Hello I'm a newbie here but I need help,


the problem I'm having is the car will not accelerate properly, and it the revs between 1500 and 3500 are very poor.the car performs fine when the engine is coldfirststarted in the morning,after it reaches the normaloperating temp its worse.I took the car to the dealer for the tests. engine compression and condition is ok, all 5 cylinders are equal, transmission was also tested and found to be ok, the car has 150,000 miles on it and especially when going uphill you can feel the lack of power better. the car is 12 yrs old and its exhaust,cat or o2 sensor was never replaced. also in the emissions test the thresholds were at the limit.. for example:

Co2 threshold value is between 10.00-15.00 mine was 16.6

o2 sensor threshold is between 0.97-1.03. mine was 1.02


co threshold is between 0.00-0.5 mine was 0.11

so can we say that the cat and the o2 sensor are bad? am I having the lack or power because of these parts? anyone who knows about these things.. please enlight me..

thanks,

 

interestingly enough, my old 1988 Volvo 240 had the same issue; it came and went, and eventually we lost compression in cylinder 4 (it did this for years). It was just my backup college car, so i never bothered to fix it since it barely went any distance. Only when I drove it home 400 miles did it finally go! Still made it home on 3 cylinders..


Anyways, I'm no tech guy, but I'm very curious as to the source of the problem. When I had this issue, I replaced the fuel pump, and pump relay.. still no fix. It loses all power and barely seems to run right.

 

Yes inspect for blocked exhaust.

Other than that, when was the last tune-up? See following thread for tune-up items:

https://volvoforums.com/m_48928/tm.htm

Pull codes from the ECU. If '93-'95, you can do this by yourself without any tester/tool. If '94-'97, you can have it diagnosed free of charge at auto parts shop such as AutoZone. If you decide to visit one of those shops, make sure to tell them that your car is certified for OBD-II, in front of the shifter under the coin holder. They are told that OBD-II only works on cars made after '96 but 850s have been certified for OBD-II since '94.

Also refer to the attachment.


JPN

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