1993 LeSabre Idle Rough after Code 18 After Repairs - Page 3 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 01-09-2012, 01:49 PM   #21
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Originally Posted by Smokerll View Post
If it was me, I'd put the old gear back on. Whats a smidge? If the timing marks were lined up on first inspection then I would think things in that area are ok, and who knows what that new gear fits. If it was off just a smidge, if its a small smidge I doubt that it would cause it to run that rough. While your in there you could put a new chain on. You didn't say anything about checking injectors or spark plugs. My guess is you will find a dead cylinder or two.
You have to go back to the top of the post. The car has new wires and plugs are two years old. A dead plug or injector would not set the CODE 18 error.

The new gear is the right one for the car. However, who knows what quality control is like these days. I replace the motor mount on the drivers side at the front of the car last year and the replacement was a piece of crap that I had to re-machine to get to fit and it was a $47.00 part; it was made in China. The gear set came from Advance Auto.

I think I will put the old cam gear on and the old crank gear on and see how they align up. It is possible that things moved a bit on me. If the old gears timing dots line up and the new don't, then I will know it is a machine error.

A smidge is like maybe a 1/16"? or maybe less. The teeth on the two gears have to be in align or the key-ways will be off enough to prevent sliding on and I think that is what I am seeing, just enough off that the gear won't slide onto the key on the shaft. If it is only off that much, then moving the crank shouldn't be of any concern is what I am thinking.
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Old 01-11-2012, 01:24 PM   #22
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I wonder if the alignment issue is from chain stretch? Old chain comes off, the stretched chain is slightly longer than the new not stretched chain. That would just be a matter of adjusting the alignment slightly, and the gears would still line up like they should.
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Old 01-11-2012, 06:14 PM   #23
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I wonder if the alignment issue is from chain stretch? Old chain comes off, the stretched chain is slightly longer than the new not stretched chain. That would just be a matter of adjusting the alignment slightly, and the gears would still line up like they should.
I decided to take the *.A. Gear set back and ordered a Cloyes set. I was reading at a high performance forum that some had had problems with the *.A. Gear including one that said he got a gear that the hole was off-centred and some thought that the chains were lower quality. It will take a few days for the new set to arrive and with free shipping and no tax it is only going to be about $5.00 higher. I will post after trying the Cloyes set.
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Old 06-17-2015, 04:43 PM   #24
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HI,

I know this is an old thread, but I recently had exactly the same symptoms: Code 18, engine running rough The symptoms started towards the end of a 250 mile drive. I'm curious how your problem was resolved.

In my case, I first followed the procedure in the FSM, but everything checked out OK. I even verified that the cam/crank sensor and cam/sync output signals were all good with a 'scope. After doing that I cleared the codes to see if 18 would show up again, and it did. I then moved on to checking for spark at each cylinder. I don't know when the plugs were last replaced, so I replaced all of them first, and found that whoever did that last time hadn't fully seated the plug in cylinder 5 and the gap was filled with carbon. Replacing the plugs improved things somewhat, but the roughness remained. I cleared the codes after doing this and couldn't get code 18 to show up again. Further testing showed that the 1/4 coil wasn't producing a spark. Replacing that coil has fully resolved the problem.

I don't know why a bad coil and bad plug caused code 18.
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Old 06-17-2015, 05:25 PM   #25
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It is triggering a misfire but the computer does not know how to interpret the problem as such; this models don't have a code for it, so it sets the code 18. Another person had a bad wire that triggered a code 18 on these models. In my case, a bad ignition wire triggered a code 19 instead of a code 18; the code 19 showed up after I replaced my coils and I traced it to a bad ignition wire. Newer cars have more sophisticated computers and can sense a wider range of problems. For example, on my current car, a 98 Buick LeSabre, the previous owner had replaced a bad coil that showed up in the trouble codes. There is no code for a misfire on a 93 Buick LeSabre.
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