1991 L98 engine runs rough
5th Gear
Joined: Jun 2011
Posts: 5
Likes: 0
Okie, sorry this reply made a bad turn.
To all the guys with the computers and programs to diagnose engine problems - I don't have the diagonsotic tools to find my problem. I read the forums to get information to make decisions on what the problem may be. I have replaced a few parts that I didn't need over the past 5 years since I bought this Vette. They probably would need replacing soon since the car has 108,000 miles. As I said earlier, I spent $275 at a Chevy dealer that specializes in Corvettes and they couldn't fix the problem. I got information from the forum and found the problem with the help of forum members. I have spent a lot less money by getting help from the members and replacing a few extra parts. I don't really want to be an expert on L-98 engines. I just want my car to run good.
If Okie and I replace too many parts, then there are less parts to replace in the future and we will reduce the probability of a breakdown in the future. Just my opinion.
Thanks, Mickey
If Okie and I replace too many parts, then there are less parts to replace in the future and we will reduce the probability of a breakdown in the future. Just my opinion.
Thanks, Mickey
Burning Brakes
Joined: Aug 2010
Posts: 833
Likes: 1
Well, that is where you fools go, the lottery. I have just gotten 5 emails from an attorneys in Nigeria. Well, I'm going to be rich. I will be so rich, when my C4 has a problem, I can pay someone else to throw parts at it. In fact, once all my money comes in, I will be hiring someone to type my posts for me.
Lottery? Why take chances. This is a sure thing. I'll buy Vivid Entertainment and all the girls who work there will have it in their contract to spend a night a month with me. I probably won't even have time for you common folk. I'll be with the rich and famous.
I might even hire someone to fix my cars by Ouija Board. We'll ask the spirits what part to replace. "Oh Great Spirit. My car doesn't start. What to replace?". Answer: Blinker Fluid.
Lottery? Why take chances. This is a sure thing. I'll buy Vivid Entertainment and all the girls who work there will have it in their contract to spend a night a month with me. I probably won't even have time for you common folk. I'll be with the rich and famous.
I might even hire someone to fix my cars by Ouija Board. We'll ask the spirits what part to replace.
"Oh Great Spirit. My car doesn't start. What to replace?". Answer: Blinker Fluid.
Drifting
Joined: May 2006
Posts: 1,428
Likes: 7
From: Chewelah Wa
I am of the "If it ain't broke, try not to fix it" crowd. Sometimes you end up replacing a 20 yo part with 10 years left on it with a new part that lasts 6 months. I realize that sometimes you just have to take your best guess to solve a problem in a timely matter.
As for the OP, see if your shutdown happens at a specific coolant temp (a/c on)...this would be a sign that it is a heat soak electronic type problem....and do the FP checks at failure.
As for the OP, see if your shutdown happens at a specific coolant temp (a/c on)...this would be a sign that it is a heat soak electronic type problem....and do the FP checks at failure.
5th Gear
Joined: Jun 2011
Posts: 5
Likes: 0
New Parts
If new parts only last 6 months, then we are all in trouble. Even if I had a expert mechanic replace the right part the first time and it only lasts 6 months then we will all be replacing parts every 6 months!!!!!!
Mickey
Mickey
Team Owner
Joined: Jul 2004
Posts: 28,475
Likes: 3,291
From: Hartford WI
To all the guys with the computers and programs to diagnose engine problems - I don't have the diagonsotic tools to find my problem.
I read the forums to get information to make decisions on what the problem may be.
I have replaced a few parts that I didn't need over the past 5 years since I bought this Vette. They probably would need replacing soon since the car has 108,000 miles.
As I said earlier, I spent $275 at a Chevy dealer that specializes in Corvettes and they couldn't fix the problem. I got information from the forum and found the problem with the help of forum members. I have spent a lot less money by getting help from the members and replacing a few extra parts. I don't really want to be an expert on L-98 engines. I just want my car to run good.
If Okie and I replace too many parts, then there are less parts to replace in the future and we will reduce the probability of a breakdown in the future. Just my opinion.
Thanks, Mickey
I read the forums to get information to make decisions on what the problem may be.
I have replaced a few parts that I didn't need over the past 5 years since I bought this Vette. They probably would need replacing soon since the car has 108,000 miles.
