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Discussion Starter · #1 ·
Hi gang. 2005 x3, 2.5, 173K. Runs and idles just fine but when restarting when hot, excessive cranking required, and raw fuel smell when it finally starts. I'm thinking leaking injector(s), not necessarily bad o-rings. Any suggestions for determining which squirter it may be? Me: ASE tech in previous life....Thanks, Aloha, Steve.
 

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Perform leak-down test of fuel pressure; however, if the injector was weeping and bleeding down, you'd also see extra cranking on a cold start. The raw fuel smell is probably due to the extra cranking, not a leaking injector, but that's just guessing without data.

Check for DTCs (even hidden ones), look at your fuel trims, MAF flow rate and A/F & O2 sensor data. The hot start issue is probably due to the vacuum leak that every 173k mile car, especially BMW, is going to have; a cold start is open-loop with a purposefully enriched mixture and can mask an air leak, but a hot start would not see the same. If you disconnect the MAF before the hot-start, and the hot-start issue goes away, that is additional data pointing to an air leak.

All of the above diagnostics are free.

The IAC valve on an M54 is also a maintenance item, either cleaning or replacing.
 

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Discussion Starter · #3 ·
Thanks duke, I've been meaning to do the leakdown test on the fuel pressure- I think that will verify, or not, my prognosis. Since the problem started, the car starts immediately on the first cranking revolution in the morning and will smell a bit, which leads me to the possibility of puddled fuel in the intake tract from the previous days running. I'll throw the computer on it as well. If I'm correct, I'm still wondering how to isolate the offending injector.....Mahalo, Steve
 

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Perform leak-down test of fuel pressure; however, if the injector was weeping and bleeding down, you'd also see extra cranking on a cold start.
My 04 M54-powered E53 had a leaky injector. Apparently there was a bad batch of Bosch injectors from that era. The symptom was hard restart only when warm. Overnight restart was always normal. I guess the extra fuel had time to evaporate enough overnight or the cold engine's natural desire for richer mixture upon startup made it a non-issue. I replaced all the injectors since they were all vulnerable. Looking at the codes, I was able to determine one was newer, so had been replaced at some point. I kept that one for a spare.

AM.
 
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Discussion Starter · #7 ·
You locate it by sending all six to a fuel injector doctor and have them come back with a clean bill of health, for about $120
Yeah, I figured that would be a likely solution. Any idea how these outfits "clean" the injectors? At $20/injector, there can't be much labor involved. I have a sonic cleaner at the shop and was thinking of soaking them in it for a bit...
 

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Yeah, I figured that would be a likely solution. Any idea how these outfits "clean" the injectors? At $20/injector, there can't be much labor involved. I have a sonic cleaner at the shop and was thinking of soaking them in it for a bit...
Replicate the no-start hot-start, and stop cranking the engine before it fires. Pull the plugs and look for the wet or rich-mixtured one. If an injector is weeping, you’ll see it.

Alternatively, pull all six injectors, but leave them connected to the rail. Place the set on a newspaper. Turn the key on and find the wet spot.

To clean them, step-up the tube from a spray can of carb/injector cleaner using rubber hose until you can attach the injector, and use a 9v battery to sporadically fire the injector. When it emits a clean spray pattern of cleaner, the injector is good. Just remember to cycle the injector, or you’ll burn it out.

Or, on your next fill-up, pour 6-8oz of Marvel Mystery oil into the fuel tank. It’ll safely clean and lubricate the fuel system and upper cylinder. I’be got some in my own 195k mile E83 tank right now, and do every oil change. With it running, listen with a stethoscope to each injector, noting the loud one(s).


Buy socks on Amazon, not car parts.
 

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Discussion Starter · #9 ·
Thanks duke, I like the way you think! Marvel Mystery Oil forever! "Honestly So". I was wondering if it was possible to leave the injectors attached to the rail to test 'em. Guess I'll find out.... Aloha, Steve.
 
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