92 Chevy Silverado 1500 running rich, and idling up and down
Have changed spark plugs, and dist cap
On computer only code was for MAP sensor
throttle body gasket
and it's still running rich, can smell gas in the exhaust and mileage SUCKS.
what to look at next??? Any ideas?
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Did you try another MAP sensor ...? You said your code was for the MAP. That sensor can cause haywire if it doesn't work right.
Personally, I'd go to Autozone and buy a sensor, but DO NOT SCREW IT IN! If the sensor does not fix your problem, then they wont take it back if it looks like you installed it. You can connect the sensor and plug it in without having it screwed down. That way you can test with it.
I've got new injectors coming. The map sensor has been disconnected, my mechanic says that sometimes with the MAP sensor it's the best thing to do.
YES..... It's blowing black smoke that smells like gas.
The fuel pressure regulator will be the next ry if the new injectors don't fix the problem. THANKS EVERYONE!
Well I can't speak for a '92 truck, but on my own '89 Silverado 5.0L engine, unplugging my MAP only made matters worse. Much worse. Wouldn't idle at all, didn't have any power.
Print this out and have your mechanic test your MAP, or do this yourself. It is VERY important to use a good multimeter/volt meter for this, or risk trashing ECM - DO NOT USE A TEST LIGHT.
Backprobe with a high impedance voltmeter at MAP sensor terminals A and C.
With the key ON and engine off, the voltmeter reading should beapproximately 5.0 volts.
If the voltage is not as specified, either the wiring to the MAP sensor or the ECM may be faulty. Correct any wiring or ECM faults before continuing test.
Backprobe with a high impedance voltmeter at MAP sensor terminals B and A.
Verify that the sensor voltage is approximately 0.5 volts with the engine not running.
Start the vehicle.
Verify that the sensor voltage is greater than 1.5 volts at idle.
Verify that the sensor voltage increases to approximately 4.5. volts at Wide Open Throttle (WOT).
If the sensor voltage is as specified, the sensor is functioning properly.
If the sensor voltage is not as specified, check the sensor and the sensor vacuum source for a leak or a restriction. If no leaks or restrictions are found, the sensor may be defective and should be replaced.
I'm still worried about that code for the MAP. Do you remember/know what number the code was? Definitely replace the FPR though. I'm not saying anybody else's suggestions are wrong, but your MAP code could likely be causing issues - like the sensor telling the computer that you're at WOT - which would in turn make your fuel trim go super rich to keep the engine alive at high RPM.
Just thoughts. Doesn't make 'em correct, but testing the MAP is easy as long as you're: A) Careful, B) using good equipment. You can always print that off and have your mechanic do it.
PS: I used my snap-on multimeter for this job this week. I was scared of roasting my ECU. DO NOT SHORT THE PINS.
I'd like to thank everyone for the suggestions.
After changing the injectors yesterday she's running great again!!
Mechanic just got a new snap on program and will be hooking her up for free to see how she reads now.