I have a 1989 740 GL b230f. When I accellerate, the car spits, sputters and backfires. Turning on the A/C makes it even worse. So far I have replaced the O2 sensor, throttle position sensor, the ignition module, both fuel pumps. Two different shops looked at it and cannot figure out what is wrong. Any ideas?

 

Maybe Mass Flow sensor.
Do you have any Vaccum leaks?

 

No vacuum leaks, both shops said the MAF was good (they were both Volvo shops).

 

Did they check Fuel pressure under Load?

Has the Rear main oil seal on the Crank ever been done?
Did the problem come up after is was done?

 

Don't know if they checked the pressure under load or if the rear main was ever done. The main was not done within the last 2 years. The backfiring etc. is much worse under load and after the vehicle has warmed up. Unplugging the temp sensors doesn't change anything. I have replaced both fuel pumps and the fuel pressure regulator.

 

What kind of tune up parts do you have on there? Dist. Cap,rotor,wires?

 

Genuine Volvo parts. Both shops checked the cap,rotor & wires.

 

Genuine Volvo parts. Both shops checked the cap,rotor & wires.

 

Maybe look into a used computer next.

 

Supposedly the shops tried a different (don't know if it was new or used) computer.

 

Make sure they are the Same Numbers.

I will try to find out some tomorrow.