Folks,

My daughter'* grandma car had a check engine light since I bought it at an auction. It had a code 34, but ran fine so since the sensor was so darned expensive, she just kept running it. On several trips, she has some major power loss issues, but was always able to limp home. About a month ago, it didn't have enough power to get out of the driveway, so there it sits. I convinced her to buy an aftermarket sensor for big $$ (for a student anyway). Now the car will not run unless I manually open the throttle while she starts, and then it will idle OK but die immediately under load,even with this new sensor on it. And the ECM is still throwing a code 34 at us.

I bought and replaced the connection pigtail, thinking maybe it was bad.....no help.

I have checked for vacuum leaks and have found none, any suggestions where I might concentrate my search?

I have checked the circuit diagram and don't see a relay; only a connection to PCM (yellow wire) and Fuse panel (pink/black), and of course ground (black).

WHAT AM I MISSING?

first off welcome to the forum it would help greatly ifwe knew what year make and model and trim this vehicle is..i would test Fuel pressure first and foremost..sounds similar to symptoms of bubba when his fuel pump died

Sorry. Buick Century Custom 1989 3.3 liter. Fuel pressure checked out. It seems when I do get it running that it is running extremely rich.

have you tested coil voltage

Code 34 is your MAP sensor, not your MAF, big difference. With a bad MAP the car will run very badly, no power, may not shift right, incorrect AFR. Also easy to change, and far less expensive then a MAF.

I am not so sure this car has a MAP sensor. Aren't MAP sensors on throttle body injected machines?

I will test the coil voltage as suggested.

RockAuto says your engine has one ( http://www.rockauto.com ) Always best to first attack what the cars computer is telling you the "fault" is.

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well, my code reader not only gives the code, it spells out the fault, and it clearly says MAF or MAF circuit problem. Please don't be condescending...it is not helpful. I have been around cars; just new to this forum. The Haynes manual for this car doesn't show a MAP sensor in the wire diagram for engine controls, nor in the location photos of various emissions/engine controls. A MAP is shown for 2.2, 2.8, and 3.1'* but not for the 3.3. So based on your advice, I checked the engine compartment over very carefully. I traced each vacuum line coming from the manifold area,and cannot find a sensor that has both wires and a vacuum line attached. If there is a MAP sensor, I have not found it.

Didn't mean it to sound condescending. I just checked with Rockauto whose database I've used alot and found it pretty faithful. And the statement about trusting the cars computer was pointed at another poster who'* advice steps around that. I'll look into it here a bit more.