Idling problem
 

HI.

The MAF went on me yesterday, now have changed it, and ECU reset.

Now its idling funny. revs keep dropping and sometimes stall.

Spoke to the place I bought it and they said check idle control valve.

But one thing, why would it do it just after MAF went?

There isnt a CEL light on.

Please help, its embarrassing at the lights trying to keep it idling.

You sure the new one is OK?

please dont say its a second hand MAF as this is the cause

Hi Mrchips my car was doing this the outher day and i took my idle control valve out and cleaned it and all is good now

maybe it wasn't the MAF after all...

ERM, yes it was second hand only to get me back on the road. As need it for weekend. I know this is bad, and shouldn't really do second hand on these already made of chocolate MAF's but needs must and all that. I will be buying new asap.

So can MAF cause idle problems as well and not through up CEL?

I have a look at idle valve, this is the one on throttle body above throttle position sensor? And gave it a dam good clean as was proper mucky. It has made no difference.

So as Kickboxingcrazy says maybe it is down the the MAF as secondhand. God dam.

Has it only started since the refit? Or did it start, so you changed it? Because it may not be the MAF at all...

Yes, it can. Airflow meters can knacker in all sorts of ways and not illuminate the CEL on a standard Subaru ECU, unfortunately.

Secondhand ones are best avoided no matter what the circumstances, as you don't know their usage history and can never rely on them 100%. The MAF is the most critical sensor on the car and you must be able to rely on it totally.

If your reference to "chocolate" mass airflow sensors implies that you have a 99/00/STi version 5/6, then there's even less reason to buy a secondhand one as they're the cheapest to replace brand new. And, again if this is type of sensor you're after, the new ones aren't "chocolate", and haven't been for years.

The following test might help you discover whether this "new" sensor is duff (and assuming you're running Subaru, as opposed to Apexi management):

Unplug the airflow meter, start the engine (CEL will be on), and drive around a little no faster than traffic jam/parking speeds (i.e. single or low double figures). As yourself whether the idling/stalling problems are noticeably better. If things are noticeably improved, then that sensor's definitely shot. If there's absolutely no difference to the idling issues then it's quite likely that the problem is elsewhere.

Incidentally, does this "new" sensor have the stripe of green paint on the top of its mounting flange? If so, what is the first number of the four digit code printed in white ink on the lower part of the flange?

I see what you're saying re. needing the car for the weekend, btw, but driving on a potentially dodgy one is a very bad idea. If you have to drive it, stay off boost completely or you could inadvertently cause a surprisingly expensive amount of damage in a surprisingly short time.

I am running standard ECU.

This is the third one which has gone. I bought one brand new only 3 months ago.
This one had a green bit of paint on it. Will check code for you and get back to you on this.

I think I will order one on monday then and get it on asap.

All the trouble i have had with the car, and this MAF issue. Thinking about going Syvecs ECU with an 18g. But need to save some dollar for these items.

Why oh why did i buy this thing. What a donut.

Thats the one thing with imprezas - do it properlly or not at all. On the cheap, unless lucky, will always have a bad come back.

Yep first time I have gone on the cheap to get it running.

Think i'll be taking this back and getting money back.

The code on the side near green strip is C36-700 R92 if this means anything to anyone. This is the one i have taken off, not the secondhand one.

Mr chips, is your car standard, or does it have an induction kit?

I has the standard air box, it has been modded though. Where the bottom has been taken out and a proper bracket made.

Beware the old saying about the workman and his tools.

If you are killing green stripe sensors that quickly, there is probably a reason it is happening. Three years would be more reasonable than three months. I've not yet managed to break one, despite considerable abuse (touches wood). Four years and change. Nearer five now in fact.

What, exactly, do you mean by "proper bracket"? There's nothing wrong with the way the standard part is secured to the chassis, so difficult to see how something else could be improved. Does this "bracket" bolt the airbox solid to the bodywork, or is it still isolated on rubber bushes, as per the OE part?

Is the resonator still present and also, have you retained the standard flexible rubber joint pipe between the MAF tube and the intake tube, or has it been replaced - for example with one of the metal ones we've seen here in the past?

Oh - edited to add. What filter are you running?

Further edit:

Nah all the green stripe ones have that on them, it's obviously the supplier's internal part number. The other (four digit) code is more useful as it's a manufacturing date/batch number.

Is the secondhand one also a stripe unit? If it isn't, I hope you didn't pay any more than 50p for it. Even then it could work out expensive if it damages your engine.

The bracket does the same as the original, except this doesn't have a bottom to it, it is open so you get the induction noise. And yes still has rubber bushes.

I have a zero sports pipe between maf and intake.

Panel filter i am running is the HKS super hybrid.

Oh and yes the secondhand jobby does have the green strip on it.