Fredysan

I'm using an autometer A/F meter in my MY98 Impreza turbo, which never had reach the rich zone, even in a wide open throttle condition.

Yesterday, I went to the subaru dealer a little bit worried about this and they use the select monior, in the WOT operation the lambda sensor showed up to 0.84 volts...

Is this a simptomp of some kind of problem?

Regards

nom

Most likely it's the symptom of a dodgy lambda sensor! They under-read as they get old, so can read lean when the fuelling isn't lean, and will over-fuel on cruise giving seriously bad economy.

Fredysan

Actually, I made some tests in order to find out the problems:

1.- Replacement of the MAF sensor, there weren't any differences
2.- Inyectors, throttle body and flowmeter cleaning. Before we did that, the lambda sensor show 0.74 V....
3.- The fuel pressure is about 32 psi at ralenti which is normal

With this aditional facts, Could be another stuff different of the oxy sensor?

nom

It's still seems the most likely. If the garage had measured the actual AFR (rather than what the lambda was reading) I suspect the mixture would have shown up as correct.
A lambda probe should be considered as a 'replacement' item at around 30,000 miles / 3 year mark, but for some reason there is no standard service point. They do wear out after this amount of time!

wrxmark

Just had mine replaced after running problems pre-boost.
Symptoms were as follows
Too rich pre-boost, leaning off to somewhere near normal on boost.
Flat spot when revs drop below 3000 rpm and slight throttle is applied.
Apparently if the sensor is still sending a reading albeit a wrong one to the ECU no fault will show.
Mine is looooverrrrly now. :0)

Fredysan

Thanks guys!

I'll replace the oxy sensor... I hope this be the problem...

Regards from Chile