740 Stumble under early accelaration

The problem started after a new fuel filter. After the new filter the main pump started whining and making all sorts of noise so i went ahead and replaced it thinking i somehow shorted it. Since then, ive replaced the knock sensor, coolant temp sender and tried a different fuel pump relay with no luck. I took off all my intake hoses to inspect, and cleaned out the intercooler. There seemed to be a sufficient amount of oil in it although its only been a couple months since i cleaned it last. I know the turbo is spitting SOME oil into the intake but i dont think its affected the cat just yet. It needs a rebuild. All plugs and wires are under 3000 miles and i have new gaskets all around, engine was running great before this issue. Its almost like at 1000-2800 rpm in first and second the engine falls flat on its face and acts like its receiving zero fuel, i cant be certain but im sure its misfiring. Once about 3000 rpm in any gear it has no problems, boosts normally and responds well.
Could i be a bad 02 sensor or possibly ignition coil? AMM or FPR? Any suggestions welcome, the local shop wont take a look since they dont have any Volvo experience.

Have you checked your fuel pressure?
What plugs are you using?
Have you TESTED for boost leaks?
What mods?

EivlEvo said:

Have you checked your fuel pressure?
What plugs are you using?
Have you TESTED for boost leaks?
What mods?

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Havent checked the fuel pressure.. Cheap autolites i believe, running at .028 gap.
Havent tested for boost leaks but wouldnt it be more pronounced when boost is in at higher rpm?
16t at wastegate psi, cone filter, muffler delete and good stage zero.

I originally thought it was a large boost leak. After checking my hoses and driving some more the issue became more pronounced and my vacuum still read -20. I replaced most vacuum lines, excluding iac and some of the hoses to the break booster.

If it started after the fuel filter that's a pretty good indication that you should be looking in that area. Did you kink the line between the pump and filter when tightening the banjo bolts? Could there be a kink in the rubber low pressure line to the main pump? Did you get a defective filter? I've never seen that happen but anything is possible. Your O2 sensor, AMM and ignition coil are not making the pump whine, I can tell you that much. In my experience a main pump that whines is either insufficient supply due to a bad pre-pump or clog, or an obstructed output due to kinked line or bad FPR. Measuring the amp draw of the pump can also provide clues.

James10952001 said:

If it started after the fuel filter that's a pretty good indication that you should be looking in that area. Did you kink the line between the pump and filter when tightening the banjo bolts? Could there be a kink in the rubber low pressure line to the main pump? Did you get a defective filter? I've never seen that happen but anything is possible. Your O2 sensor, AMM and ignition coil are not making the pump whine, I can tell you that much. In my experience a main pump that whines is either insufficient supply due to a bad pre-pump or clog, or an obstructed output due to kinked line or bad FPR. Measuring the amp draw of the pump can also provide clues.

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After the filter was replaced the old pump started whining, i replaced that one and am certain theres no kinks in the hoses or between the pump and filter. The whine is gone but the issue still remains. Im not sure how the filter could be defective unless it was clogged?
The car still runs well in high RPMs.

With the whine gone could the 02, AMM, or Coil be causing my problem?
Ill have to check the in-tank pump next and test the amp draw from both pumps.

Bump!

Did you install the filter backwards? It can happen.