Failing Maf??
 

Hey guys hopefully someone can help?

Whilst driving home tonight (fairly spirited) I took my car to 5500rpm in third gear and all of a sudden it was like hitting a brick wall! The car violently cut out or miss fired but once it happened I back right off.

Car drives fine, sounds fine and it doesnt do this all the time but something must be a miss.

This has happened twice in the past few days, I only had the MAF sensor replaced some six months ago, would it be on its way out or could it also be something else?

Car is a UK spec Impreza Turbo (year 2000)

Any constructive help appreciated.

do you have oe airbox or cone style airfilter?

this is veru interesting as the same thing has happened to me a few times on my 03 wrx. i have a typhone style wing induction kit fitted.

could be maf related as they really are a weak point on my99/00.

Could also be fuel cut. Do you have a boost guage? Check it's reading and see if it ever spikes over the usual.

The same happened to me-backfire and then no power...
i've narrowed it down to oil from the induction kit coating the MAF and blowing it.Have heard that if the circs are the same,then the MAF can be cleaned with clutch/brake cleaner.Unfortunately i've got a new age and you cant clean them so am trying to order a cheap one as i type:(
Have heard better reports about the K+N typhoon so i hope big bad jon is wrong,as i've just bought one:eek2:

I have a working maf of a 2001 bug eye that I paid £30 for only to find it wasn't the maf but a boost solenoid problem.

If ny wants it they can have it for the £30 I paid + couple quid p+P.

SOLD!!!:lol1: PM me please

I have a standard airboxs

Ive got a boost gauge fitted, every now & then it might slightly boost higher, sometime 20psi other times 22psi depending on the weather (cold/hot etc)

When my Maf failed 6 months ago, it was very much the same, but it went in to a sort of limp mode, car would not boost and it would not go past three or four thousand rpms.

Problem is I could go take it for another quick blast and would not have any problems at all, but you just cant help thinking something is wrong.

Ill take it to a garage very soon, hopefully it will be something simple, any further ideas lads?

Run a self test, that will show you if any sensors are at fault.

Just ran a self test, read through the guide that someone has previously posted up in another thread.

It did not indicate any faults at all, the check engine light just kept flashing at the same speed approxs 1 second between pulses.

Im stumped at the moment, maybe it just needs a good service, new spark plugs etc? as they havent been changed in a fair while.

22psi will make it go into fuelcut.
unless you have some "anti" device installed.
ECU will go into fuelcut if boost is high for long enough time.

Not sure if this is relevant as car was obviously hot, but I had a very similar problem that proved to be my O2 sensor although this was worse when cold it did have the effect of hitting a brick wall, also no error code registered on ecu! I sure someone more knowledgeable will correct me if wrong!

Really? im no mechanic but th car has been mapped and has a uprated fuelpump (Walbro?) so would it really be this?

It does feel like the fueling cuts out but it only has done it twice , other times I could be on boost flat out for quite some time!

I didnt think it there would be a limit to what boost it could run? assuming it has been mapped and has the correct fueling parts etc?

Hitting a brick wall is also how people describe fuel surge. How much did you have in the tank, and was you cornering at the time?

Ah didn't tell it was mapped. if they mapped it correctly fuel cut should not be a problem due to boost. but still sounds like fuel cut. most probably caused by some other problem seen by ecu.
difficult to tell which without the errorcode.

Not corning but going up a hill at the time & only had about at best a quarter of a tank left.

When you say fuel surge do you mean too much fuel was being pumped in at full throttle?

When I had the Maf changed it was put on the rolling road just to check all the fueling was ok, it was noted the car was running on the rich side and you can smell petrol but I thought all Impreza were like this due to them being amazingly bad on fuel consumption!

Thanks for the replies so far.

i had same problem here was hitting the wall at 6000rpm....I turned my mind upside down trying to figure out what was happening...i Changed all 4 coils with a new set..i changed the cam position sensor,i changed the plugs,cleaned the Maf and still same problem....now yesterday i checked the fuel pressure and to my surprise i found the fuel pressure was sitting at 3.5 bar at idle with vac pipe on.....dont know how this happened but i re adjusted the pressure to 2.4 bar at idle with vac on...and took the car for a ride....i did hit the wall another few times but then all of a sudden it dissapeared and power was back on reving all the way to red line....my conclusion is that possibly the extra amount of fuel was glazing the spark plugs making them less efficient especially at high revs and high boost.....at least thats what im thinking...but i also noticed that the boost pressure is back to normal at 0.85bar while when i had this problem it was almost reaching 1 bar...so it could also be that the boost solenoid was clogged and possibly began working again after all the brake cleaner i used...Hope the problem does not come back again on me as it was really annoying.......The Car is a 94 WRX import...
hope that helps a bit to solve your problem although i dont know exactly what solved mine....:)...Cheers Mark

May have been that then if you were under a quarter.
What I mean by fuel surge is not enought fuel getting through to the injectors from the tank/pump. As there is not loads of fuel in the tank, with it swishing around through cornering or going up a hill, the fuel pump is trying to pump something that is not there. Like when you are trying to get the last bit of drink from a cup with a straw. You tilt the cup, but the straw is not near the remaining drink. I hear its pretty common in classics.
I tend not to give it some when I'm under a quarter on the tank just in case.

Saxo Boy is one of the the most infamous victims of this. Read his thread here:

https://www.scoobynet.com/scoobynet-...uel-surge.html

Just read the thread about saxo boy and fuel surge, it does sound exactly like this and it has only happend when the tank has been below a quarter.

I usually never let the tank run that low, well apart from the past two weeks or so, Ill think ill fill the old girl up and take her for a spin and see what happens.

Wish me luck :lol1: