M42-318is...motor cut out

[e30nut]

Gruppe:

More Perils of Pauline for my DD 91 e30 318is (M42). This car is definitely of the fairer sex.

Driving down the highway this AM, 65mph (honest!), engine cuts off, no noticeable noises, all the instrument lights come on. Felt similar to a timing belt failure, but of course the M42 has a chain. Fortunately, no traffic and I have enough speed to get down the exit ramp and wait for a tow. Stereo is still playing. I have coffee to drink.

Background:
Engine has been flipping a faulty O2 sensor code, off and on for a month. Running up the revs usually clears the Check Engine light on the dash. I recently cleared the codes with my Peake tool. I suspect mixture is rich. Need to put the Exhaust Gas Analyzer back on it and fiddle with the AFM settings. Cat (DEC) and O2 sensor (Bosch) are both recently replaced. O2 sensor voltage fluctuates as it should, and responds to throttle.  Charging system has been fine. Battery is good. Engine is recently rebuilt (new head, intake and injector seals) and has been pulling strong. Getting 28 mpg combined. All healthy signs. Mystery coolant consumption. Fixed a bad thermostat housing gasket. No oil in coolant or coolant in oil AFAICT. Hopefully that's not this issue, just background.

Postmortem:
-Starter spins, but does not engage.
-I have fuel at the rail. Upon turning the key to ignition, I cannot hear the in-tank pump anymore...it's been noisy for 1.5 yrs.
-Fusible link is OK on the battery cable (ECU has power).
-Silly me disconnected the battery to check the fusible link and that cleared any ECU fault codes (right?). Peake tool shows no codes (grr).

Questions:
-What could a faulty starter (solenoid most likely) have to do with the engine cutting out while underway? nothing, right?
-I suspect an electrical issue, but will not know until I R&R the starter. Luckily I have one from the old broke motor to put in there. I'm good at taking the intake apart!
-Main pump is still supplying fuel to the rail, although I don't have a pressure gauge, the in-tank pump is really there to keep the main pump primed under higher flowrates, right?

Hopefully, starter will be out this afternoon, if I choose not to watch the Redskins Game...

I've cross-posted this to the e30 yahoo gruppe as well, because I don't think this is an M42 specific issue...

cheers!
John Grills
National Capital Chapter BMWCCA
98 M3/4
91 318is
88 M3 (which is now pushed into DD service, things could be worse...it could be snowing)

[Vladi]

Hm, first thing i'd check after you fix the starter are the coils.
No, the starter has nothing to do with the engine cutting out.
I had the same mistery coolant loss until i discovered a tiny leak at the radiator, the water evaporated before it would fall down. It would loose about 200ml of coolant/300km.
So, measure the coils. :rolleyes:

[eric ^__^]

sounds like you're on your way to tracking the problem down (not that I have the faintest idea why the motor would just die like that) so I just want to say

'88 M3

[e30nut]

yeah, I decided to watch football and wait until tomorrow so I can at least go to the stealer for parts if need be...

I've been advised to check the Main relay that basically controls the ECU....this has symptoms of an ECU cut off (all the instrument lights going on)...thus my thought about the fusible link...the starter all of a sudden not engaging is just bizarre...

It ain't all bad that I'm forced to drive the M3 tho...thanks!

I really like BOTH of my e30s for different reasons, but mainly their light weight...and the M42 currently has a better suspension setup...always tinkering.

cheers!

[e30nut]

Hm, first thing i'd check after you fix the starter are the coils.

brand new fancy high performance BavAuto Coils....I saved the old ones too being a pack rat.

No, the starter has nothing to do with the engine cutting out.

agreed, that just bizarre

I had the same mystery coolant loss until i discovered a tiny leak at the radiator, the water evaporated before it would fall down. It would loose about 200ml of coolant/300km.

thanks for the tip!

So, measure the coils. :rolleyes:

straight resistant measurement?

[Vladi]

Check the pdf for coil measurement. But before this check the main relay and even the crank sensor. :rolleyes:

[e30nut]

Coils check out OK

Buying relays today...all three of those buggers on the firewall...Main (white), O2 Sensor Heater (Blue), Fuel Pump (Orange)

hey guess what! the O2 Heater Relay may be causing the O2 sensor error code to flip....it IS intermittent, like a failing relay tends to be!

I've owned 3 other e30's and never replaced any of these relays before (to include a 267k mi 88 325iX)...guess I was living on borrowed time. Perhaps these are preventative maintenance items? I've heard others suggest this. I think I'm going to suck it up and buy a new fuel pump too...this is my DD, so I'd prefer no more surprises.

cheers!

