Only started yesterday, and it seems to be an on and off thing.......

Car is a 2004 Wrx Wagon.

On coming to a stand still and waiting for lights, or the wife to pop into a shop, I noticed that the rev's are
ticking over at 800rpm, nice and steady, but now and again they drop to the 500/600 mark and its not an even tickover, its more uneven and unsettled, a few little blips of the throttle and it might go back to normal again.

On popping the bonnet, I noticed that when it was running it dips when the cooling fans go on ect and the revs judder so to speak, as soon as the fan goes off, the it ticks over nicely again.

Any ideas?

MAF?

 

Anyone?

I know of only one other persons wrx doing this.
He has no clue either.

 

Someone here must be having a similar problem!?

 

A friend of mine had a similar problem with a Toyota Starlet. We found that whenever the fans came on the voltage measured at the battery would drop by about 2V for a second. We didn't solve it conclusively but he replaced his battery and raised his idle slightly and the problem went away.

 

Sounds like it could be the MAF

You could try disconnecting it whilst the engine is running, if it carries on doing the same then it is faulty

If the engine cuts out dead it should be ok

 

Is that ok for it to cut out like that?

Is it going to spring any error codes?

 

Yes it is ok for it to cut out like that, if it does cut out it means your MAF is fine

Once you unplug it, it will report it as an error code should a diagnostics device be plugged in

 

Well its worth a go!

Thanks mate,