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Discussion Starter · #1 ·
I recently had my M5 on repair, since only 4 of 8 cylinders fired up. I turned out to be a faulty solenoid for the vanos and one of the MAFs (you´ve heard this before). Anyhow, after they have exchanged these unit units and cleared the engine from erorrs codes, it goes like s...t.
The engine hesitates after 4000 rpms. And if I push it, the car enters limp home mode.
I went back to the dealer and the only error code that showed up was that the fuel level was to low even though I almost had full tank.
Strange, don´t you think?
Any suggestions, anybody?
Will it help to clean a new MAF?
 

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What Josh said ---^ Bad MAF's .
 

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Read some of 'DavidS' recent posts on this. crappy BMW mechanics just say 'no MAF codes' ... the codes only show when the MAFs are dead.

He's posted some instructions on evaluating their functionality at high flow rates- which might be where yours are flaking.

A
 

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Does your fuel-level meter on the dashboard work correctly?

I think the problem is one or more of these:

bad fuel-pump
clogged fuel filter
bad fuel pressure regulator

So, I´d like to suggest:

1. Let the dealer check the fuel pressure.

2. Check alignment of the crankshaft sensor (CPS).

3. If there still are misfire troubles, unless the car already has the redesigned camshaft sensors, replace two of the camshaft sensors.

4. When the car runs on eight cylinders at WOT at 7k RPM, then Perform the MAF (fuel-flow) test yourself. See:

http://www.m5board.com/vbulletin/showthread.php?t=54788

David
 

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Discussion Starter · #6 ·
The car was much more aggressiv on the throttle than it is now after they changed the MAF, even with only 4 cylinders igniting out of 8. You have to really press the acelerator hard to make something happen.
They took my M5 away from me and rerplaced it with a 530 i.??????
 

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If you have the gearbox in neutral and rev the engine slowly, with just a little bit of throttle, does it rev clean?

David
 

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Discussion Starter · #8 ·
It seems that it revs clean when standing still and in neutral, but when I drive it and press the throttle, the car really lacks power and is very slow on revving after 4000 rpms.
 

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Good. That pretty much rules the camshaft and crankshaft sensors out as the source of the problem.

(Those have undergone a a major design change, and sooner or later those of the old design will need to be replaced.)

That leaves the fuel pump, fuel filter and fuel pressure regulator.
Get the fuel pressure checked, and request that they do it by the book.

That means:

1. Measure fuel pressure with vacuum hose to the fuel pressure regulator connected.

2. If ok, then measure with vacuum hose disconnected.

3. If ok, disconnect the connection to the fuel-rail and measure fuel flow into a bucket.

Of course it could still be a MAF problem as well, or the fuel injectors, but I think it is the fuel supply.

David
 

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Discussion Starter · #10 ·
Ok, thanks for the extensive support and fault tracing. I will let them check on the fuel presure as soon as time is given.
Bytheway, when did design of the camshaft and crankshaft sensors change?
 

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Camshaft sensors

It is the camshaft sensors for the inake camshafts that sometimes cause trouble, mainly on Bank 2 (left side of the car).

The part number for the new type of sensor is 12 14 7 833 134.

Those were implemented on cars manufactured starting July 11th 2001.
VIN number BZ99615 / engine number 60892566.

There has been no changes to the exhaust camshaft sensors nor to the crankshaft sensor.

The problem you have described can also be caused by a bad Vanos valve,
but if you have the old type of camshaft sensors that is more likely to be the source of the problem.

David
 
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