help,i have a my97 uk imprezza,it will run fine and then out of the blue when i come off the gas,the revs drop right down like it wants to stall,it will do this for a while then rev as normal.it drops down and then picks up which it does several times.makes no difference if the car is hot or cold.had it rolling road last week to be checked out,but no fault was found,could it be a plug or one of the sensors.is this a common thing that happens if so please let me know.
cheers

 

You got a dumpvalve fitted?

 

I've got the same on my new age...my mapper said it was to do with the ECU chasing the correct fuel mix at lower revs as my wild cams have over lap until 2500 when she then runs clean...

Mine doesn't stall, just goes down to idle, then up a bit, then drops etc, putting foot down clears it for a while.

 

I had exacly the same a year or so back - stopping at lights or junction was unpredictable, sometimes fine, sometimes dip, once or twice stalled. New MAF sensor was fitted, spot on afterwards and ever since. Get it checked asap as I believe it can do major damage to engine
HTH

 

thanx for the replies,i will get it checked out again.it ran fine today.

 

get your maf checked out there a pain in the **** welcome to scooby net

 

same as above really do you have a vta dump valve? this happened to me when my dumpvalve began to leak causing irratic idle problems, re-circ went back on and prob fixed!

 

I'm sure this question's been asked before but with no search...How can you test a failing maf? I have a secs monitor so I can keep an eye on the AF readings...would that help?

 

the dump valve is standard,it has only got a panel filter and exhaust,these are the only mods under the hood.got it booked in for saturday morning thats the earliest i can get,it is really p***ing off at the mo.you know when you just want to give it but cant.just dont want to cause any damage to the engine.

 

Mine does this but doesn't use a MAF, its mapped through it with simtec sygma ecu. When its warm it is ok.

 

Whats the best price for a decent pukka MAF sensor and where from? Dont really fancy dealer but will if must - just thinking even if mine not maf fault, I'll have a spare if and when it does go pop.

 

i've no idea of the price for a maf sensor,can someone state this who have had one changed.

 

Hi guys, I was quoted £78+vat from the stealers for a MAF for my MY99. Gotta be worth it at this price. I am sure the way to test a faulty MAF, certainly on a MY99, is to have the engine running on idle, disconnect the MAF conection. If it cuts out the MAF is fine, if it keeps going its faulty! I am sure if this does not apply to your car someone will let you know. Good luck.

 

Nice one chap, I'll give it a go..although still waiting on further advice from my mapper also.

 

well had it on the rollers today,trying to find the fault.there was a broken solder connection on one of the three pins in the maf sensor,it was repaired and now seems to be fine.but will have to wait and see,because on the drive to the garage it was driving as normal and not fluctuating.typical when you want it to happen it doesn't and it never done it once throughout the whole session.so fingers crossed.by the way it did not cost me a penny as i had it rollered about three weeks prior to that and it was in the garage well over an hour.so well chuffed with that.let you know how it goes.
cheers

 

That's a relief! Sounds like that must have been it then, all the signs pointed to a MAF problem. Nice to have a story with a happy ending for a change. Top guys for the free session!

 

Bob (as usual) as just edg-em-ecated me on the new age MAF...the wire (with blob) which I thought was the maf "sensor" is actually the heater...it had black Shi*j on it so cleaned that, also sensors inside...Idle now almost 100% stable although sure it will do the dancing thing again because of the cams...after market ecu possible next step...depends on advantages per buck.