New and confused
Thread Starter
7th Gear
Joined: Oct 2014
Posts: 7
Likes: 0
New and confused
Hello all. New to this forum as I am new to corvette ownership. I just picked up a '93 auto with 91k miles as a project/plaything. I've spent the last 5 hours searching thru the tech threads and as soon as I think I've identified the problem, other threads make me think not so much
The problem....was driving and everything seemed fine when suddenly the vette seemed like it was running on 3 cylinders and the rpm's bounced between 500 and 2000 at idle and 1000 and 4000 while limping along at 30 mph. Service engine and info rest lights on. The whole time I babied it home it felt like I was doing brake checks and the engine was clattering. Stalled twice but restarted. Got home turned off and turned on again without cool down and it was fine for idle and revs
ECM? Optispark? Fuel pump? Battery? Thanks guys
The problem....was driving and everything seemed fine when suddenly the vette seemed like it was running on 3 cylinders and the rpm's bounced between 500 and 2000 at idle and 1000 and 4000 while limping along at 30 mph. Service engine and info rest lights on. The whole time I babied it home it felt like I was doing brake checks and the engine was clattering. Stalled twice but restarted. Got home turned off and turned on again without cool down and it was fine for idle and revs
ECM? Optispark? Fuel pump? Battery? Thanks guys
Racer
Joined: May 2012
Posts: 392
Likes: 19
Well, the first thing is to check the codes and see what is going on..........The SES and the info Rest light is on? Do you have a Scanner? FSM? These would be of great help and give a starting point for trouble shooting..
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
The ECM and Opti would be toward the top of the list. but before I went off into left field I would do some checking on the basics. The biggest proem here is that it does seem to correct itself. Really need to know if fuel pressure is good or not. If no gauge, go out and get one if you are keeping the car.
If fuel pressure is good then you can look at other items. The opti usually causes an acceleration problem when throttle is applied. It can cause engine to quit or run rough. Wide variations in RPM is not the norm for opti problems. The ICM surly can cause running problems and that would be ignition related.
On the 93 the ECM is known for a wide variety of problems and symptoms. It runs spark as well as the fuel injectors. Some people have put cold packs on them to see if a change in operation is noted to localize a problem.
These are just suggestions and some background information. Since no real data is known at this time, I cannot really offer an opinion as to what is really wrong and some basic troubleshooting is needed to move forward for a reliable answer. Nothing can be eliminated at this time.
Almost sounds like limp home mode but symptoms sounds worse than it should be if it was.
If fuel pressure is good then you can look at other items. The opti usually causes an acceleration problem when throttle is applied. It can cause engine to quit or run rough. Wide variations in RPM is not the norm for opti problems. The ICM surly can cause running problems and that would be ignition related.
On the 93 the ECM is known for a wide variety of problems and symptoms. It runs spark as well as the fuel injectors. Some people have put cold packs on them to see if a change in operation is noted to localize a problem.
These are just suggestions and some background information. Since no real data is known at this time, I cannot really offer an opinion as to what is really wrong and some basic troubleshooting is needed to move forward for a reliable answer. Nothing can be eliminated at this time.
Almost sounds like limp home mode but symptoms sounds worse than it should be if it was.
Last edited by pcolt94; Oct 19, 2014 at 10:16 PM.
Thread Starter
7th Gear
Joined: Oct 2014
Posts: 7
Likes: 0
Well I have an obd2 scanner which does me no good. I'm looking around for a way to accurately get codes and all I see is using a paperclip to enter a prom read mode and count the number of flashes. Are there scanners for a car that old? Is a '93 obd1 or is that only the 94-95's before obd2 in 96?
Anyway thank you for the response. This is my first ever corvette (had it about two weeks) and this will will definitely be a learning experience. I've worked on cars but always like swapping headers or throttle bodies or window motors. Low tech stuff. Never spark or fuel delivery
Anyway thank you for the response. This is my first ever corvette (had it about two weeks) and this will will definitely be a learning experience. I've worked on cars but always like swapping headers or throttle bodies or window motors. Low tech stuff. Never spark or fuel delivery
Pro
Joined: Aug 2004
Posts: 549
Likes: 13
From: Richmond VA
if you don't like messing with the clips you may want to look at the plugs on this page...
http://www.gordonkillebrew.net/Products
http://www.gordonkillebrew.net/Products
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Verdad Gallardo
Team Owner
Joined: Sep 2003
Posts: 25,394
Likes: 2,741
If your car has C68 (AUTO AC) then I'd see what I could gather from here:
http://tech.corvettecentral.com/2011...trouble-codes/
http://tech.corvettecentral.com/2011...trouble-codes/
Drifting
Joined: Jul 2009
Posts: 1,258
Likes: 98
From: Ashland PA
2021 C4 of the Year - Modified Finalist
your lcd screen that shows your speed will work just like a scan tool. You just need to jump pins A and G and then read this link.
http://tech.corvettecentral.com/2011...trouble-codes/
Hers another link that may help.
http://corvettephotographs.com/c4vettes/codes.htm
http://tech.corvettecentral.com/2011...trouble-codes/
Hers another link that may help.
http://corvettephotographs.com/c4vettes/codes.htm
Last edited by eutu1984; Oct 20, 2014 at 04:06 PM. Reason: add
Advanced
Joined: Aug 2013
Posts: 69
Likes: 0
Amazon has OBD1 scan tools as well. Jumping the pins and reading your dash is not really that big a deal. I'd try that first.
I just went through similar sounding stuff with my 89' and it ultimately ended up being the ECM. I was pleased that it was not all that expensive to replace. For mine, the problem would persist, unless I disconnected the battery and let it sit for a little while. Then, after connecting the battery, it would run just fine for a while.
I just went through similar sounding stuff with my 89' and it ultimately ended up being the ECM. I was pleased that it was not all that expensive to replace. For mine, the problem would persist, unless I disconnected the battery and let it sit for a little while. Then, after connecting the battery, it would run just fine for a while.