SAGA continues, ANY suggestions welcomed
09-01-2013, 01:24 PM
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SAGA continues, ANY suggestions welcomed I am at a complete and utter loss. I will apologize up front for the length of the post. I want to give the details in the hope that it might strike a note with someone. The car is a '94 corvette.
1st Repair: the engine had oil leaks and one of them totally saturated the Optispark. I mean completely. The car was acting like it was flooding when you drove at a set speed for a few minutes and then got on it hard or progressively but quickly. It was like a carbed car flooding out but without the burnt gas smell. I'm in GA and the car was in NC about 300 mi away. The shop changed the plugs, new Magnacor plug wires, coil, Throttle Pos. Switch, water pump and installed a new MSD Opti.
It drove fine all the way home ~300mi. The only odd thing was that it would take 4-8 tries to start. It used to always start up just touching it once and almost immediately. They told me it was the ECM learning the new "inputs" from the MSD unit. When trying to start it would just turn over with no attempt to start. Like either fuel or spark were just not there. When it did start there was no rush of rich exhaust gas.
Anyway, for 300 miles it was fine. The next day I got up and went to work and after driving maybe 15 miles (during which it ran perfectly) it started doing the SAME thing as before. Drove fine but when getting on the gas after a set speed, it would act like it was flooding out! It did the same thing on my 35 mile drive home later that day.
2nd Repair: The next day I drove it to a local shop whose work is 90%+ Chevy V8s (much of it performance work) and on the way there the car began surging hard. Almost like you were accelerating pretty hard and then hit the brakes. If I wasn't about 6 mi from the shop I would have just gotten a flatbed. It would come and go at random and when it went, the car ran fine. It has never done this before. I tried to do my homework in selecting the 2nd shop. I asked people in the local vette club. 4 of 5 said the same shop. I then asked a well known LS engine place if THEY had an LT1 where would they go with it. They said the same place as the other 4 in the vette club.
This 2nd shop diagnosed the MSD Opti as defective of all things! The problem then became that MSD said the Opti was back ordered for at least 30 days! Since I'm in GA I got to Summit Racing and they recommended their unit which I believe is made by Accel. Anyway, the 2nd shop installs yet another new Opti and finds 2 air leaks in the intake manifold so a new gasket was installed. They also checked the engine control unit which was functioning properly and installed new plugs again because the old ones with just ~300 miles were ran WAY rich. The EGR was also changed.
Now the weird part. They called last Monday ago and said the car was ready. Not wanting any issues, we asked them to keep it a few days and drive it as much as they wanted. They drove it hooked to a laptop and verified the fuel pressure was fine and all seemed good. Friday I got the all clear. We went to pick it up and I left with a HUGE smile, drove 12.1 miles and it bucked. Then cleared up and at 15.4 miles it began bucking hard again. Just like before!!! I was so upset!!! I turned around and on the way back to the shop when it seemed to clear up, got on it 4 times progressively but not just bam WOT. Each time the car just fell flat on its face like before making that awful baaaaaaaaaaaaaa sound.
Now it's back at the 2nd shop. WHAT THE HECK?! Any opinions? I'm still thinking it's a fuel pressure problem.
Ron B.
1st Repair: the engine had oil leaks and one of them totally saturated the Optispark. I mean completely. The car was acting like it was flooding when you drove at a set speed for a few minutes and then got on it hard or progressively but quickly. It was like a carbed car flooding out but without the burnt gas smell. I'm in GA and the car was in NC about 300 mi away. The shop changed the plugs, new Magnacor plug wires, coil, Throttle Pos. Switch, water pump and installed a new MSD Opti.
It drove fine all the way home ~300mi. The only odd thing was that it would take 4-8 tries to start. It used to always start up just touching it once and almost immediately. They told me it was the ECM learning the new "inputs" from the MSD unit. When trying to start it would just turn over with no attempt to start. Like either fuel or spark were just not there. When it did start there was no rush of rich exhaust gas.
Anyway, for 300 miles it was fine. The next day I got up and went to work and after driving maybe 15 miles (during which it ran perfectly) it started doing the SAME thing as before. Drove fine but when getting on the gas after a set speed, it would act like it was flooding out! It did the same thing on my 35 mile drive home later that day.
