I've posted for help on the Volvo forums but no one seems to know the answer. I've always thought the people here really know their stuff and are very helpful and active so I thought I would post this here.
A couple of weeks ago my Turbo Charged 2001 Volvo S40's check engine light came on. Didn't notice anything wrong with the way the car drove but just a little issue with idle every once in a while. Took it to Autozone and the codes pulled were PO171 & PO236.
I did some research and decided to clean my MAF sensor. Once done I took it for a test drive and it was taking off like never before. Thought I had the problem fixed but tried to test a passing situation at 50 mph and the engine started surging.. it would rev then fall which would cause the car to jerk around. One time I heard a clicking sound coming from the engine. When I got to the next light it idled fine but died as soon as I let off the brake. I restarted and it drove fine while driving normally.
Did some more research and found a person with the exact same problem. He changed the MAP sensor on this intake and it cured it. I did the same but it seemed to make the problem worse. Right off it through PO171 again and PO237 this time along with an engine misfire. I started noticing problems with idle and it dying after being stopped at a light. So I swapped it with the sensor on the fuel rail and the idle and dying problem are gone but it is still surging when I try a passing scenario. I also haven't had a check engine light come on since. I have driven the car about 200 miles and still no check engine light but still having the surge. I can accelerate up through the gears sometimes with no problem and other times it will surge when it gets in the high gears. Always seems to happen when I open the throttle in higher gears but only occasionally in lower gears.
Anybody got any ideas on what to check next? I don't want to keep throughing parts at it but was thinking for changing the MAF next. I also need a good scanner that could test the sensors live if anyone has a recommendation.
A couple of weeks ago my Turbo Charged 2001 Volvo S40's check engine light came on. Didn't notice anything wrong with the way the car drove but just a little issue with idle every once in a while. Took it to Autozone and the codes pulled were PO171 & PO236.
I did some research and decided to clean my MAF sensor. Once done I took it for a test drive and it was taking off like never before. Thought I had the problem fixed but tried to test a passing situation at 50 mph and the engine started surging.. it would rev then fall which would cause the car to jerk around. One time I heard a clicking sound coming from the engine. When I got to the next light it idled fine but died as soon as I let off the brake. I restarted and it drove fine while driving normally.
Did some more research and found a person with the exact same problem. He changed the MAP sensor on this intake and it cured it. I did the same but it seemed to make the problem worse. Right off it through PO171 again and PO237 this time along with an engine misfire. I started noticing problems with idle and it dying after being stopped at a light. So I swapped it with the sensor on the fuel rail and the idle and dying problem are gone but it is still surging when I try a passing scenario. I also haven't had a check engine light come on since. I have driven the car about 200 miles and still no check engine light but still having the surge. I can accelerate up through the gears sometimes with no problem and other times it will surge when it gets in the high gears. Always seems to happen when I open the throttle in higher gears but only occasionally in lower gears.
Anybody got any ideas on what to check next? I don't want to keep throughing parts at it but was thinking for changing the MAF next. I also need a good scanner that could test the sensors live if anyone has a recommendation.