C4 Running too rich



C4 Running too rich

Postby c4 Travis » August 16th, 2013, 11:58 am

My 1985 C4 runs super rich since ive had it for a few months now. I'm kinda new to working on it so I've basically thrown everything but the kitchen sink at it with a tune up and new fuel system components. I just put in a new fuel pressure regulator because I had fuel in my oil and thought that might be the culprit. SInce I've added the new regulator and an oil change, it still runs rich and falls flat on it's face on WOT. I have not yet tested or replaced my O2 sensors, is this the next logical step? Am I missing something simple here?

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Re: C4 Running too rich

Postby grumpyvette » August 16th, 2013, 12:01 pm

yes it sounds a good deal like a defective o2 sensor problem,or a MAF, or heat sensor issue, but pull trouble codes and run a few tests, example, if its a leaking injector causing the issue it could have easily fouled the o2 sensor to the point it won,t read correctly but it would more than likely also cause the catalytic converter to partly clog if it was running rich for more than a few weeks time!
Image
viewtopic.php?f=50&t=9478&p=34812&hilit=sensor#p34812

viewtopic.php?f=32&t=8743&p=30904&hilit=sensor#p30904

viewtopic.php?f=32&t=2697&p=29270&hilit=sensor#p29270

viewtopic.php?f=70&t=7309&p=24862&hilit=sensors#p24862

viewtopic.php?f=80&t=728&p=8392&hilit=sensor+location#p8392

http://members.shaw.ca/corvette86/FuelS ... gnosis.pdf

http://www.thirdgen.org/tpimod2
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: C4 Running too rich

Postby c4 Travis » August 16th, 2013, 12:05 pm

The only codes I'm showing are

22-TPS low voltage
54-Fuel pump circuit fault/fuel pump relay

I replaced the TPS, Fuel pump relay, fuel pump, and oil pressure witch in that circuit. I cant figure out for the life of me why those won't clear.
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Re: C4 Running too rich

Postby grumpyvette » August 16th, 2013, 12:10 pm

viewtopic.php?f=32&t=168

start by reading thru the posted links above, buying a shop manual for that 1985 corvette and getting a multi meter and timing light and vacume gauge, then setting the IAC and TPS and ignition timing and checking the fuel pressure stays at 38-40 psi for at least 5 minutes after the engines shut off to verify the FPR and injectors don,t leak
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: C4 Running too rich

Postby 87vette81big » August 16th, 2013, 12:21 pm

The TPS & MAF Are MAIN SENSOR INPUTS on all 1985-89 TPI cars.
Grumpy has Great Links always.
Take time to read them.
Must make sure you have 5 volts DC reference at TPS & MAF.
A Ground wire connection at both sensors too.
Ground must resistance check 1 ohm less referenced back to the negative battery cable.

There is a guy in Los Angelous California that sells used original GM Corvette Service manuals at a fair price. On Fleabay Ebay. $30 worth it.
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