WILL NOT IDLE WITH MASS AIR SENSOR AND EXHAUST HEATS UP

1999 Subaru Legacy

Tiny

FeldonKane

June, 19, 2012 AT 11:00 PM

99 Subaru Legacy - Without the sensor idles but does not get over 3k rpm. Ok, my 99 Subaru Legacy Brighton 2.2 will not idle with the Mass Air sensor plugged in, everything behind the cat glows orange if forced to run above 3k rpms and shoots sparks out the tailpipe, without the Mass Air sensor plugged in the car will idle when warmed up but does not get over 3k rpms and get about 12 MPGs. I have no idea what is wrong with it, have replaced the Mass Air flow sensor with 2 different ones, spark plugs, valve cover gaskets, fuel filter, cleaned fuel injector valve, and checked the cat to see if it is plugged. I am desperate as I am moving in 3 weeks. PLEASE HELP!

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6 Answers

Tiny

ASEMaster6371

June, 19, 2012 AT 11:02 PM

You need a back pressure test on the cat. Either that or the timing belt is bad causing retarded timing.

Roy

Tiny

FeldonKane

June, 19, 2012 AT 11:09 PM

But how would that work with it getting full RPM range with the Mass Air Sensor plugged in?

Tiny

ASEMaster6371

June, 19, 2012 AT 11:14 PM

What is full rpm in your thinking?

I would start with the basics here and after that move on to other possibilities.

Roy

Tiny

FeldonKane

June, 19, 2012 AT 11:17 PM

With the sensor plugged in it will get up to around 7 to 8k depending on how close to the red line I want to push it. Sorry my Mechanic friend and I have spent close to 40 hours trying to figure this out

Tiny

ASEMaster6371

June, 19, 2012 AT 11:20 PM

Ok, did you do a back pressure test? Did you check the timing belt?

As far as the mass air flow, I would look at all the basics before heading in that direction.

Roy

Tiny

FeldonKane

June, 19, 2012 AT 11:25 PM

Ill be honest with you, I do not know. We may have but if we did it was a while ago as far as the back pressure test goes. I do not think we checked the timing belt though.

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