-2006, 01:46 AM
I think what gave the wires away on the #3 and 4 cylinders, was the fact that I touched one and got a shock from it just by touching the rubber coating while the motor was running. like i said, its good to go now though.

I think I would ditto what restrorob depicted. Only I don't know where to find the smiles he displayed!

Good to hear you are back on the road again. I had overlooked the nitetime arc light display troubleshooting method! It works as well as the shocking my arm like wow method.

Dirty Water
07-16-2006, 10:59 AM
I was just about to suggest changing the wires, glad I read the whole thread :laugh:

I had the same problem once.

lawnmaniac883
07-16-2006, 04:18 PM
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Haha....:laugh: :laugh: :laugh: