85 Needs Help
Thread Starter
Instructor
Joined: Nov 2011
Posts: 105
Likes: 0
From: Nashville TN
85 Needs Help
Now that My ZR1 is fixed (thanks to all the guys on that thread), I'm having my 85 looked at by a local "Vette Shop" that was recommended by a fellow club member. It would run OK when driven lightly in normal traffic but when I push the pedal down, it appears to be down a cylinder or two. This shop has had the car since before Thanksgiving and cant seem to find the problem. They have ruled out injectors and supposedly checked everything they could. One thing they did suspect was a stuck EGR valve. They found the EGR stuck open and fabricated a "plate" to seal off the valve. After that, they said it ran better but still not right. My confidence is fading and my bill is rising. They told me that one of my catalytic convertors was "cherry red" and that could also be part of the problem. The problem came on gradually over 2-3 months and got worse
When another local shop looked at it previously, they said it ran OK in closed loop and had problems in open loop ?!?!.
When another local shop looked at it previously, they said it ran OK in closed loop and had problems in open loop ?!?!.
Instructor
Joined: Sep 2011
Posts: 131
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From: Illinois
I had a similar problem, once the car was warmed up and a load was applied to the engine I would lose a cylinder. It ended up that putting a heavy load on the motor was making the spark plug arc to the head through the plug boot. They were cheap ones the PO put on. I swapped them out with some new MSD ones and it solved the problem. Just something to check, I discovered it cause I had the hood open one night with the engine running, e brake on, and in drive and let it sit and warm up. Saw and herd the arching easily standing over the motor. There are also test lights too that check to see if its grounding to something other than the spark plug.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
I had the same exact symptoms. OK when cold. Miss when hot.
Turned out to be a bad #6 spark plug wire. It had opened near the spark plug and was arcing to the dipstick tube. Found it by looking at the running engine in a dark garage.
Seems like an echo of what BroCorvette said...
Turned out to be a bad #6 spark plug wire. It had opened near the spark plug and was arcing to the dipstick tube. Found it by looking at the running engine in a dark garage.
Seems like an echo of what BroCorvette said...
Thread Starter
Instructor
Joined: Nov 2011
Posts: 105
Likes: 0
From: Nashville TN
It turns out that they found a fouled #1 plug was the final culprit. I am curious how the cherry red convertor is no longer a problem. I'll ask when I pick the car up later today and pay the bill for new injectors, a faulty EGR valve and also an ignition module. I have to say though that considering the time they probably have in in it, the bill wasn't too bad.
Thanks!
Thanks!
Thread Starter
Instructor
Joined: Nov 2011
Posts: 105
Likes: 0
From: Nashville TN
The saga continues. Twice I was told by the shop it was ready and repaired, both times it ran good for only a matter of hours....
We have replaced, plugs, wires, coil, injectors, sealed off EGR (thought to be leaking)....verified data from sensors, per the mechanic, all seem to be responding.
It will run for a few blocks or a few miles fine then stumble like losing a cylinder or two....
It runs fine under light or moderate throttle but push the pedal to the floor and about 1/2 the time, it craps out. Almost sounds like a bad or loose connection or something. Was told by another mechanic that attempted to repair that it seemed to run OK in open loop and poorly in closed.
We have replaced, plugs, wires, coil, injectors, sealed off EGR (thought to be leaking)....verified data from sensors, per the mechanic, all seem to be responding.
It will run for a few blocks or a few miles fine then stumble like losing a cylinder or two....
It runs fine under light or moderate throttle but push the pedal to the floor and about 1/2 the time, it craps out. Almost sounds like a bad or loose connection or something. Was told by another mechanic that attempted to repair that it seemed to run OK in open loop and poorly in closed.
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Le Mans Master
Joined: Aug 2010
Posts: 9,272
Likes: 17
find another shop, you've donated way to much to that ones christmas party. find one that will do a diagnostic...'before' ...replacing parts, find one that specializes in tuneup's and electrical, the 'one' of your converters glows red should be a clue. some thing else you could do is say what your location is. just in this forum there are a multitude of 'real' mechanics spread around the country and one of them may be able to refer you to a real shop in your area..hope this helps
Last edited by oldalaskaman; Dec 22, 2011 at 01:24 PM.
Thread Starter
Instructor
Joined: Nov 2011
Posts: 105
Likes: 0
From: Nashville TN
Agreed but at this point he is assisting with no additional charge. He wont get another dime from me. Believe it or not, this is my third attempt locating a mechanic to resolve this problem. It's amazing how many times i hear "Oh sure, I'm familiar with an 85 vette, we can fix it..."
He did verify fuel pressure was good under load and also the fuel filter`was replaced.
He did verify fuel pressure was good under load and also the fuel filter`was replaced.
theres some good mechanics in that area, others will chime in , I'm sure
Le Mans Master
Joined: Aug 2010
Posts: 9,272
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http://forums.corvetteforum.com/southeast/1101039-vette-shops-in-n-e-tennessee.html?highlight=mechanic+tennes see..........http://forums.corvetteforum.com/southeast/2783804-need-help-in-east-tenn-to-rekindle-the-fire.html?highlight=good+mechanic....... http://forums.corvetteforum.com/southeast/2283827-shop-mechanic-tn.html?highlight=good+mechanic.....:roc k:.http://forums.corvetteforum.com/southeast/1664606-c-4-or-vette-mechanic-nashville-area.html?highlight=good+mechanic....... http://forums.corvetteforum.com/southeast/1639050-looking-for-a-great-mechanic-in-the-nashville-area.html?highlight=good+mechanic....... http://forums.corvetteforum.com/southeast/1370887-looking-for-good-mechanic-in-nashville-tn.html?highlight=good+mechanic.......:r ock:http://forums.corvetteforum.com/southeast/874093-mcv-mechanic.html?highlight=good+mechanic... ........I got these just doin a search for 'mechanic' in the southeast section, there's some redundency, hope it helps
Last edited by oldalaskaman; Dec 22, 2011 at 08:45 PM.
Le Mans Master
Joined: Aug 2010
Posts: 9,272
Likes: 17