poor running
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Joined: Dec 2014
Posts: 74
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From: Lake Butler North Florida
poor running
86 l98 began running poorly a while ago figured it was maf, dt could unhook and would run. Changed with a spectra model maf ran decent for a few days now, on start, idles perfect but has dead spot as soon as on throttle no matter the temp. Stumbles upon gear changes. Anyone have better source for MAF or other suggestions? IAC is in spec and new temp sensor also
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Joined: May 2001
Posts: 4,741
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From: Fairfax Virginia
I would reset both the Throttle Body adjustments and then start looking further. Before any work is done you really should be sure that the fuel pump is priming the systems when the key is first turned to the "Run" position. Next find out your fuel pressure while starting the car. and be sure it is withing the normal parameters for your year Corvette. Low fuel pressure makes a real mess of your idle... Also pull your Fuel Regulators's vacuum line and see if it smells like gasoline, if it does you might have a bad diaphragm in the Fuel pressure Regulator.
My MAF sensor is about 12 years old or so, I have never had "any" issues with the MAF. How old is your O2 sensor? The O2 sensors are supposed to be replaced at every 50 k miles or so and they are frequently forgotten. When they get old and worn out they get "lazy" and take longer to react which would cause all kinds of issues in the "Closed Loop". I forgot to ask, is the car starting up and switching over to the "Closed Loop Mode" as it warms up? MAF sensors don't like air leaking around them. On my 1988 C4 it has the famous "Burn-Off" relay that is supposed to keep the MAF sensor clean. Those circuits have a lot of issues.
How long since you tuned the car up? That might be a good place to start if it has been more than a couple years. Fuel filter, Distributor Cap and Rotor, new Spark Plug wires, Spark Plugs. You might just have a bad O2 sensor that has not completely failed yet. You can check it's output voltage and see if it is in the proper range. How old is the gasoline in the tank? Your car might just need a good can of B&G 44K Fuel Injection cleaner to get it running smoothly again.
Some good old basic maintenance will get your car running smoother I suspect. Let us know as we want to help you find a solution that works. Good Luck!
My MAF sensor is about 12 years old or so, I have never had "any" issues with the MAF. How old is your O2 sensor? The O2 sensors are supposed to be replaced at every 50 k miles or so and they are frequently forgotten. When they get old and worn out they get "lazy" and take longer to react which would cause all kinds of issues in the "Closed Loop". I forgot to ask, is the car starting up and switching over to the "Closed Loop Mode" as it warms up? MAF sensors don't like air leaking around them. On my 1988 C4 it has the famous "Burn-Off" relay that is supposed to keep the MAF sensor clean. Those circuits have a lot of issues.
How long since you tuned the car up? That might be a good place to start if it has been more than a couple years. Fuel filter, Distributor Cap and Rotor, new Spark Plug wires, Spark Plugs. You might just have a bad O2 sensor that has not completely failed yet. You can check it's output voltage and see if it is in the proper range. How old is the gasoline in the tank? Your car might just need a good can of B&G 44K Fuel Injection cleaner to get it running smoothly again.
Some good old basic maintenance will get your car running smoother I suspect. Let us know as we want to help you find a solution that works. Good Luck!
