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Old 05-02-2022, 01:58 PM
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Originally Posted by workingonit View Post
I can not say for SURE that there isn't a vacuum leak anywhere, but I spent hours looking for it. If the fuel pressure check yields no pertinent info that leads to a solution, then I'll starting checking for leaks, again. Isn't P0313 pointing in the direction of low fuel pressure at times? I'm thinking that somethings not quite right with the MAF, but can't throw $160-$$$ at it, getting a new MAF to test, just to find that the MAF wasn't the problem.

My responses:
  • 1) I've never had a difficult start, random or otherwise, and it idles very smoothly
  • 2) the previous owner says he replaced the fuel filter assembly (which I assume means the FPR+fuel filter) less than a year before I got it from him, so odds are it shouldn't have gone bad that fast
  • 3) there'll probably be needle wiggling no matter what, from a cheap Chinese gauge; I'd have to step up to a dampened liquid-filled gauge to get a truer picture, wouldn't I?
  • 4) that's a good suggestion, I'd not thought about; it should test the O-rings at the FPR and at the injectors, too
  • 5) frankly, I'm hesitant to rev the M54 to WOT; it might open a Pandora's box of other problems I don't have (yet)...this X5 is OLD, and retired like myself, not a racecar as in my past
Yes, I agree with not throwing money at a new MAF until you absolutely confirmed that it is condemned.

If you don't have a cold-start struggle, that would suggest your FPR is not leaking, I would say--which is good as it appears it's keeping prime. Perhaps it might be worth taking another look at the fuel filter--since you said it was replaced by the PO? Usually when you replace them you can strike the fuel filter a little bit and see "brownish" goo come out with residual fuel emptying out. Now that I think about it, they did have a changeover part on the fuel filter from the earlier 2000's X5 M54s to the later ones.
2003 BMW X5 3.0i -- MT5, 3.64s final gears, H&R lowering springs, K-Mac bushing kit
2007 BMW X3 3.0Si -- MT6
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