2nd Repair: The next day I drove it to a local shop whose work is 90%+ Chevy V8s (much of it performance work) and on the way there the car began surging hard. Almost like you were accelerating pretty hard and then hit the brakes. If I wasn't about 6 mi from the shop I would have just gotten a flatbed. It would come and go at random and when it went, the car ran fine. It has never done this before. I tried to do my homework in selecting the 2nd shop. I asked people in the local vette club. 4 of 5 said the same shop. I then asked a well known LS engine place if THEY had an LT1 where would they go with it. They said the same place as the other 4 in the vette club.
This 2nd shop diagnosed the MSD Opti as defective of all things! The problem then became that MSD said the Opti was back ordered for at least 30 days! Since I'm in GA I got to Summit Racing and they recommended their unit which I believe is made by Accel. Anyway, the 2nd shop installs yet another new Opti and finds 2 air leaks in the intake manifold so a new gasket was installed. They also checked the engine control unit which was functioning properly and installed new plugs again because the old ones with just ~300 miles were ran WAY rich. The EGR was also changed.
Now the weird part. They called last Monday ago and said the car was ready. Not wanting any issues, we asked them to keep it a few days and drive it as much as they wanted. They drove it hooked to a laptop and verified the fuel pressure was fine and all seemed good. Friday I got the all clear. We went to pick it up and I left with a HUGE smile, drove 12.1 miles and it bucked. Then cleared up and at 15.4 miles it began bucking hard again. Just like before!!! I was so upset!!! I turned around and on the way back to the shop when it seemed to clear up, got on it 4 times progressively but not just bam WOT. Each time the car just fell flat on its face like before making that awful baaaaaaaaaaaaaa sound.
Now it's back at the 2nd shop. WHAT THE HECK?! Any opinions? I'm still thinking it's a fuel pressure problem.
Ron B.
09-01-2013, 05:26 PM
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The 2nd shop has the car so I don't know if there are any codes to download. Having paid for 2 Optisparks AND installation in less than 500 miles there's no way I'm paying to install a 3rd, GM component or not.
The O2 sensor(s ) tested out fine. I had asked the 1st shop to change them since the car is relatively new to me and I don't know when they were last done. But the shop said it tested fine. The 2nd shop said the same thing so it shouldn't be the O2.
I was just fishing for some hope that someone out there had the same issue.
The O2 sensor(s ) tested out fine. I had asked the 1st shop to change them since the car is relatively new to me and I don't know when they were last done. But the shop said it tested fine. The 2nd shop said the same thing so it shouldn't be the O2.
I was just fishing for some hope that someone out there had the same issue.
09-01-2013, 06:12 PM
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When It does this bucking you need to put a fuel pressure gauge on it. It's no good to have data logs and test equipment on it when it is running fine. Pick up a fuel pressure gauge and run with that thing on there for like a week so you can read it while driving.
Could be the pump going or it could even be a bad regulator. Another thing to check is the injector plugs. Sounds odd but my first car I ever had was an 83 starion turbo. It would do this odd bucking randomly and run way rich and then act like the key had been turned off. Years went by with money flying out of my wallet. No shop could figure out why it did this and it turned out that it had bad injector plugs. Check all the grounds for the engine electrical and make sure they have clean contact and also check the connectors to make sure they have a clean connection to the different components.
Hate to break the news to you but it could also be the opti. I had a summit unit and it failed after 3k miles.
Could be the pump going or it could even be a bad regulator. Another thing to check is the injector plugs. Sounds odd but my first car I ever had was an 83 starion turbo. It would do this odd bucking randomly and run way rich and then act like the key had been turned off. Years went by with money flying out of my wallet. No shop could figure out why it did this and it turned out that it had bad injector plugs. Check all the grounds for the engine electrical and make sure they have clean contact and also check the connectors to make sure they have a clean connection to the different components.
Hate to break the news to you but it could also be the opti. I had a summit unit and it failed after 3k miles.
09-02-2013, 08:47 AM
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The coil was changed too. Sorry I forgot to mention that. The mechanic called yesterday and said the ignition control module was melted. Greta that a problem has been found but I doubt that alone would cause my problems. The guy feels terrible that he said it was fixed, drive it well over 100 miles and then I got it for less than 20 miles. It's still odd that he drove it that many miles and encountered no issues.