As I said earlier, I spent $275 at a Chevy dealer that specializes in Corvettes and they couldn't fix the problem. I got information from the forum and found the problem with the help of forum members. I have spent a lot less money by getting help from the members and replacing a few extra parts. I don't really want to be an expert on L-98 engines. I just want my car to run good.
If Okie and I replace too many parts, then there are less parts to replace in the future and we will reduce the probability of a breakdown in the future. Just my opinion.
Thanks, Mickey
It would help narrow it down further if there was some data feedback. Quite often a lot of things are subtle and you don't know it till it is way too far gone.
108K is not a lot or is too much depending on the kind of driving you do.
A dealership cannot specialize in anything much. It is up to the tech. If your tech is a fresh graduate of Lube Tech, it doesn't mean squat. I had a couple of techs that couldn't figure out what was the problem with something. I brought it to HiTech Motorsport and Brian Ebert figured it out in less than an hour looking at scan data.
And if you drive the car over a cliff, claim insurance and buy a totally new car with a warranty, you won't have any issues. When a problem arises, send it in and they fix it or lemon it. Why not replace every bolt from stem to stern. That way it will have a few years before it seizes up? Every sensor too? I had a distributor that ran over 120K and was still fine. No play in the shaft. OTOH, my Vette distributor that was also OEM had issues.
Drifting
Joined: Feb 2006
Posts: 1,263
Likes: 0
From: CV ca
St. Jude Donor '11-'12-'13
Instructor
Joined: Aug 2009
Posts: 169
Likes: 7
From: Pittsburgh PA
pressure check
I bought my wife a 1991 L98 Corvette coupe back in February 2010. It ran great, looked good. Later on in the year, it started running rough and dying in traffic. I changed the spark plugs and wiring. It helped but still did it. I changed out the fuel injectors and replace the TPS, MAP sensor and went through the vacuum lines looking for leaks. Still does it. I went through the codes looking for something and nothing came up. I'm now thinking about the chip in the ECM and the ignition module as that's only thing that I haven't touched. It gets even worse when the AC is on. Sometimes, it runs great for about 15 minutes and then goes rough. Any thoughts on the rough running?
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Burning Brakes
Joined: Apr 2009
Posts: 877
Likes: 0
From: Broken Arrow Oklahoma
I fly jets for a living. Let me ask you a question. If you have a component that is near its service life, do you
a. Keep the component running until it fails or
b. Change it out.
Depending on where you are, it could be a big problem. At 37,000 feet, you don't want old parts in your aircraft that are that close to service life. I take the same view with my cars. Parts are cheap. Life isn't. This process has been going for over a year now. My wife drives this to OKC and back. I want to make sure she arrives and returns.
a. Keep the component running until it fails or
b. Change it out.
Depending on where you are, it could be a big problem. At 37,000 feet, you don't want old parts in your aircraft that are that close to service life. I take the same view with my cars. Parts are cheap. Life isn't. This process has been going for over a year now. My wife drives this to OKC and back. I want to make sure she arrives and returns.
Burning Brakes
Joined: Apr 2009
Posts: 877
Likes: 0
From: Broken Arrow Oklahoma
while I am at it, this guy came here for some help and the usual crowd decides to tell him he spent to much money on parts. I don't recall anywhere in his post that asked for an opinion on that subject. I doubt that he returns and I wouldn't blame him.
5th Gear
Joined: Jun 2011
Posts: 5
Likes: 0
Thanks to Forum Members for the help.
RLG, thanks for your support. JetJock, Okie and I read the Forums for information and help. We may change parts to eliminate a problem but with a 20 year old car, I don't feel that changing a few inexpensive parts is a bad way to go. Those parts would be due to fail soon and the price to replace them is less than a trip to the shop. With the help of Forum members, I replace the parts that the members think are the problem. I also keep a log book on the service and parts that were replaced.
Thanks, Mickey
Thanks, Mickey
Team Owner
Joined: Jul 2004
Posts: 28,475
Likes: 3,291
From: Hartford WI
I forgot. Is there a chart that shows what resistance it should read at a given temperature? I think I saw one but can't remember the numbers and I don't have my FSM with me. My buddy borrowed it, got kicked out of his house and has a restraining order from his peach of a wife so he can't get it yet.
As to the O2 sensor, what do you look for? I look to see if it has become "lazy" or slow in response.
As to the O2 sensor, what do you look for? I look to see if it has become "lazy" or slow in response.
