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Premium Member
2003 330ci Convertible Sport package
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164 Posts
Discussion Starter #1
Hi! Here is the situation. ONLY on first start after sitting for at least overnight. Starts perfect, idles perfect. Pull out and first bit of acceleration there is a bucking like a a miss, or maybe fuel pressure? I just replaced coils, plugs, fuel filter, had an induction system clean 20k ago so I know its probably not fuel injectors. New O2's etc. I was thinking first signs of fuel pump issue? Only reason I'm dubious of that is it fires RIGHT up no matter the conditions. Is there a spot to start? Just started happening last few weeks.

THANKS!!!
 

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E30M3 Race F10 535 R1150Rt M Coupe
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2,927 Posts
More coffee?

All kidding aside, you can hook up a gauge to the fuel rail and monitor pressure. See if it falls off the mark when cold?
Open hood in the morning, remove fuel rail cover. Unscrew cap (don't loose it and put it back when done!) Screw on the gauge. Cycle the key a few times (NOT starting) to prime the rail from the lost pressure. Start and monitor pressure.
 

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Premium Member
2003 330ci Convertible Sport package
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164 Posts
Discussion Starter #3
Awesome, I will do that. I will leave it overnight here at my shop and see how that goes. It just is so non-symptomatic other than the first acceleration when pulling out. It fires right up, idles perfect, and runs great once the first pull away. I thought it was a missfire but INPA says NOPE. LOL I drink about a pot of coffee, maybe I will share with the old girl. LOL
 

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Premium Member
2003 330ci Convertible Sport package
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164 Posts
Discussion Starter #4
You know what? I decided to order up a fuel pump. Research is showing that my car with 126k is on borrowed time with my stock one anyways. So I'll throw that part at it as preventative and hopefully it solves the problem. I also get less than consistent off idle performance, so maybe they are related?
 

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E46 F10 W204 W212
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5,100 Posts
When my fuel pump soft-failed (which is what you're thinking) the symptoms were confined to WOT, not idle. That sad I wouldn't mind changing out a 127k-mi fuel pump. Report back how it goes.
 

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Premium Member
2003 330ci Convertible Sport package
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164 Posts
Discussion Starter #6
When my fuel pump soft-failed (which is what you're thinking) the symptoms were confined to WOT, not idle. That sad I wouldn't mind changing out a 127k-mi fuel pump. Report back how it goes.
Mine is fine at idle, just at the first acceleration after startup. Around the house at 25 or so no issues, then go to accelerate to speed at any throttle more than 1/4 that is when it acts up and only for that first acceleration, or MAYBE 2 if pushed harder. Like 2-3 lumps during, then smooths right out.
 

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Premium Member
2003 330ci Convertible Sport package
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164 Posts
Discussion Starter #7
Also, thinking with understanding my DISA works fine, the Vanos seal job may help my low end bogging? I can flat punch it from stop and VERY seldom do I see the traction control light. Maybe normal? I take VERY spirited runs on my 40 mile trip to and from work. And no winter driving, so not gummed up. My other E46's with the 3.0 seemed more responsive, I am updated to latest software etc. Maybe my expectations are too high?
 

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Premium Member
2003 330ci Convertible Sport package
Joined
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164 Posts
Discussion Starter #8
When my fuel pump soft-failed (which is what you're thinking) the symptoms were confined to WOT, not idle. That sad I wouldn't mind changing out a 127k-mi fuel pump. Report back how it goes.
Pump in, took for a very short drive this morning cold, and only happened when almost full throttle and only twice. It was during secondary pump run time, so maybe there is something to that?? I will drive tomorrow for my full 90 miles a day and see what happens. Seemed to drive normally after install on way home last night. So smoke test Sunday, but starting to think it's just a 126k BMW LMAO
 

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Premium Member
2003 330ci Convertible Sport package
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164 Posts
Discussion Starter #9
In my theme of updating my threads, this was solved with drain and refill of transmission with proper level. I was at least 2 quarts low, and was leaking. Replaced o-rings on trans lines after, and the leak is gone also.
 

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Premium Member
2003 330cic, 2003 325iT
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4,857 Posts
In my theme of updating my threads, this was solved with drain and refill of transmission with proper level. I was at least 2 quarts low, and was leaking. Replaced o-rings on trans lines after, and the leak is gone also.
Thank you for following up!
 
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