Some of you may have read in the past about my engine not always able to hit the red line and often cutting the power at about 3500-4000 rpm which is most troublesome, especially when trying to overtake.

The only real line of enquiry I've been able to follow is the fact I had it plugged in and got the fault code for bad signal at crank sensor. Had the sensor replaced but the fault reappeared. It seemed a little intermittent and so then decided to try and get the wiring replaced. I managed to get a large section done but the fault still came back. I had also thought about the front pulley being at fault as I know the centre rubber damper can perish.

BUT...... I did a scheduled service on the car last weekend and as a matter of course I decided to take the sump off and check the oil pump bolts. I have read many times of them working loose and people finding a few in the sump.

Lo and behold I found 5 in the sump. Got it all sorted, bolted it all back together, new oil filter and filled with oil. Upon driving it home I decided to give her a blast down a 60mph road and took her up to 4000 rpm expecting the usual engine cut out (feels like someone stamping on the brake pedal) but she kept going right up to the red line! Not completely unusual as the problem seems to be there only 90% of the time so I have managed the odd red line. The thing is, generally the engine feels a little more responsive and I have managed to red line it every day on both journeys to and from work.

It's like driving a new car, infact, it feels a lot like when I first bought it and I got the smile across my face that only a V8 can deliver!

I have 3 theories; either it is/was:

1. A wiring fault, which by dropping the sump down I've moved the wire to the sensor causing a better connection?

2.  Perhaps the oil pump missing 5 bolts caused a slight vibration which in turn caused the damper to vibrate so the sensor couldn't read it at high speeds?

3. The oil pump wasn't keeping the chain 100% true and therefore caused a minute timing issue?

Any thoughts?

Mike

Interesting.

It's always very satisfying that you have been able to fix the fault yourself, plus get it performing like it should.  Well done.

I was going to say low oil pressure, but I can't think that would affect the redline issue, unless there is some form of electronic oil pressure control that retards the ignition?

I'm thinking that a few oil pump bolts missing will mean that the two havles of the pump aren't sealing and you aren't able to maintain full oil pressure....

What http://www.realoem.com/bmw/showparts.do?model=HK32&mospid=47398&btnr=11_1243&hg=11&fg=30 - bolts was it that were loose?

Although was it pump mounting bolts or was it bolts that hold together the pump?

Looking at the pump chain drive it will be a seperate short chain that drives the pump rather than the same chain that drives the cam shafts, it could be possible that a loose pump caused some form of vibration that affected the cam chain drive, although by their nature, I wouldn't have expected a chain drive to carry a vibration effect thru to make the timing miss.

Anhyoo, as K says, well done on the new car

How did you find taking the sump off?

Ususally these things are held in place with a million and one bolts and the front axle cross member gets in the road for taking the sump off or at least being able to withdraw the sump pan over the axle.  I looked at replacing the sump on my Senator as the plug was cross threaded, but I would have had to drop the front axle to do it....after removing something like 24 bolts from the pan to block.

Andrew, sump was easy to come off, just a shed load of bolts, very achy arms after!

Lo and behold, the issue is back! I'm now wondering if it could be a wiring issue. I disturbed the crank sensor wire when I took the sump off so I'm thinking about replacing the whole wiring from ECU to sensor.

Mike

D'oh!

Never mind Mike, at least you prevented something nasty happening with the missing oil pump bolts.

Jeff I take it your beast hasn't thrown up any error codes?