Help - at the end of the rope

[misterKTM]

OK - my problem has really elevated...what started out as a heavy lug engine miss and a rough idle is now a barely driveable situation. Anything over a slight throttle load will send it into a missing, stumbling coughing fit. It hasn't stranded me yet, but man - it is not happy at all. Major cut out when you give it hardly any gas....

So...What I've done so far...Checked fuel pressure - all looks good there. With a timing light hooked to the coil lead - I can see the miss in the light - so between that and the fuel pressure check - i'm convinced it is ignition. I did replace the knock sensors - as this was the only code I got. Also replaced the coil - as the resistance on the secondary winding was out of spec - and got worse with heat - but niether of those solved the problem. I'm down to either the ECM or the Opti-crap. I have reciepts from the previous owner that the opti-spark was replaced right before I bought the car, and I've only put 10K on it. There is a vent line coming off the bottom of the opti-spark - so I do think it has been replaced - as '93's didn't come with vents, right ?? The vent line just runs up to the valve cover area though - it is not plumbed into a vacuum source. Plus, I suspect the gal I bought it from had the engine pressure washed or steam cleaned as it was very clean when I bought it.

So - thoughts? advice ? suggestions ? Time to tear the opti-spark out or what ?

Thanks,

rob

 

[muskiemike]

How many miles on the car?

 

[trrgod]

Check if Cats are clogged.

 

[misterKTM]

62,000 miles.

Hmm...cats that is an interesting thought, I've seen a pluged cat criple a big block ford once...but I keep coming back to my timing light on the coil showing a miss - so I really think it is ignition related.

 

[muskiemike]

Not really sure what you have or have not checked, but this 62,000 original miles, one might think that it still has the original plug wires . . .

I have a 84 with 30K original miles and around 25K, it ran like _ _ _ _ I mean real bad, I took it in, they said I needed new plugs and wires, I said come-on, it has 25K miles on it - sure enough, the wires had gotten bad over the years, even though it had only 26K miles on the car.

Just a thought, perhaps you have already tried this remedy!

 

[SPANISHVETTS]

Hi from Lisbon, we´re on a short brake.

3 words; OPTI, OPTI, OPTI! My 93 ate 2, both due to water intrusion.ad

 

[misterKTM]

Thanks for the replys so far guys! I did check for codes - the only one was the knocksensors (43 I think it was). And the gal that had the car before me had reciepts for new opti0spark, new water pump, new plugs and wires, front & rear brakes -the list goes on...part of the plus factor to buying the car - it had a lot of maintanence just done. Also, I checked resistance on the wires - they check out good.

Is there any way the ECM could be causing this problem ? I'm heavily leaning toward the opti being the problem - but am going to really be bummed to take it all apart and find out that it is fine....I've allready done an opti replacement on my '94 trans am a couple of years ago, so I know how much of a pain (and expesive) it is.

 

[Ken]

My vote goes to the cats also. Sounds like a classic case of them breaking up, then plugging up the exhaust flow.

 

[misterKTM]

That would be really cool if it was the Cats - I would sure rather spend money on a new exhaust system than on a distributor...but what about my timing light on the coil lead test - I can see the miss in the light - granted this is at idle - not driving, but it sure seems to point to ignition. I cant think of any good test to do on the cats - suggestions ?

 

[Doutdoor]

I would also think it's the opticrap. Mine went out right after I bought my 92 with 72k miles. The funny thing is, the engine would run ok cold and then start to crap out real bad once it got up to operating temp. I changed a bunch of stuff too. New plugs, wires, fuel filter, new K&N air filter......everything I could think of except the dreaded opti.... $1,250 bucks later replace the opti & water pump. Good luck and make sure they put the vent kit in if yours doesn't have it.

 

[misterKTM]

I think I'm going to tear into it tonight when I get home....Mine to seems worse when warm - it actually does run allright cold.

Who makes the vent kit ??

 

[Hyde]

If not the Opti....

The 93 has a MAP sensor I think. Disconnect it and start the car and see if it changes the condition.

good luck

 

[misterKTM]

Just for anyone interested....it was the opti-spark.

 

[SPANISHVETTS]

Just for anyone interested....it was the opti-spark.

In this short story the Opti was played by Jack Nicholson. ¨It was always the Caretaker¨ When a LT1 runs bad and the motor has been wet replace the Opti. You may have other problems but for sure you need a new Opti. I had 2 replaced on the 93 in 1 year, thank god, both in warranty!

 

[vette-dude]

In this short story the Opti was played by Jack Nicholson.

But did he ever get his Toast???

Randy