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As posted previously, opti and plug wires were replaced a few months ago on my 95 LT-1 with about 41,000 miles. The missing slowly but surely returned (actually worse than original) so I finally got around to dropping it off again at the dealer. Based on feedback from some of you I was suggesting that they check for blocked cat, bad injector, bad coil, etc. assuming that there was no way it could be the opti. WRONGO--the dealer said the cap was bad and also asked if I cleaned the engine (steam clean or direct water). I told him I did not and he said there was water in the opti.
How could this be--I thought the 95 had the special vent setup to keep moisture out of the opti? I am very concerned that there is something else going on to result in a failed opti in 4 months--unless the opti that was put in was somehow defective. And yes, the water pump was replaced a while ago so I cannot figure out how water would get into the opti.
The water pump was replace a couple of years ago and the opti was replaced four months ago. We haven't seen rain in southern California since last year. After thinking about it a while, I am suspicious about the dealer claiming there was water in the opti since he said they would probably need the car until 3:00pm today to do the job. Seems to me if they had actually removed the opti for inspection, then installing a new one would only take a couple of hours. I wonder if they were just assuming failure due to water and then tried blaming me for steam cleaning the engine so that they would not have to cover the part. I have never steam cleaned and I make sure water does not go anywhere near the opti. I suspect the opti that they put in 4 months ago was somehow defective and/or the vacuum lines to keep the opti ventilated were not installed correctly.
Either way, it is disconcerting that this seems to be such a failure-susceptible part.
Re: Engine miss continued--OPTI AGAIN!! (DougSilver)
Be sure to get the old opt back. It's possible that it failed (I had one that had corroded distributor contacts, not an OEM cap :mad ), but I doubt it would get any water in it in 4 months that would cause it to fail unless someone forgot to connect the vaccum tubes.
Trouble is, that if the dealership screwed up, you'll never know.
IMHO: A 95 opti shouldn't fail in 41K. I'd be very suspicious of that dealership. Sounds like something else is is wrong.
Re: Engine miss continued--OPTI AGAIN!! (John Row)
Even makes me wonder if they actually replaced my original opti 4 months ago. What happened is that I was quoted $800 for the repair but I found that the opti is covered for 7 years/70,000 miles in California. So suddenly they (or GM) had to cover repair.
Yes, check the coil/coil wire. I thought my problem was the Opti until I undid the coil wire. A previous owner noted in the book that he changed the water pump. When it was leaking it must have corroded the wire. When you get it back, check to see if they changed anything else.
Re: Engine miss continued--OPTI AGAIN!! (DougSilver)
You are aware that the water pump has to be removed to get at the opti. When I had the pump removed water/antifreeze got into the opti and it got replaced also.
No--I didn't realize that the water pump was being removed and replaced. I am not so concerned about getting another opti, since it again will be on GM's nickel and I suppose if it fails again, they will be replacing it again. It just seems that something was done incorrectly in the first place which does not give me alot of confidence that they will get it right this time either. Aren't there any decent Chevy dealers out there?
Re: Engine miss continued--OPTI AGAIN!! (DougSilver)
this sounds like a part failure.
it just does not sound like anything else but....
the pump has to come off, so does the harmonic balancer... and yes, you can pack rags over the opti to protect it from water damage when the pump comes off.
also, have them seal the opti with RTV where the cap meets the body.
End of the saga (hopefully). Finally got my car back today and their diagnosis was "scoped engine and found spark plugs fouled from crossfire and bad engine miss". Consequently, they replaced the spark plugs in addition to the opti this time--all at no charge. This diagnosis is similar to the one 4 months ago and at that time they changed the opti and wires but not the plugs. Seems like they finally figured out the plugs needed to be changed as well.
The car finally runs great (as it should with new opti, wires and plugs) so I can finally get around to doing the mods that have been sitting in my garage for the past year--1.6 roller rockers with springs and shorty headers.