Power loss with altitude

hartmannjoho · Post by **hartmannjoho** » 27 Jan 2011, 15:54

Hello, I´ve heard a lot about your site, I hope you can help me!
I recently bought a 1995 850 Turbo with 74.000 miles. I live in Bogota-Colombia (8000 feet above sea level) and the car runs great in the city. I have noticed a gas smell that comes and goes, specially whenever I get stuck in bad traffic, but since the car runs great and since it disappears after some time, I didn´t pay much attention to it.
Last week I took it for a 450 mile trip. For the first 200 miles it ran great but when I started going up a very high hill (about 10.000 feet above sea level), the car started loosing power progressively with altitude, to the point where I got my foot floored on the gas, and I was going 10 mph and there was a very heavy gas smell. Even in neutral I stepped on the gas and the engine speed climb erratically to about 2000-3000 rpm, no more. I stopped and called my mechanic, who kindly helped me over the phone. We checked all turbo hoses looking for leaks but they were all fine and the turbo system is perfectly working, then he told me to disconnect MAF sensor and to try driving again. Check engine light came on and it worked for about a mile and then it started sputtering and eventually stalled. I had to drive like this (connecting and disconnecting MAF sensor) until I got to the top of the hill, and when I came back down (with MAF sensor disconnected all the way downhill), the problem was gone and the car was running great again.... but every time I start going uphill, the problem reappears.

Any ideas what can be going wrong??

Thanks!!!

Post by **Ozark Lee** » 27 Jan 2011, 18:15

Pull any codes from port A-2 and post them back. If you have not pulled codes before here is how it is done on your car.

http://volvospeed.com/CheckEngine.php

The turbos do have a barometric pressure sensor that really doesn't do much until you are at high altitude and it could be bad. The codes should tell us more if there are any.

...Lee

hartmannjoho · Post by **hartmannjoho** » 27 Jan 2011, 20:13

Hi Lee, thanks for your quick reply.

There are a lot of codes, some of them are old and came on because my plug cables need to be replaced, but these are the codes I read:

153 / 212 / 543 / 452 / 454 / 455 / 542 / 233 / 121 / 545 / 554 / 555 / 544 / 436

I think (please correct me if I am wrong

) that almost all of the codes are related to mixture problems causing misfiring cylinders and/or exhaust problems (H02 sensors). I checked the elbow and it´s not broken.

Any ideas???

Thanks a lot!!

TurboWagon · Post by **TurboWagon** » 28 Jan 2011, 01:28

That sounds like similar symptoms to a bad MAF sensor. I'd recommend a new one, the reason it was losing power when going uphill with it unplugged is because the engine wasn't mixing fuel correctly because the MAF wasn't sending a signal.

Sometimes the MAF gets clogged up by road grime and engine oil blowback, I know mine was looking a little fouled, you could try cleaning it before investing a ton of money in a new one.

hartmannjoho · Post by **hartmannjoho** » 28 Jan 2011, 14:42

Thanks for the bad news, haha ... Mmm ... any other simple faults I can discard before spending a lot of money on a new MAFsensor???

Post by **vjaneczko** » 28 Jan 2011, 15:03

You can buy a can of MAF cleaner which may help. Since the MAF is a very delicate wire, you have to use MAF cleaner - nothing else - and don't try to touch it or you will have to buy a new one.

Other things to do is to make sure the airway is nice and clean. Cleanup the throttle body, new air filter, no cracks in the airhoses, etc. Lookup "Stage Zero" for details on parts to check/replace.

hartmannjoho · Post by **hartmannjoho** » 29 Jan 2011, 18:45

I bought MAF sensor cleaner, cleaned it and work perfectly for about 200 miles, and then the problem reappeared. I´ll have to buy a new one and update.....

Post by **Pauloil** » 30 Jan 2011, 07:45

try clearing all the codes and see if any come back just to be sure