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Maf Sensor Problem?

by alvin, June 28, 2007



My 2001 Corolla ( 150K) is having some problem.

It is starting fine, but as soon I put the car in "D" , it doesn't move unless i press the gas hard enough.

sometimes it even stops running if not given enough gas.

doesn't give any problem when on the road.

the mechanic says i need to change my MAF sensor, but for some reason i am not buying it.

any idea what the problem might be.

I searched the net and found some Volvo having this Engine Idling problem, is this the same thing.

Please note, the Car runs fine otherwise.

thanks for your help

Need a bit more info -

Does the car idle fine in park and neutral?

How does it run when in reverse?

Can you rev the engine in park and neutral and it still runs OK?

What happens if you turn on the A/C in park or neutral - does the engine idle speed jump up a little?

Did you check the transmission fluid recently?

Are the levels for the fluid fine?

You are correct to be suspicious - the car would not idle at all if the MAF was bad, in any gear. That said, it could just be that the IAT sensor and MAF sensor (they are mounted together in a module in the airbox)could just be dirty - more so if you notice any performance drop. The Idle Air valve seems a more likely suspect, assuming that the transmission is fine. Idle Air valve is on the throttle body and makes sure that the idle changes with increase in engine load. Could also be any number of sensor issues - could even be a transmission issue (clutch bands inside or a something wrong with the valvebody).

Thanks fishexpo101 !!

really appreciate your input.

The first time this happened, i thought it was a transmission problem and i believed the same till the date the Mechanic said otherwise.

to answer your questions:

1) Yes, the car idles just fine in P and N, no issues there. I let it run for couple of minutes and did not see any problem at all, the engine runs pretty smooth.

2) I don't remember any problem in Reverse either

3) The Engine REVS just fine in both N and P, no issue there, either.

4) Yes, When I turn the AC on, the engine idle speed jumps up a little, but i guess that's normal, right?

5) I took the car to the mechanic and he checked all the Fluide Levels and topped it off, at least that's what he said.

I checked the Fluid level (except transmission) my self and they all look good to me too.

The car had it's transmission Service done (fluid change etc) in March 2006 @ 120K.

do you think it's about time i get the transmission service done again?

Thanks again and really appreciate your feedback.

-al

Need a bit more info -

Does the car idle fine in park and neutral?

How does it run when in reverse?

Can you rev the engine in park and neutral and it still runs OK?

What happens if you turn on the A/C in park or neutral - does the engine idle speed jump up a little?

Did you check the transmission fluid recently?

Are the levels for the fluid fine?

You are correct to be suspicious - the car would not idle at all if the MAF was bad, in any gear. That said, it could just be that the IAT sensor and MAF sensor (they are mounted together in a module in the airbox)could just be dirty - more so if you notice any performance drop. The Idle Air valve seems a more likely suspect, assuming that the transmission is fine. Idle Air valve is on the throttle body and makes sure that the idle changes with increase in engine load. Could also be any number of sensor issues - could even be a transmission issue (clutch bands inside or a something wrong with the valvebody).

From my experience, if either the transmission or the torque converter are bad, no service will bring it back, unless it really is just low on fluid.

Does the check engine light come on at all? (Just wondering why the mechanic decided it was a bad MAF sensor)



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