Running Problem
 

Hi all. My 99 UK model has developed an annoying problem that has developed a week ago. It has started spluttering between 2.5-3500rpm and the exhaust will bang a bit while this happens. I have to keep it in the lowest gear possible to keep the revs high. For example I cannot pull away in fourth while doing 35 it just starts spluttering and really holding back, and you cannot hold it in 4th at 40 because it just starts juddering, 60 in 5th same again. I only had timing belt, oil new plugs etc 400 miles ago. The only mods on the car are a magnex exhaust system, dump valve and a cheap induction kit that I have never seen before (which will be changed by a k&n as soon as). I have only owned the car three months so do not know anything about its history.
Will get it looked at in the new year but any ideas or anyone had a similar problem? Any thoughts would be appreciated!

MAF
They are weak on the 99/00 models and the IK wouldn't have helped it, best change back to the standard airbox.

Yea, sounds like the MAF

Cheers, its a shame I have got to lose the performance filter but if its going to keep re-occuring then maybe its for the best. Would an engine warning light not come on if the MAF sensor was shot?

Cheers

Most panel filters for imprezas are good for 300bhp anyway.

The CEL should come on but i've found it depends how badly the sensor is failing (e.g. my coolant sensor was failing but the CEL didn't illuminate ,my CEL works as another sensor failed and it came on straight away)

Generally, No.

The MAF still produces a voltage signal that is within parameters ie Idle & the red line. It's just not the correct signal for the actual amount of air entering the engine at the time, so has the effect of fueling at the wrong rate for the actual air flow.

The system will only flag a code if there is a complete failyer of the sensor.

Thanks for the help guys:thumb: