I have a 1999 Volvo S70 non-Turbo that is driving me to drink. The symptoms are:
1) Idles terribly
2) sometimes won't start
3) will not go over 20 MPH.
4) Random misfires (not on any one cylinder. I hear the putter at the exhaust pipe.
5) Correct fuel pressure.

Codes are:
9150 Throttle Posittion (TP) Sensor 1
9190 Throttle Position
720A Immobilizer Communication

I have been chasing the low fuel pressure issue since the beginning since the service manual is emphatic that the spec is 300Kpa +- 1Kpa.

So far I have:

1) Replaced tons of rotten or broken vacuum lines (including a broken hose to the FP Regulator and the Evap canister
2) Replaced the spark plugs.(they were long overdue
3) Relative compression test (Picoscope) All cylinders are consistent.
4) Bypassed the fuel pump relay. (This was the first thing I did...)
5) Throttle position sensor seems responsive on my Verus

Can anyone help? This is driving me crazy.

 

Maybe I am old school, but the first thing I would do is a complete tune up. Since you did the spark plugs, I would add new plug wires, air filter, fuel filter. Not sure if the 1999 has individual coil packs on each plug or a single coil but replace the coil (s), New distributor cap and rotor (again if it does not have coil on plug.) Check the timing, then I would replace the throttle position sensor and do a wet as well as dry compression test with a gauge. Go from there. Another thing to check is the intake manifold gasket. I had a bad one and it caused a lot of the similar symptoms you are experiencing.

 

Sorry to say but unless you like wasting time and money, suggest you just walk away from it. They changed so many systems on these cars starting in MY 99, IMO I would not touch a 99-2003+ volvo with a ten foot pole. Engines were good, but rest of the car's systems were crap for those years.

 

If you have a bad wire or 2 the OBD II system should identify it (them).
Vacuum hoses are 31 on my hit parade for these cars but there are some plastic trees and connectors that are old and brittle too.

 

If the TPS works on another car I suggest that you look at the cable on the Volvo. First check for corrosion at the connector. If it looks corroded get in there with a dental pick or something suitable. Clear as much as you can and then use dielectric grease. Plug it back in and see if that helped. That’s not it? Check the cable as best you can, feel for stiff and or brittle spots. Find some? Replace the cable if possible. Otherwise, cut and splice out bad parts. If you do feel bad spots I’d really try and replace the whole cable. I can’t tell you if that is going to be a PITA or not.

Good luck.

 

Uh, what cable are you referring to?