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Discussion Starter · #1 ·
I'm chasing down a fuel related problem on the '05 2.5T. I get an ECM-2900 in VIDA "Fuel pressure - faulty signal". I follow some diagnostics and the fuel pump test comes back OK. One pressure test shows ~400kPa. Another shows ~300kPa. Not sure how I found the two different tests or why the results were so far off. Also seeing duty cycle of ~57%. Car runs decent, not great, but going through fuel more than usual.

With the low pressure in the one test it kind of makes me think the FPS is the culprit, but....

A little background; Had a fuel issue where it would cut the supply with high demand (like accelerating to merge into traffic). Very scary. Went with this sensor only about 5 months ago because actual item is a Bosch (plenty of threads about this topic). Seemed to resolve the cutting of the fuel problem. Spark plugs have about 22K on them. MAF and PEM have been swapped with no change in performance. Fuel filter brand new. O2 sensors probably original?

So what do you guys think? Could the fuel pressure sensor be faulty? To the point where the car has a high duty cycle? Or is it most likely the fuel pump? Or even one of the other items (like MAF, O2 sensors, etc)?

I appreciate any help or suggestions you guys may have!
 

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Discussion Starter · #3 ·
Check the PEM in the RR wheel area.
Ya, I did check this and it appears to be in pretty good shape (at least upon visual inspection). As mentioned above I even swapped it and got no change in code/mpg.
 

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I believe expected duty cycle at idle is 35% +/- 5%.

I suggest replacing the fuel pump.

I recently replaced a fuel pump and monitored duty cycle at WOT. I saw 50% duty cycle at WOT and ~35% at idle.
 

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if its 35%+/- 5 then i would replace this fuel pump. double check vida for proper spec. some cars have 50%+/- 5 in that case ur pump would be ok.
 

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Discussion Starter · #7 ·
I believe expected duty cycle at idle is 35% +/- 5%.

I suggest replacing the fuel pump.

I recently replaced a fuel pump and monitored duty cycle at WOT. I saw 50% duty cycle at WOT and ~35% at idle.

if its 35%+/- 5 then i would replace this fuel pump. double check vida for proper spec. some cars have 50%+/- 5 in that case ur pump would be ok.
Thanks for the sanity check. Just wanted to make sure before replacing without good reason. I believe the duty cycle is supposed to be in the mid 30% range on this car but I will check again. The car is 10 years old with over 160k so a new pump couldnt hurt...
 

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Discussion Starter · #8 ·
Well after touching the old pump (by stupidly taking it out to inspect and putting right back in) I made matters worse and car began to sputter like it was starved for fuel after running fine for a short period of time. Eventually it would just die. If I waited 5 mins then started her back up again, it would run fine for a few miles, then sputter, then die. Took several of these cycles to get it home.

Sooo, I figured time for a new pump. Put that in. No change :(

Am I pinching a hose when I put the pump in to cause this behavior? I don't see how. Pump does take some maneuvering to get in place but seems to only fit one way.

Do I have something clogged in my fuel lines that doesn't affect driving after starting car until several miles down the road?

I am leaning towards fuel pressure sensor now but really am kind of lost. Vida shows FPS values all over the place but also still shows high duty cycle from pump.

Any help would be greatly appreciated!!!!
 

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Discussion Starter · #11 ·
Ok so replaced the Amazon FPS with the Bosch that is for these turbo cars. No change. Tried several PEMs. No change. Took to Indy and they replaced pump then gave up. All signs point to this http://forums.swedespeed.com/showthread.php?222791-Fuel-pressure-drop-on-right-turns&nocache=1450975000667

In that thread it talks about fuel pressure dropping on right turns. After hooking up mechanical fuel pressure gauge this was very evident. There is a valve that supposedly gets stuck open by dirt and the fuel can't stay in the reservoir. While this was certainly occurring, I also got the symptom where the car would just die while idling or driving. Seems as if the PEM will correct the low pressure situation several times before giving up. Or maybe the ECM gives up (trips something) because after several cycles of low pressure and then a spike of pressure to correct, the car no longer would cooperate resulting in starving and stalling. Took me several cleanings of the screen under the pumps and the pump housing itself.

Been running good for a few days now. Be careful when replacing your pump as there is potential for all kinds of dirt and foam to fall in your tank. Hopefully dirt is all it was!!!
 
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