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Discussion Starter · #1 ·
I just completed (or thought I had) the longest, most drawn-out project I've ever undertaken. It started out with trying to determine if something in the wiring was causing P0335 (crankshaft position sensor) and P0727 (engine speed sensor). It turned into a marathon of:

R&R the CCV and associated tubes/hoses
Remove and clean TB
Remove and clean ICV
Inspect and test DISA
Remove intake manifold
Replace intake manifold gasket
Remove and replace oil filter housing gasket
New Serpentine Belt
New PS Reservoir and low-pressure hoses
A LOT of engine cleaning
Test for continuity of wiring (all the wiring checked out, and I've already replaced the CKP, so I guess it's either the sensor deep in the tranny or the ecu)

Oh, yeah: it's an '00 (11/99) 528iT automatic; motor variant is the M52TU. The tranny is the asr360, I believe.

Before, the motor would eventually start, even with the P0335 and P0727 codes. You just had to try several times and let it turn over for a long while each attempt.

Now, however, after 20-30 seconds of engaging the starter, right about when the motor would usually fire up, the motor begins making a violent snapping or striking noise.

I've done this twice, and each time halted the moment the noise begins. I can't figure where it might be coming from; it sounds forward of the starter, but not the starter itself...maybe?

Some Considerations:

1) At first I was terrified that that something hard and unyielding had fallen into the intake while it was off and I didn't notice. But the sound only occurs after 20-30 seconds of engaging the starter. If something was getting chewed up in the valves, wouldn't it be heard immediately?

2) With the manifold completely removed, there were a lot of connections, electrical, vacuum and fuel to manage. I'm confident that I've gotten these right: after all, I had to re-remove it 3 times to correct mismatched connections.

3) Prior to removing the fuel lines, I followed the Bentley's suggestion of blowing compressed air through the schrader valve. I think at some point I heard it gurgle back to the fuel tank. Too much? It sure was nice being able to remove fuel lines without spilling a drop of gas.

4)

5) Whatever it is, it's not generating any new codes. I'm working on getting a copy of DIS up and running, but I've tried before and never been successful, so we'll see.

Any ideas on what the noise could be? If someone thinks it might help, I can try to make an audio file or a video and host it.

This is killing me. I haven't driven the car since before Christmas, and I've used up almost every favor I could call in to borrow/beg a ride from others.

If you've made it this far, I'd really really like to thank so many of you for sharing your knowledge and experience. Especially cnn and Graham, and of course...

Bluebee. You are an absolute Godsend. If you're not working in engineering or hard science, those fields are poorer for your absence.

Thanks for reading, and especially if you've got any ideas/advice you can pass on.
 

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I just completed (or thought I had) the longest, most drawn-out project I've ever undertaken. It started out with trying to determine if something in the wiring was causing P0335 (crankshaft position sensor) and P0727 (engine speed sensor). It turned into a marathon of:

R&R the CCV and associated tubes/hoses
Remove and clean TB
Remove and clean ICV
Inspect and test DISA
Remove intake manifold
Replace intake manifold gasket
Remove and replace oil filter housing gasket
New Serpentine Belt
New PS Reservoir and low-pressure hoses
A LOT of engine cleaning
Test for continuity of wiring (all the wiring checked out, and I've already replaced the CKP, so I guess it's either the sensor deep in the tranny or the ecu)

Oh, yeah: it's an '00 (11/99) 528iT automatic; motor variant is the M52TU. The tranny is the asr360, I believe.

Before, the motor would eventually start, even with the P0335 and P0727 codes. You just had to try several times and let it turn over for a long while each attempt.

Now, however, after 20-30 seconds of engaging the starter, right about when the motor would usually fire up, the motor begins making a violent snapping or striking noise.

I've done this twice, and each time halted the moment the noise begins. I can't figure where it might be coming from; it sounds forward of the starter, but not the starter itself...maybe?

Some Considerations:

1) At first I was terrified that that something hard and unyielding had fallen into the intake while it was off and I didn't notice. But the sound only occurs after 20-30 seconds of engaging the starter. If something was getting chewed up in the valves, wouldn't it be heard immediately?

2) With the manifold completely removed, there were a lot of connections, electrical, vacuum and fuel to manage. I'm confident that I've gotten these right: after all, I had to re-remove it 3 times to correct mismatched connections.

3) Prior to removing the fuel lines, I followed the Bentley's suggestion of blowing compressed air through the schrader valve. I think at some point I heard it gurgle back to the fuel tank. Too much? It sure was nice being able to remove fuel lines without spilling a drop of gas.

4)

5) Whatever it is, it's not generating any new codes. I'm working on getting a copy of DIS up and running, but I've tried before and never been successful, so we'll see.

Any ideas on what the noise could be? If someone thinks it might help, I can try to make an audio file or a video and host it.

This is killing me. I haven't driven the car since before Christmas, and I've used up almost every favor I could call in to borrow/beg a ride from others.

If you've made it this far, I'd really really like to thank so many of you for sharing your knowledge and experience. Especially cnn and Graham, and of course...

Bluebee. You are an absolute Godsend. If you're not working in engineering or hard science, those fields are poorer for your absence.

Thanks for reading, and especially if you've got any ideas/advice you can pass on.
I suppose if it were me, I'd have tossed in the towel early on and bought new & genuine CMP and CKP sensors.

Could the snapping noise possibly be due to oil not circulating enough? Or a stripped starter gear?
 

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Discussion Starter · #3 ·
I suppose if it were me, I'd have tossed in the towel early on and bought new & genuine CMP and CKP sensors.

Could the snapping noise possibly be due to oil not circulating enough? Or a stripped starter gear?
The CKP is new; it's the first thing I tried. My best guess now is the ECU or the output speed sensor in the atf pan.

The noise would only come after engaging the starter for 30 seconds or more, makes me think that maybe it's just from running it that long. So I don't crank it that long anymore.

But, now the darn thing won't start at all. Codes don't even pop up. The fuel rail is pressurizing, I guess the next step is to check for spark, then maybe the injector solenoids.

FWIW, this all started when I hit the rev limiter in sport mode and didn't realize it. Getting into the guts of the thing, I also discovered that the contact to the Alternator was loose. I wonder if this gave the ecu or trans sensors a jolt and fried them.

Thanks for the response, pleiades. Even though I'd already tried the CKP, just writing all this stuff out helps to organize thoughts and brainstorm ideas.
 

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I hope you are keeping the battery charged through all this.

I'm not that clued into what could be going on here; I'm mainly posting to keep your thread near the top until someone with smarts takes notice and steps in.

As to the camshaft sensors, I believe you can actually swap them (intake < > exhaust) to see if the fault code follows the sensor. Whatever sensors you buy, stay BMW; aftermarkets are known to fail early if they work at all.

Oh yeah..... with all that cranking and no firing, your plugs could be fouled by now.
 

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The really loud solenoid snapping means you killed the battery. I know it doesnt sound like a dead battery but it most likely is. Any other car i have ever had the motor just turns over slowly when the battery is dieing, not this one.. Apparently on this car there is a low voltage cutoff of some sort.

I killed mine trying to adjust a new fcp window regulator that was bad. I couldnt figure what the noise was either.
 
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