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Discussion Starter #1
This issue is extremely worrying and I desperately need a solution:

When warm, driving at higher revs / 60mph say in 3rd, if I just depress clutch the revs fall down to near stalling, then jump up and down a few times, and sometimes even fully stall.
Here’s a vid from today:

I’ve been posting on Facebook about it and had the usual responses, but I’m pretty mechanical myself so went down the usual roads of trying to fix this, so please try not to suggest the following: (all done in the last year)

new fuel filter, new oem maf, replacement ICV, disa valve rebuild with o-ring, new CCV with new pipes, vanos rebuild with rattle kit, rocker cover gasket, new spark plugs, new intake boots, vacuum leaks from rear of intake manifold changed, new purge valve, oil filter housing gasket, dipstick o-ring, new inlet camshaft sensor.

There’s also no codes!

I’ve suspected it could be the fuel pump, but then surely I’d get other issues.

Any help is greatly appreciated

Thanks
 

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Discussion Starter #3
Have you tested the fuel pressure? As long as the engine is not SULEV, testing is not hard. You want 50PSI with the ignition on, but the engine off. It is not a perfect test, but it may help.
Thanks! just tested mine, it’s at 40psi... does that mean fuel pump is bad?
 

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2004 330Ci 85k miles
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Thanks! just tested mine, it’s at 40psi... does that mean fuel pump is bad?
Yes, it should never be that low with the key in position 2 (run).
Would be good to watch the fuel pressure gauge at various RPMs, and especially while driving.

Pull up the rear seat bottom, remove the cover, look at the fuel pump hose clamp. Is it the original crimp-on one?
You might still have the original fuel pump, which is long overdue by now.
 

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2003 330cic, 2003 325iT
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Yes, it should never be that low with the key in position 2 (run).
Would be good to watch the fuel pressure gauge at various RPMs, and especially while driving.

Pull up the rear seat bottom, remove the cover, look at the fuel pump hose clamp. Is it the original crimp-on one?
You might still have the original fuel pump, which is long overdue by now.
His mileage is quite low, but the lack of pressure says pump.
 

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Discussion Starter #7
Just checked the pressure again with a proper screw on tester, and it’s at 50 for the pump noise, then drops to 45 after the noise finishes, on position 2.

then when running it’s at about 45. Leaving it for 10mins off now to see what it drops to, we shall see.
 

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Discussion Starter #8
That is way too low. Change the fuel pump and the filter. VDO Siemens only for the pump.
So that was wrong, I used a crap tester, I’ve used a proper screw one now and the results are:

key to position 2: 50psi when the initial pump noise is on, then drops to 45psi

stays like this for a while.

starting the car stays at 45psi, then when the cars off it Slowly dropped to 42psi over 20mins.

If that indicates anything or not normal, be good to know, Thanks
 

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Yes, it should never be that low with the key in position 2 (run).
Would be good to watch the fuel pressure gauge at various RPMs, and especially while driving.

Pull up the rear seat bottom, remove the cover, look at the fuel pump hose clamp. Is it the original crimp-on one?
You might still have the original fuel pump, which is long overdue by now.
Maybe.... However we use crimp clamps....FYI.
 

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Discussion Starter #12
Pump should hit 50psi with the ignition (not the engine) on and stay there (pump and regulator). When you turn the engine off it should stay there for 30 minutes (regulator).
thanks got a fuel filter coming tomorrow, will fit that, give it a go, if not then will folk out for the pump next!
Never ending 😂
 

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Discussion Starter #14
It is not exactly endless. It is just a lot!
UPDATE

Yesterday I replaced the fuel filter / regulator and things really improved. First trip out I was convinced it was fixed.

however another half hour drive later that day and sadly not so fixed... it doesn’t stall now, but the revs do drop a bit doing the same thing coming to lights. And sometimes reversing it drops a bit.

I’m convinced it’s the fuel pump...
 

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Discussion Starter #15
Another update:

need help here!
Changed the fuel filter and pump, and did another new CCV, STILL have the same issue!
Please does anyone know?!?!? No codes, nothing!
 

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2003 330cic, 2003 325iT
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First off did you retest the fuel pressure?
Second, the stalling symptoms can be caused by a host of issues, including your idle control valve. Have you removed, tested and cleaned it?

Your initial issue was about cruising speed issues - I presume that is sorted?
 

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I was going to guess ICV. I see you put a new one in...if you still have the old one, maybe clean it really well inside with throttle body cleaner...until you hear it clicking brightly...and try it again. If you get desperate enough...I had that stalling with my e46...and all I did was clean the icv...it otherwise lasted the entire time I had it...386k miles. Not too bad. :)
 

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I hope you figure it out I really love the video I felt like I was actually shifting those rpms are close to what the guy in the bmw in the penzoil commercial was running in the snow it may have been a tire one actually.
 

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2003 330cic, 2003 325iT
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By the way, have you logged the fuel trims? Curious what they are at idle and cruising. If it is not the ICV, then there are a few other causes:
1. Bad DME - very rare, but may have liquid intrusion? Did you check the DME for error codes? Have you upgraded to the latest software?
2. Leaks - Can't remember if you said you had smoke tested
3. O2 sensors - You have such low mileage that it is hard to believe it is a sensor. But thought I would mention

Have you tried running with MAF unplugged? Lots of folks think that is a diagnostic for the MAF (it is not). If it alleviates the issue, then it may be o2 sensors or an as yet unfound leak (did you replace the SAP solenoid hose?)
 

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Discussion Starter #20
First off did you retest the fuel pressure?
Second, the stalling symptoms can be caused by a host of issues, including your idle control valve. Have you removed, tested and cleaned it?

Your initial issue was about cruising speed issues - I presume that is sorted?
ICV has been cleaned and replaced with a tested working used part, so I’m sure it’s not that.

I’ll retest the fuel pressure this weekend. I’m getting a lot of weird issues, it seems like it’s causing inlet camshaft sensors to fail as I’ve gone through two of them now. Very odd. I’ve checked the wiring and that all seems fine.
 
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