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Bad plug wires poor acceleration 1994 corvette

 
Old 06-09-2019, 07:51 AM
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richardgharris
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Default Bad plug wires poor acceleration 1994 corvette

I have been chasing this problem for awhile as some of you may know from my other posts. The problem is poor acceleration, pinking, knocking etc.on a 1994 corvette base LT1. It does not start right away when cold only after a few minutes of running. When I changed the plugs I noticed that number one cylinder plug was black, not ash like all the others. Did not dwell on it and replaced all the plugs with no change in performance. Code H 64 keeps showing up and it runs like crap in closed loop.

Last night I went out to the garage starting the engine and standing over the motor while it was running in the dark. I noticed a spark shoot from the number one or two spark plug wire to the heat shield on the manifold. I accelerated the engine and it got much worse. I went to all the receipts and found out that the opti, coil, IMC was replaced but no were did I see that the spark plug wires were replaced. I have ordered new ones but while I wait for them to arrive I have a theory and I am looking for your opinion?

If number one is misfiring badly on acceleration would the O2 sensor pick up a code H64 and cause the computer to change the fuel mixture after warm up? It runs good cold but after it goes to closed loop it runs terrible. The change in fuel mixture combined with the misfire on number one or two or both would make the car run like crap on acceleration, is this a possibility? As always thank you for your opinions!
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Old 06-09-2019, 08:22 AM
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Paul Workman
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Originally Posted by richardgharris View Post
I have been chasing this problem for awhile as some of you may know from my other posts. The problem is poor acceleration, pinking, knocking etc.on a 1994 corvette base LT1. It does not start right away when cold only after a few minutes of running. When I changed the plugs I noticed that number one cylinder plug was black, not ash like all the others. Did not dwell on it and replaced all the plugs with no change in performance. Code H 64 keeps showing up and it runs like crap in closed loop.

Last night I went out to the garage starting the engine and standing over the motor while it was running in the dark. I noticed a spark shoot from the number one or two spark plug wire to the heat shield on the manifold. I accelerated the engine and it got much worse. I went to all the receipts and found out that the opti, coil, IMC was replaced but no were did I see that the spark plug wires were replaced. I have ordered new ones but while I wait for them to arrive I have a theory and I am looking for your opinion?

If number one is misfiring badly on acceleration would the O2 sensor pick up a code H64 and cause the computer to change the fuel mixture after warm up? It runs good cold but after it goes to closed loop it runs terrible. The change in fuel mixture combined with the misfire on number one or two or both would make the car run like crap on acceleration, is this a possibility? As always thank you for your opinions!
It certainly may result (cause and effect) in erroneous AF readings. But, the best way to look at it is with a scanner so you can see ALL of the activity. For example, I experienced an O2 sensor that intermittently would short out and thus report a LEAN condition to the ECM. In response, the injector dwell time was increased and the engine ran (sort of) extremely RICH on one side in (as you pointed out) CLOSED LOOP.

Well, if replacing the known bad wires fixes the problem, then we have another "cause and effect" example. Your poor running issue may well end with the new wires, me thinks!!

.
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