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Old 08-17-2012, 10:59 PM   #1
nny403
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E34 Crank, No Start Problem

Here's what I've got facing and I'd like some input from you folks. I've used the search function until I'm blue in the fingers and coming to my wits end.

1995 E34 525i M50 Engine 192000 Miles

Crank, no start. I have performed the following tests and replaced a lot of parts that rated failure.

Replaced crankshaft position sensor (CPS) due to Ohm reading of +1000ohms, current reading of 545Ohm which is within the specified range per updated Bentley.

No fuel being delivered to fuel rail, unable to jump points 30 and 86 at relay. Replaced relay and receiving 54lbs fuel pressure at the rail. Tested fuel pump externally and had good pumping operation when hooked to a 12V source.

Replaced DME with red label and associated EWS delete chip, and have good signal from the relay. Also replaced relay because it was inexpensive to do. I have not yet cut the wires to the unit itself, but given that fuel is being delivered I'm not thinking that would be the problem.

Tested compression and received the following dry and wet readings

Dry
Cyl 1 0 PSI
Cyl 2 135 PSI
Cyl 3 160 PSI
Cyl 4 80 PSI
Cyl 5 155 PSI
Cyl 6 160 PSI

Wet
Cyl 1 150 PSI
Cyl 2 210 PSI
Cyl 3 270 PSI
Cyl 4 180 PSI
Cyl 5 150 PSI
Cyl 6 220 PSI

I did not have a chance to perform a spark test on it yet as one of the insulators has gone loose. I will replace this and report back in. Can someone deliniate the process of a coil pack testing for spark? I'm familiar with testing for dead ones but not checking for spark. My apologies.

I can see the crank operating and accessories spinning when I have someone turn the key.

I have also performed the "stomp test" but it isn't revealing anything useful. The only repeating message I get is one short flash followed by nothing followed by a long light then it repeats.

I have also replaced the old battery because it was testing too weak (440 CCA) to correctly start and operate the car. It sits on a trickle charger with automatic shut off at night time to ensure full charge.

If it helps, I also have the following issues yet to resolve;

When trying to crank over when I brought it home the car sputtered and the MAF started smoking, the screens are melted on both ends. This will have to be replaced but aside from poor running it shouldn't affect startup.

There is a coolant leak at the air box where it vents into the intake manifold. This has been bypassed for the moment, but will eventually need to be replaced. (the air box assembly)

So that's where I'm currently at. Aside from changing the spark plugs to known good ones, and testing that I have spark what comes next?

When I change the plugs and determine that I have no spark what is the next diagnostic test I need to run?

Thanks in advance for any help you can offer, I'll answer any questions you might have as best I can.

Ken
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Old 08-23-2012, 10:30 AM   #2
Hellabad
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How about the wiring to the Crank Position Sensor?

Did you put in a brand new Crank Position Sensor?
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Old 12-21-2012, 07:17 AM   #3
e34_spangler
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I would bet fuel pump my e34 did this and its cranking hut not getting any gas you can check this by having some one hit the pump in the trunk while you crank and it'll start the car if its bad
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Old 12-25-2012, 03:27 AM   #4
BavarianAddict06
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get a long screw driver and place them on the injectors and see if they click when ur cranking.
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Old 01-05-2013, 08:56 PM   #5
k.gen04
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Check the CPS gap with a feeler gauge. Should be 1mm
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Old 01-09-2013, 02:42 AM   #6
ethrty
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usually is a CPS issue with the M50 engine. you want to get the correct ETM and find out if the two pins on the ECU plug are showing the reading, i would do this before i would carry on. I wish i could tell you the pins for you, but i only have an M70 ETM to hand, lost the links i had for my 24V E30 conversion when my old computer got stolen.

However, it isn't unknown that the MAF can cause a no start, and combined with your vacuum leak, it may just be too much for the engine to start. always best to start with a known working engine in theory before carrying on diagnostics.

my final note is the M50 does have a sophisticated enough ECU that it can store codes and can be read by a scan tool or by a BMW dealer. I personally dont believe in "the stomp test", i have read about it on the internet, and some people claim to be able to do it, but i have never been able to get that to work any and all my BMWs over the years, nor know anyone in real life thats been able to do it. I do have a Carsoft scanner though, it shows the occassional hiccup, but for $60 you cant complain

hope this helps
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Old 01-12-2013, 11:10 PM   #7
Ryann
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Put engine at TDC 1 compression stroke according to piston/cam position and verify that the crank timing marks line up. Fixed a similar issue recently when I found that the woodruff key holding the CPS tone ring to the crank in the proper position had sheared, allowing the CPS tone ring to rotate on the crank, thus delivering bad info to the DME.

There was no CEL.
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Old 01-13-2013, 07:59 AM   #8
Austin!
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Quote:
Originally Posted by Ryann View Post
Put engine at TDC 1 compression stroke according to piston/cam position and verify that the crank timing marks line up. Fixed a similar issue recently when I found that the woodruff key holding the CPS tone ring to the crank in the proper position had sheared, allowing the CPS tone ring to rotate on the crank, thus delivering bad info to the DME.

There was no CEL.
You realize what car this is, right?
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Old 01-13-2013, 11:28 AM   #9
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Yup.
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Old 01-25-2013, 12:49 AM   #10
Wanganstyle
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if you unplug the maf on a normally running car it will still run - just poorly on stupid mode. bad maf sensor may cause it to not run at all.

if you want to see if spark is happening you can spray some starter fluid on the air filter and see if the issue is fuel delivery related (lack of fuel). A engine with everything besides fuel working properly will fire up and idle on starter fluid alone
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Old 12-11-2017, 11:35 AM   #11
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Does anyone else here have the same issue that I do - when you have a car that has been a problem child and you can't seem to figure it out, but your mind never shuts off and the answer comes to you in the middle of the night for some strange reason?

My track beater S52 car has been having an issue with a rattle coming from the front cover area for a long time. This engine has been nothing but issues for me over the last two years, so I let it go and decided to drive it til it blew up. Fast forward to three weeks ago, the last time I drove this car, it just died on me. Smelled rich like the cat clogged, but that wasn't the issue. Swapped the DME, same issue. Swapped the CPS, same issue. Decided that the engine jumped time somehow (even though it still has 200 PSI on all six) and let it go. Woke up from a dead sleep at 3 AM and remembered reading this thread almost five years ago and the issue that Ryann had and what the solution ended up being. Figured it was worth a try, so I went to the shop this morning. Lo and behold, fuck-ass that rebuilt this engine years ago never torqued the front crank hub down. It was moving back and forth as it pleased, creating a crank/no start issue.

Exact same issue as Ryann had, no CEL and everything acted normal otherwise. Reassembling now...
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