Hello, where is the o2 sensor on my Volvo 740 gl? The car runs great but has lost a lot of power! I changed plugs & they were white on the ends. I have no codes. Could it be the o2 sensor? I also want to say the car is running great! It's idling fine & doesn't miss at all. I did notice that if you get the rpm's up to about 5 or 6 the motor cuts out. Do Volvo 740's have a rev limiter on them?

Thanks,
Scott

 

Aaaaaaaaaaa!!!!!!!! Too many questions at once, so I'll only answer one.

O2 sensor is under the passenger's feet, either directly in the front end of the catalytic converter, or in the pipe nearby. If you have the Regina ignition system (square coil front left) instead of Bosch (round coil right rear), the O2 sensor costs about twice as much, and works completely different. Regina sensors change resistance based on O2 content, Bosch sensors change output voltage. NOT interchangeable.

 

Thanks!! I know to many questions at once! lol

 

They do have a rev limiter, its right at the redline which is around 6200rpm IIRC (I'd have to look at my tach to tell you for sure)

white plugs sound like its running too lean. ideally they should be gray. lean means not enough fuel. if you're saying you have no codes means it must be a 88 or newer with lh2.4. I wonder what kind of condition your fuel filter and/or fuel pressure regulator are in ? the fuel filter is next to the primary (pressure) fuel pump which is under the car, forward of the gas tank, and on the other side of the drive shaft from the exhaust. for completeness, I should say, there's another fuel pump inside the gas tank, along with the fuel gauge sender, this in-tank pump primes the pressure pump.

to test the fuel pressure regulator, you need a special fuel pressure gauge, something you'd find at an import garage, and is probably best left to the pros who have such. LH systems should have 43 psi above manifold vacuum (at idle, manifold vacuum is likely -9 psi or so).