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-   -   2000 740i Fires, revs to 2k and dies; No Codes. (http://www.bimmerfest.com/forums/showthread.php?t=666492)

kupplung 12-27-2012 07:15 PM

2000 740i Fires, revs to 2k and dies; No Codes.
 
Hi all, new poster and former lurker here, wondering if anyone has any ideas on this one. The title says it all, but I will give the full story here as well. Any help is greatly appreciated.

I picked this car up as a no-start. I was told it had bad timing guides. It was exhibiting roughly the same symptoms it is now, with the addition of the timing chain noise. It starts, revs up to about 2k RPM, and then dies. It's smokey. First thing I did was replace the fuel pump and filter, and pressure at the rail is at the high end of spec (53 psi). The car fires -- there is fuel and spark. I got around 100 psi of compression all the way around on a dry test on a cold engine. There are no codes in INPA. It should start, right? Why won't it?

I tore down the motor and replaced the head gaskets and other seals, and replaced the timing guides. I put some oil down the bore during reassembly.

I did not disassemble the intake manifold. I just replaced the orange seals underneath that mate against the heads. Also, two of the metal sleeve seals underneath fell out. I didn't know what they were at the time, so they are still out ("spare parts").

It also might be worth noting that I deleted the engine adaptation values in INPA before I did all the work (d'oh).

I cleaned the MAF. Unplugging it made no difference (possibly because there are no adaptation values for the DME to fall back on, because I cleared them.) There was a small tear in the intake boot, which I was able to cleanly plug up with bumper repair epoxy -- to no effect.

I am lost. Help? When I get a chance, my next idea is to reseal the intake manifold and boot / MAF parts, and replace the crankcase ventilation valve and inspect / reseal the pipe. I am also considering a clogged cat; I'm going to try starting it with the upstream o2 sensors unplugged.

Also, how should I be cranking this thing? How long? Gas pedal down?

:dunno:

Thanks in advance. Happy new year to all.

BMWFatherFigure 12-28-2012 07:35 AM

Blocked cats or blocked fuel filter - first guesses.

bluebee 12-29-2012 10:14 PM

Quote:

Originally Posted by BMWFatherFigure (Post 7275206)
Blocked cats or blocked fuel filter - first guesses.

I can't imagine those symptoms without a pending code at the very least!

Are you _sure_ there are no pending codes?
- Cheapest CAN OBDII scanner on the net that reads DTCs, pending codes, & clears codes

However, if it's the cats, this might help (let us know in those threads if it works):
- How to remove & replace a catalytic converter (1) & how to fix rattling cat shields (1) & BMW P0420 codes related to cats (1) (2) (3) & cat autopsy photos (1) & what kills cats (1) & an EPA fact sheet on catalytic converter warranties (1)

joyism5 12-30-2012 06:27 AM

Does it revs by herself or when you are pushing the gas dies at 2k?

If it revs by herself I would suspect a huge vacuum leak somewhere.

If it dies when you push the gas I would suspect fuel filter as well, but if you changed that I will go with fuel pressure regulator. Since you changed the fuel filter, that should take care of the regulator as well, but make sure you have the vacuum tube in good shape. Remove the intake elbow from throttle body, have somebody start the engine and push the gas pedal while you are spraying some contact cleaner in the intake. If there's any noticeable change I would go with the fuel starvation route.

It's weird you don't have any codes, but I guess the reason is that for most of the codes to be stored, the engine has to do a few complete cycles.

BMW 3-SERIES 01-10-2013 02:32 AM

If its like my video, its your cam-position sensors

http://www.youtube.com/watch?v=sq0ghqCMQXU

kupplung 01-11-2013 10:33 AM

Thanks so much for the replies, this is all extremely helpful. I unplugged the upstream o2 sensors, no change. I replaced the CCV and seated the manifold oh so carefully, no change. Replaced the crankshaft position sensor, no change. (Throwing parts at it.)

Behavior is EXACTLY like in BMW3-Series' video. It will crank and not start, or crank and fire to about 750RPM with no gas pedal. If I hold the gas pedal all the way down, it will rev to ~2K RPM and dies.

I guess it is possible that a bad CPS (crank or cam) is giving a weak signal (but not bad enough to throw a code) and the spark and injector signals from the DME are intermittent. At this point I am wishing I could afford an oscilloscope. There are some on CL for around $500. I can spend that much throwing parts at it pretty easily! However, I think the intermittent ignition theory is quite plausible, because I was never able to get the car to stay running on carb cleaner.

I also agree with Joyism and BMWFatherFigure that it sounds like fuel starvation. But the fuel pressure checked out, and I already replaced the pump and filter, so I was starting to think the fuel could be very old -- I have no way of knowing how long the car was sitting. Today I was planning on draining the tank and putting in fresh fuel. But I don't know if that's consistent with that I couldn't get it to run on carb cleaner.

Gosh. It's just like the video. I wonder if I should just order up the CPSs...

Also, about the codes. I am using INPA, and I can get the codes. I had a downstream o2 sensor codes and a thermostat code, but I fixed them. Was the car in the video throwing codes?

BMW 3-SERIES 01-12-2013 01:11 PM

Its not fuel stravation. Easy way to check that is pressing the valve on the fuel rail. If it shoots out gas, your fine. I replaced my fuel pump thinking it was bad and it wasn't. As soon as I replaced my CPS it started.

kupplung 01-12-2013 02:45 PM

Fresh fuel didn't fix it, but it really does sound noticeably better when it's firing, like sharper. Still dies.

I went ahead and ordered two new OEM camshaft position sensors, and a new OEM crankshaft position sensor. They'll be here Monday. I hope this fixes it, because I'm out of ideas. Next I really will need an oscilloscope.

BMW3-SERIES, you didn't say whether or not your car was throwing codes.

kupplung 01-16-2013 04:35 PM

New OEM crankshaft and camshaft position sensors, and it fired right up and ran like a dream.

joyism5 01-17-2013 04:37 AM

Quote:

Originally Posted by kupplung (Post 7318695)
New OEM crankshaft and camshaft position sensors, and it fired right up and ran like a dream.

Nice! :thumbup::clap:


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