CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Sputtering '95 Corvette

I have a '95 'vette LT1 that I bought new for my 50th birthday. I only drive it about 4-500 (yes - hundred) miles a year and for the most part it sits in the garage, gets washed and waxed, and put away. 51000 original miles, the first 40000 put on in the first 1 1/2 years. I’ve had an ignition and fuel injection problem since I bought it. Get’s fixed then some new ignition/injection problemcomes back. Here’s what it does now: car starts fine, runs about 30 seconds with no problem, then starts to miss, runs very rough and very rich (can smell it in the exhaust). After about 3 minutes, the engine smooths out and 2 seconds later, the “check engine” light comes on and the cooling fan starts to run. It runs fine for about 5 minutes, then “check engine” light goes out, fan stops, starts to run rough, misses, gas mileage (per the dash display) goes to about 5 mpg, runs rich, etc. Then the cycle starts again with the “check engine” light and fan coming on and the car running fine. I have no clue. Any ideas?

Whjy ignore what the computer is trying to tell you? It is the single best clue you can get. Step 1: either buy a reader or go have the code(s) read.

I agree with Twin. Get the codes read.

With the fans cooling the car off and it subsequently running better, it sound temperature related but you won’t know until you check the code.
If it is indeed temperature related, you may in fact not want to start it until you know more.

The problem’s root cause IMHO more than likely exists in an erroneous or missing signal from one of the sensors that your ECU uses to determine how much fuel the engine needs. Since it seems so temperature related, I’m guessiing it moght be the temp sensor. The ECU seems unaware that the engine is warming/has warmed up.

Do you have the knowledge and equipment to monitor the temp sensor output as the engine warms up?

I agree with every one that the first thing to do is have the codes pulled from the ECU, but I’m in agreement with @the same mountainbike that it might be the ECT sensor. I was thinking maybe it was sending a false hot temperature causing the cooling fan to come on and inject more fuel to cool an engine the ECU thinks is running too hot.

Good luck getting the codes read on your vehicle. You have the infamous GM non-compliant OBDII engine management system. GM decided to use a system that’s not exactly OBDI or OBDII prior to 96 when OBDII became mandatory. I call it OBDI.V. So this means you can’t retrieve codes using the OBDI method installing a jumper wire in the A & B terminals on the ALDL connector, nor will a regular OBDII code reader/scanner work. To retrieve the codes from your vehicle is going to require either a GM TECH scanner, or an aftermarket scanner with the proper program to pull the codes from your vehicle.

Tester

The procedure described in this link has always worked for me- http://www.neilkline.com/Tech%20Tips/obdcodes.htm