Okay, it's been a tough week. I have been dealing with a hesitation and smooth idling problem. After some inspection, I found that the coil was arcing to the block and messing up. I went to Autozone and got a new coil and installed it. Not bad for a rookie. Just gave up a pound of flesh getting it in! But wait .. I still have a hesitation problem. :confused:

It appears when the motor is hot or when I hit the gas over 2000 RPM. It hesitates. A little around 2000 (cruising range at 85 MPH :mad) and so bad that I can't get the engine to rev over about 3200 or so. Not cool at all! I have checked in the dark and I don't see any arcing and everything is good and tight. I am wondering if there is another problem -- but what? Any ideas? I am on a budget and hate to take the car in but I have had one suggestion to get it scoped but I want to use the car here. Help!

 

that sounds like the main symptom of a dying opti-spark.

how many miles?

 

Just turned over 90,000 miles. :smash:

 

Have you checked for codes? TPS and fuel pressure are 2 things I'd check right off.

 

Is it backfiring out the exhaust after it misses? If so then you are not getting any spark and the gases are igniting in the exhaust...

 

Tough to tell. It is definitely hesitating and rough. I had it in park and revved it and it would not go over about 3500 RPM. It was hesitating, coughing, and not having fun.

 

Not sure if it's related, but when I first got my car I couldn't rev over about 4 thousand. I didn't really try it in park though.. anyway, my cats were clogged up. I opened them up to let my car breathe and the problem went away.

Just for what it's worth.

 

Have you recently replaced the spark plugs?? That can also be caused by too much spark gap. Factory coil just can't keep up at higher RPMs. :seeya

 

With the info about not being able ot rev above 3500, I'd say plug cats.

 

:confused: Plugged cats! How do they get plugged? I use good quality gas and drive an hour each way on a regular basis. How do you check for plugged cats?

 

When I received my 92' it had around 84,000 miles and less than 2 months after, around 85,000, my car started doing the EXACT same thing as your car is now. When the car was started cold, it was fine, and you could accelerate hard and climb the RPM scale no problem. When it was hot however, the car started to hesitate when you accelerated, then choke, cough and studder in higher RPM's. Soon, when it got even hotter, the car would NOT go above 3000 RPMs (for me at least) no matter how hard you hit the gas. (And towards the end of the Opti's life, it would start to stall and posses horrible idle, like not above 1500 RPM's)

Sounds like it is a bad Opti-Spark, if it does it everytime the car gets only to a hot temperature, then an Opti-Spark might be your problem. I could be way off, but I have had experienced in clogged cats before, and engine temperature usually does not play a huge role. Usually your car performs horrible from start-up, correct? (Please correct me if I am wrong)

My 92' came from Florida (and from what appears to be where you are loacted) where humidity is in abundance, a non-vented Opti's nightmare, and my Opti bearing became frozen due to rust and corrosion. I would check the cats first, cheaper and what do you have to lose, but if they check out alright, an Opti Spark would be my best guess.

Hope some of this helps! Take Care. :seeya

 

Plugged cats are caused by contaminants getting on the catalyst and causing it to overheat and melt, plugging all the little holes that the exhaust is supposed to travel through. Take it to an exhaust shop and they can test it.

J :seeya

 

If you're not the original owner, could be someone else used avgas or hi-octane leaded racing gas in the past. You'd be just the beneficiary of the misdeed.

That said, have you ever had the opti replaced? 90K would be a high average for failure. Does the water pump weep hole indicate any problems?

 

I had the water pump replaced at about 60k. The car's been mine for almost 3 years and 40k miles so I really doubt it is the cats. I am pretty sure the opti is original however I don't know if the previous owner replaced it.

And yes, I am pretty sure that the weather here is contributing to killing the opti. It is near 100% humidity for about 8 months out of the year in Tampa and we just finished up our summer rainy season. I had thought that I had survived another season -- after all it is dry now 30-40% humidity. What is the damage on an Opti replacement? From what I have read, it is not a novice project.

 

Humidity might be a cause, but it usually takes an anti-freeze bath to do it.

A new opti is about $240 (Jeff Kopp, plus a few bucks shipping). Plus you'll need $20-$30 worth of common tools and new water pump gaskets ($2-$3).

As far as DIY, yes a novice can do it. If changing a tire is a 1 and installing twin turbos is a 10, then replace the opti is a 2.5 . It takes more time to figure out how to get sockets on bolts than anything else. Although with 90K you'll need to work for a good hour to get the dampner off. I did a step-by-step file for someone. If you would like, I'll email it to you to get an idea of the job.

A recent Corvette Fever there was a good pictorial on doing this job. Go to www.corvettefever.com/ hit SEARCH, type in OPTI then select the article in the "How-to" section (note: you may have to join the http://www.corvettefever to get the search to work, but it's free).