Notices
C4 General Discussion General C4 Corvette Discussion not covered in Tech

Bad plug wires poor acceleration 1994 corvette

Thread Tools
 
Search this Thread
 
Old 06-09-2019, 07:51 AM
  #1  
richardgharris
Racer
Thread Starter
 
richardgharris's Avatar
 
Member Since: Aug 2012
Posts: 284
Received 35 Likes on 20 Posts

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!
Old 06-09-2019, 08:22 AM
  #2  
Paul Workman
Le Mans Master
 
Paul Workman's Avatar
 
Member Since: Oct 2004
Location: South-central Missouri
Posts: 6,314
Received 500 Likes on 395 Posts

Default

Originally Posted by richardgharris
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!!

.



Quick Reply: Bad plug wires poor acceleration 1994 corvette



All times are GMT -4. The time now is 02:20 AM.