is my MAF dead??

[cakepanda]

hi to all

i have a 97 VR4 twin turbo. it has been running faultlessly since getting it a few months back. however yesterday i started her and within a few seconds she just cut out. i can keep her running if i rev hard and shes smooth at high revs.

i disconnected the MAF and now she seems to idle fine without cutting out (i assume in some 'limp home' mode)

does this sound like the MAF is dead/faulty? or could it be a problem with the ECU?

many thanks for your advice in advance!

Mark

[Roberto]

You could try an ECU reset (disconnect the battery for a couple of mins) and see if it just goes away.

Sorry, but its the best I can suggest.
Someone with real knowledge will be around shortly.

[Nick Mann]

It sounds a bit strange. Normally they run worse with the maf disconnected than connected. Can you drive it?

[cakepanda]

not tried to drive it yet. but it revs up fine with the MAF sensor disconnected. the idle not as smooth as normal though i guess.

will try the ecu reset and see if this helps - thanks for your help so far!

mark

[cakepanda]

Ok, tried reseting the ecu and no difference.

update - with the MAF sensor connected she starts and if i keep the revs up she justs 'hunts' revs go up and down wildly and she is running VERY rich blowing smoke.

disconnect the MAF sensor and running fairly well reving up and no smoke.

very confusing.

cheers

[monkey]

Maybe a air leak somewhere?

[Paul C]

maybe vaccum leak, Tps sensor, idle steeper motor is there any other symptons or fault lights

[cakepanda]

hi paul
thanks. no other symptoms. was running fine before. no warning lights except the engine warning comes on when the MAF sensor is disconnected.

are the MAF sensors cheap enough to replace? would really like to avoid the MMC dealerships!

[Nick Mann]

Is it possible you have an air leak in the pipework somewhere? If you are losing metered air then the car will overfuel. This will be far more apparent if driving - lots of right foot will cause worse running than gentle acceleration.

[Physician]

Is it possible you have an air leak in the pipework somewhere? If you are losing metered air then the car will overfuel. This will be far more apparent if driving - lots of right foot will cause worse running than gentle acceleration.

You know Nick ....... I recollect someone else having a slight idle problem recently - but at high revs it was OK!!! What do you think? Would be a hell of a coincidence eh?

[Subaru ETA]

my car had this problem a while back.... the idle stepper motor had actually broken and the broken bit had jammed in the idle air port. try taking the stepper motor out and checking it

[cakepanda]

cheers subaru ETA
where do i find the idle stepper motor?

[Subaru ETA]

under the throttle body. its brown with a plug going to it IIRC

[enyawbrown]

check your camshaft sensor or crankshaft sensor....

[cakepanda]

thanks for all your suggestions guys
strange that after i took out the MAF sensor, replaced it and checked all the hoses and wires, it just started to work again.
i took it to a rally art service depot and they said the stepper motor was way out of adjustment - but whether this was the cause or this happened as a result of the problem remains unclear. they found no other problems.
but, hell - charging £70 plus VAT per hour labor is just bloody unbelievable!

[Paul C]

cheaper than a new maf