C4 Corvette

The governor on the transmission is connected to the engine via a vacuum hose. If the governor fails the engine could draw transmission fluid into the combustion chamber causing a misfire. It should also be visible in the engine oil as without doubt some of it would wash past the rings into the sump.
Saw this exact thing on a V6 Granada a few years ago. Weirdly there was no smoke when running but the engine sump was filling up with good old dexron and the combustion chambers were immaculately clean!

I doubt this is your problem but it's an easy check.
 
Checked fluid level in auto box. As it should be and no dis-colouration. I will try EGR valve next. Also need to take out digital dash to see if ALDL is hiding in there somewhere.
 
That's good news. Now, is your EGR vacuum operated or one of electronic ones? Either way disconnect it remembering to plug the vacuum line to avoid a vacuum leak and try again.
An electronic one might set a code and the SES lamp on its own but you can still
Drive it to see if you get a misfire.
 
I have checked the auto box fluid level and it is as it should . Colour is good. I have really been stuck for time. I manage a big band for my sins, and the guy whose band it is has been diagnosed with Dementia .His remaining family live in Scotland and he has no friends to speak of, so , I am his temporary carer until proper care is in place. Fed up with filling in forms for him and hospital appointments. There is a tiny light at the end of the tunnel which I hope will get bigger quickly. Cosworth has only been out once since last September. and Corvette hasn't been touched for a month or more. Roll on next spring, if I am not in need of care myself!!!!!.
 
John B said:
and the guy whose band it is has been diagnosed with Dementia .His remaining family live in Scotland and he has no friends to speak of, so , I am his temporary carer until proper care is in place. Fed up with filling in forms for him and hospital appointments. There is a tiny light at the end of the tunnel which I hope will get bigger quickly.
Click to expand...

I know what you mean, there is a lot of paperwork. It is a difficult one. Hope all goes well and that care will be sorted shortly.
 
Hi guys, my situation is still much the same with the old guy I am helping. I did strip out the digital dash to try and locate the ALDL. Still no luck. I have stripped out the panels under the dash and still can't find it. Is it possible to read the fault codes elsewhere in the wiring harness?. Is there a mechanic out there who could sort the problem for me?. I would be willing to pay to get this bloody car sorted and running again. I am away from the 24th September probably for a couple of weeks. If someone could sort, they would need to come to my house in Waterlooville as I don't think the car would run any distance.
 
Have you checked under the center console ashtray? Some models had the ALDL connection there and not above the drivers right knee.
 
I wouldn't know where to start on a C4, the only guy i know is Dennis Tomlinson, he has a C4, and owned it for many years, he has also fixed many cars over the years. Next time I see him I'll have a word, and try to get his phone number.
 
The TPI's are very straight forward. Approaching it logically will probably resolve the issue but what's making this one difficult to diagnose is the length of time between the updates. I'm not sure what's been checked and what hasn't.
Unfortunately that's the difficulty with the extremely remote diagnosis and whatever time John is able to Devote to it.
Nobody's fault , just tough to do. John is right, it would be easier for someone to go to him. I wish I could help but distance and time are not on my side either! Happy to continue to make suggestions though.
 
AmericanThunder said:
Have you checked under the center console ashtray? Some models had the ALDL connection there and not above the drivers right knee.
Click to expand...
That is worth a look!!! The ALDI is not above the drivers Knee. I find it hard to believe that it has been removed as that would be more trouble than it is worth to do with little point in doing it. I will have a look. Thanks.
 
Hi Guys, hope all is good with you all. At last, had some time to have a go at the C 4 Corvette. Actually found the ALCL connector hidden behind the radio. Prior to finding it, I used some Halfords electrical cleaner to clean the MAF sensor. The car ran better after this but Service engine soon light came on after 10 minutes ticking over in my drive .After finding the ALCL link, I disconnected the battery for 10 minutes or so to reset the ECU. After reconnecting, I ran the car for around 5 minutes and then turned it off. I then bridged terminals A and B to check any stored fault codes. Code 12 flashed 3 times and then repeated which means no stored codes. Next move is to take the car out and see if( service engine soon) light comes on again with associated bad misfiring as before. I hope the problem is resolved. Will post again after running car on the road.
 
Cant beat a good test run :biggrin1:
 
Thats great news, hopefully the fault has cleared and stays away. At least you know where the connector is now to read out any future codes.
 
Took the C4 out today. Did about 10 miles and it did not miss a beat, and (service engine soon ) stayed off. I stopped to admire our new carrier and have a cup of tea. About 20 minutes later, I headed for home and as I passed Fort Widley, Service engine soon light came back on and the car started to misfire and instant fuel reading dropped from plus 20 mpg down 8 or 9 mpg. It was possible to accelerate and the mpg figure returned to over 20 mpg. I drove home and went to the fault code procedure. It came up with 12 which means no fault codes stored in ECU. I took the car out again and drove at 70 mph up the A3M I turned around at the Hogs Lodge and drove back down the A3M. The service engine light came on again . Loss of power, misfires, and MPG back to single figures. I accelerated out of the misfires and as before the MPG rose to plus 20 but light stayed on. It seems that the engine is over fuelling at low revs(up to 2000 rpm) . It seems strange that when the ignition is switched off and then on again, the service engine soon light goes off and stays off for a period of time and the fault does not rear its head. I am beginning to suspect that the MAF sensor is possibly at fault. Any thoughts any-one?.
 
Last edited:
When you were driving down the A3M and the SES light came on, what were you doing?
Accelerating, braking or just cruising?
 
Hi All. C4 problems sorted at last. I found the test block behind the radio, but it did not throw up any fault codes. After a lot of deliberation, I came to the conclusion that it was either the ECM or MAF. As Keith at Eurovettes had an ECM in stock, I gave that a try. Got C& S garage to fit it and it seems to have done the trick. Car ran well on test drive and did not miss a beat. Next job, stop water getting in around the removable roof.
 
Glad to hear the good news that you finally got it sorted at last.
 
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