850 problems, stumped !!

[StevensVolvoNasty]

hi i have a 94 850 turbo. First things first. It all started one day when i was driving, i was cruising along, and decided to have fun with the turbo and floored it, it lost power shortly after flooring it, and then picked itself back up and kept going. when i came to a stop the rpms dropped really low below 1krpms. it shuttered, and then died. this is all the car does now is shutter and fall on its face. i got 3 codes from all this. MAF sensor signal. Egr Temp Sensor signal. and Rear O2 sensor signal. I know for a fact the rear O2 sensor is bad, its been bad for a couple weeks now. I know the troubleshooting for finding out if the MAF sensor is bad, turn on the car, keep it running, unplug the MAF sensor, and if the car runs better, the MAF sensor is bad. However, i have no clue what The Egr sensor signal code is. One guy told me to try cleaning the Egr valve incase its stuck open or shut. do you guys agree this could be the problem? if so, where is it located? if you could post a picture to show me that would be great. if that doesnt fix the problem could it be the Egr sensor thats gone bad?

[jblackburn]

Nah, don't do that with the car running. Disconnect the mass airflow sensor and THEN start the car. If it runs fine and drives around (it will be down on power, but should hopefully drive around)

I think the falling on its face probably is the mass airflow sensor gone bad. I killed one in a Buick doing the same thing when I was 16 - thought I broke the car

Here's the write-up for cleaning the EGR port:
http://www.google.com/url?q=http://www. ... X3GTDNcYpw

[Shish-kabober]

I've been dealing with a bad MAF for over a year.

(can't afford paying for service, or a reader) Found this forum last year when things really got bad and THANKS. I built the blink reader and began systematically troubleshooting.

Why so long?? It has been temperature sensitive.
In my case between 44-48 deg F (by dash temp indicator) . It would go real flaky in the boost range, but usually remain running if you kept it out of the white, then clear up as it warmed out of the "zone". I had a 35 mile commute to school, so 'nursing it along' for 3-5 miles was acceptable/required. Now warmed, no issues till the next morning or if a cold day, then I'd expect it on the return trip. If I parked it for a 20 minutes while it was malfunctioning, (after a 1 mile drive to the coffee shop & enjoy a muffin) it'd likely behave. Only 4 times in the year+ did it have starting problems. Yup, 47 degrees! It seemed that leaving the key on for 10 mins or so would help - not much else you can try to warm up electronics, or perhaps it was emotional heat from the driver.
The temperature issue really compounded the difficulty nailing it down.

But I finally sprung for a new MAF in April 2011, cause it wouldn't start - at school of course. [ The real no-start issue wasn't the MAF -- it was a fuel pump control issue - partial prime @ key-on, but wouldn't finish and maintain pressure. Hard-wire to dash switch - solved.] In the 2 weeks it took to get that sorted out, ( there was a jump-start on a flat battery, followed by an alternator/VR issue to fix first) the outdoor temps warmed, and didn't spend any time "in the zone" so I didn't know that I still had an issue. This summer, I again was having issues this time in the 76-80 deg zone. But how could that be with a new MAF? Could I have a main computer issue?

Well It's back to the 48 degree zone and so with "similar symptoms" It's been warranty-replaced it yesterday. Reset the codes, & have only had one drive, so no warm fuzzy feeling yet.

Hope your experience is more concise!!

Scott