[e30nut]

Vladi,

crank sensor shows only 528 ohms, supposed to be 1280! guess that's it...the DME will not fire the engine w/o a proper signal from this sensor. I have a spare that I will swap in whenever it stops raining!

cheers!

[e30nut]

OK,
Finally stopped raining. So, all new relays. Still no buzz from the NEW fuel pump (now I have a spare...damn). So I start detailed troubleshooting...section 130-7 of the Bentley Manual

Main Relay: Ignition On, No switched ground from DME on terminal 85
Fuel Pump Relay: Ignition Off, no 12v on terminal 30,
Ignition On, No switched ground from DME on terminal 85

Bad DME, right?

I guess DME failure can happen at any time, right? I just thought it odd to happen while underway.

[Vladi]

If you have no spark, you have no fuel. Get another DME and test...who knows. :confused: Also make sure all the ground connections are where they should be (broken wire, etc.)

[RED IS 91]

Vladi,

crank sensor shows only 528 ohms, supposed to be 1280! guess that's it...the DME will not fire the engine w/o a proper signal from this sensor. I have a spare that I will swap in whenever it stops raining!

cheers!

The bentley manual is incorrect ! The correct ohms for crank sensor is 500 -550  . the camshaft sensor is around  1280.
Your crank sensor is close to spec.

I found this out the hard way.

[e30nut]

As suggested, crank sensor(s) are fine.

Just got a replacement DME in there...still no start. Still no power to the new fuel pump (new relays too). I even jumpered across the fuseable link, which looked fine anyway.

I guess next is to test for power on the DME connector. Not sure of any other way to see if the DME is even powering on or not.

I have spark at the plugs, does that indicate DME function? I assume DME fires up the coils, right?

Physical wiring checks are a possibility....but the car was running just fine before it cut out on a smooth highway! Chassis ground is fine, as my instruments are powering on.

The starter is still making that whirring sound. The fan is spinning under start, but no cranking. I swapped the starter with my spare...same sounds from both starters, so it's not likely a starter solenoid issue. e30 M42 engine has no knock sensors (on the flywheel), so they can't be failing

Help! I'm at whit's end on this one!

[e30nut]

OK,
I can make the pump run by jumpering across the fuel relay, so wiring
is good. I tried cranking while jumpered, still no start. just goes
whrrrrrrrr. Fan is spinning, so I assume crank is moving...right?

I still have no signal from pin 1 on the DME to pin 85 of the fuel
pump relay. The DME pulls pin 85 to ground to allow the Fuel Relay to
power up the pump.

I see only 2 relays in the driver's foot well. One is the flasher
relay, up on the steering column, 3 pin (49, 49a,31). The other is a
4-pin (15,31,L,S) with a small mounting clip on it. It's the larger of
the 2. It's labeled "Gurt Zeitgerat" which lit. translated means
"seatbelt timer"... the gong control for the seat belts.

I have a simple 9 button e30 OBC, so no CODE feature, right? This is
getting very frustrating. Do I even HAVE an OBC relay on this car? I
can't find mention of one anywhere...

Same symptoms w/2 different DMEs now...crank and cam sensors are in
spec. Same whrring sound w/2 different starters, both worked fine
prior to the engine cutting out...going on 2 weeks now! The Gremlins
are ready to jump in there!

r/jpg

--- In E30@yahoogroups.com, arma defuego wrote:
>
> if there is no power at the main relay then it could be the OBC
relay in the driver's footwell.
>
> Check for main power at the main relay.
> If power there switch on the car and check for power at the fuel
relay.
> If no power there check at the OBC relay.
>
> not much point in swapping parts elsewhere until you can get power
at the fuel pump.
>
> Gary Derian wrote:
> I don't have a 318 ETM but in the 325 the coil gets power
directly from the
> ignition switch, through the OBC code relay. If you're getting
spark, the
> DME is switching the coil primary, which means it is getting power to
> operate.
> Gary Derian

[RED IS 91]

I have a simple 9 button e30 OBC, so no CODE feature, right?


You've got to do the stomp to get the codes ..................Please read

http://www.pelicanparts.com/BMW/techarticles/JF-Tech/E30_E36_On_Board_Diagnostics%20.htm

[e30nut]

I've swapped the DME in and out since the motor cut out....does the DME save Codes w/o power?

I'll give the stomp test a go...to be honest, I never knew you could get that deep into the code diagnostics...the Peake tool is quite limited in this regard. I used that 1st, and nothing showed up...

The Code relay I was referring to is on e36 models as part of the OBC...I do not have one on this car, only the simple e30 OBC.

cheers!