The Haynes manual says the MAP (manifold absolute pressure?) sensor should output "below 3 volts at idle (high vacuum) to 2 volts with wide open throttle (WOT) (low vacuum)". I have a 96 Outback 2.2L. Are these voltage specs correct? I am concerned that the Haynes manual may not be correct for my particular year/engine.

 

My MAP sensor output is 1.5 V at idle and it drops to 1.4 V at ~4000 RPM.

 

Symptoms: hesitation between 2-3000 RPM.

 

I have added teflon washers under the knock sensor to keep the ECM from giving a code for the knock sensor. I suspect that the O2 sensor is original-- 115,000 miles.

 

Is it for sure that the MAP sensor is bad? It is $180 from 1stSubaruParts.com. Any better price available elsewhere? Or is replacing the knock sensor or O2 sensor a better bet?

The teflon washer thing really doesn't work. I tried it, it made no difference, and the bolt actually came loose, creating more issues.

 

115k on the orig O2 sensor.....it's probably time to be replaced.

 

Check out https://www.subarugenuineparts.com/oe_parts_cat.html

The teflon washer thing really doesn't work. I tried it, it made no difference, and the bolt actually came loose, creating more issues.

 

115k on the orig O2 sensor.....it's probably time to be replaced.

 

Check out https://www.subarugenuineparts.com/oe_parts_cat.html

 

I used Gylon washers (low cold flow form of teflon gasket material) and used thread locker on the bolt. Also torqued it to 16 ft-lbs. Seems to be holding so far.

 

When you say it doesn't work, do you mean that it doesn't stay tight enough or that it still throws a code or that the hesitation is still there due to the knock sensor retarding the timing?

 

My hesitation is still there but is much better with the 2 gylon washers.

 

Thanks for the reply.

 

Mike (BSME '76)

I did not notice a difference in reduction of hesitation with the washers. This was before it came loose. So I just removed them.

 

The "hesitation" I was experiencing was related to the automatic transmission. Once I did my swap, I didn't have any hesitation issues.

Anybody got any reliable specs on the MAP sensor voltages?