1991 Volvo 740 sedan oxygen sensor/smog check

tuvmeister · Post by **tuvmeister** » 15 Apr 2004, 23:42

I just took my 1991 Volvo 740 sedan in for a smog check, and it didn't pass because the "check engine" light was on. They fixed the problem by replacing the oxygen sensor. So now the check engine light is off, it passed the smog check, but I have a new problem: it feels like the car is giving gas even when my foot is not on the accelorator, i.e. the car goes faster than it used to when I just put it in the "drive" or "reverse" positions, and it takes more pressure on the brakes to make it stop. What could be causing this? Could it be the new oxygen sensor? If so, is that normal?
Thanks a lot!!

ozzimark · Post by **ozzimark** » 16 Apr 2004, 15:26

interesting, i have that problem too, but it only happens to me when i'm at speed. i've always felt it was because of my idle control motor switching on and off while i'm coasting at speed (generally above 50mph), and this causes a... stuttering feeling. i don't see why switching the oxygen sensor would cause this problem, but perhaps there is a bad connection somewhere.

tuvmeister · Post by **tuvmeister** » 16 Apr 2004, 18:26

now when i brake i feel a strong jerk. this is getting me scared. someone please HELP!!
thanks

Volvord · Post by **Volvord** » 16 Apr 2004, 20:25

There is no relationship between the problem you describe and the replacement of the O2 sensor. It sounds like the idle speed of your car has increased for some reason. Items to check are the throttle cables and their alignment to the "drums" that they act upon to throttle shaft, make sure that all the vacuum hoses are attached, it is quite easy to knock one off while under the hood which will cause a vacuum leak and result in an increased idle speed. Finally the idle control motor may need cleaning and the occurance of the symptoms are purly coincidental.

Good luck