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1994 performance problem

 
Old 04-11-2019, 09:14 PM
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richardgharris
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Default 1994 performance problem

I have been working on a 1994 base coupe with a performance problem. It runs well in closed loop but pings and backfires once it get into closed loop. I have replace the TPS sensor and both O2 sensors, code 64 showed up and than code 42. I put new gas in the tank and added sea foam to the gas. The car runs noticeably better and seems to improve as I put miles on. I get no coeds presently. I am hoping the computer takes time to reset. I have to take a break to replace a leaking heater core and power antenna mast. I just rebuilt the head lights motors. I bought this car to tinker on in retirement. It has great paint, good interior, good tires. The big things have been replaced before I purchased the car. The opti spark, water pump, fuel pump, fuel filter and the main computer have been replaced. I also think the injectors were replaced as well.

My question is...... The car runs much better but not 100%. Could it get better with miles? If it does not what should I look to replace next?

My final comment is to thank all the folks that respond to this forum. With your help I have fixed many corvettes over the
Years!!
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Old 04-12-2019, 08:16 AM
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TorchTarga94
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Check the fuel pressure reading and the fuel pressure regulator.

Last edited by TorchTarga94; 04-12-2019 at 08:17 AM.
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Old 04-12-2019, 08:45 AM
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3D-Aircrew
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Originally Posted by richardgharris View Post

My final comment is to thank all the folks that respond to this forum. With your help I have fixed many corvettes over the
Years!!
Have you always been richardgharris?

FPR is an easy check ... if there is fuel in the vacuum line to it then it has a bad diaphragm.

Are wires and plugs OK?
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Old 04-12-2019, 08:27 PM
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richardgharris
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Fuel pressure readings are fine and the fuel pressure regulator shows no signs of failure.
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Old 04-12-2019, 08:28 PM
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richardgharris
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I am not sure about wires and plugs? I may look there next, Thank you!
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Old 04-13-2019, 12:28 AM
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Good luck with the heater core replacement. I recently did mine. Get lots of baggies for bolts and take lots of pictures. Almost everything has to come out do to it right.

I wouldn't expect the running to improve much more. All the computer is calculating and storing is your sort and long term fuel trims. Are you able to watch the sensor readings live?

What are the temps running when its pinging and backfiring, just after entering closed loop?

I would use something like EEHack to record some drives and see if you can pickup any need for a tune. I would also use a professional injector cleaner because it never hurts to clean a 25 yr old car's injectors.
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