Crank, crank, crank, crank - but no start

[knunger]

This is an '83 635csi running motronic 1.0.  It has an 011 ecu
The reference and speed sensors ohm out properly according to Bentley
Fuel pump is putting 45psi to the rail
Cranks forever
We swapped out a known good ECU - no help.
coil has power in start and run
injectors have 12v - BUT THEY ARE NOT FIRING.  Verified via noid light and stethoscope

I have an old BMW hand helping me and he asked for a pin-out schematic for the 35 pin 011 ECU.  I found a few on the internets, but, they are not identical.  But, they all show at least one pin that is continuous +12 volt.  He found a couple that have 12 V when the key is in run, but none when the key is off.  Does this matter??

Any suggestions as what to try next??

TIA

[turbodan]

Speed and reference sensors can test good and still not work. There are other failure modes aside from and open or short circuit. Seen it myself. 

If the injectors and coil have power and it's not grounding the injectors, it is most likely that you need to replace the speed and reference sensors. 

[kojo96]

Speed and reference sensors can test good and still not work. There are other failure modes aside from and open or short circuit. Seen it myself. 

If the injectors and coil have power and it's not grounding the injectors, it is most likely that you need to replace the speed and reference sensors. 

Or,... they got reversed? I know you had that car way apart...

[Mike W.]

Adding to Dan's remarks, it's even possible the tab came off the flywheel. Very rare for a M/T, I believe you can check for that by looking for a voltage spike while cranking, or for that matter the flywheel tooth counter too.

I suspect, but don't know, that the 011 ECU is similar to the US market 008. Same era, Motronic 1.0, M30, etc, without the O2 input of course. Not a definitive statement, but I can't find anyplace on the 008 schematic where unswitched 12V goes to the ECU. Not even on the 059 which is Motronic 1.0a, meaning adaptive. Nor can I recall any posts about it in the past.

Not sure what difference it would make, but I'd check for spark also, just in case you have one but not the other. Might narrow things down a bit. And of course, what, if anything has been done to it recently, even if seemingly unrelated. Or had it been running just fine, nothing besided putting gas in it and then one day it wouldn't start?

[Mike W.]

Or,... they got reversed? I know you had that car way apart...

Definitely seen that one before.

[1st 5er]

Speed and reference sensors can test good and still not work. There are other failure modes aside from and open or short circuit. Seen it myself. 
 

Same here. 

Also I've had them test good but not making good connection at the harness. 

[knunger]

Speed and reference sensors can test good and still not work. There are other failure modes aside from and open or short circuit. Seen it myself. 

If the injectors and coil have power and it's not grounding the injectors, it is most likely that you need to replace the speed and reference sensors. 

Today I will pull them from the bellhousing, clean them and see if that helps. If not, I guess I'll start throwing parts at it.  But I have a question:
RealOEM shows "pulse generator", p/n 1214 1 708 619, and that I need 2 of them.  Is that correct??

Or,... they got reversed? I know you had that car way apart..


 

I tried reversing them, no go

Adding to Dan's remarks, it's even possible the tab came off the flywheel. Very rare for a M/T, I believe you can check for that by looking for a voltage spike while cranking, or for that matter the flywheel tooth counter too.

I suspect, but don't know, that the 011 ECU is similar to the US market 008. Same era, Motronic 1.0, M30, etc, without the O2 input of course. Not a definitive statement, but I can't find anyplace on the 008 schematic where unswitched 12V goes to the ECU. Not even on the 059 which is Motronic 1.0a, meaning adaptive. Nor can I recall any posts about it in the past.

Not sure what difference it would make, but I'd check for spark also, just in case you have one but not the other. Might narrow things down a bit. And of course, what, if anything has been done to it recently, even if seemingly unrelated. Or had it been running just fine, nothing besided putting gas in it and then one day it wouldn't start?

 

 

I do get a voltage spike when cranking.
Thanks re: unswitched voltage.
It does fire briefly when I squirt in starter fluid, so, yes there is spark.
It was hard to start the last 5 or 6 times I drove it. I am in the final stages of restoring it but health issues have put it on the back burner: the last time I started it was probably a year ago...
I'll let y'all know what happens, thanks all for the input no matter what happens...

[Mike W.]

But I have a question:
RealOEM shows "pulse generator", p/n 1214 1 708 619, and that I need 2 of them.  Is that correct??

Yes, technically one is called the reference sensor and the other is the speed sensor. One reads the tab on the flywheel to tell the ECU where TDC is, the other counts flywheel teeth telling the ECU when to spark and when to fire the injectors.

Since you have spark, and I'd double check it, that indicates that the sensors are good. I'd dig into the wiring harness at the ECU, find the wires going to the injectors and check that. It might just be a wiring issue. Remember, the injectors have 12V going to them once the ignition is on, passing thru the coil of the injector it will show 12V on both sides of the injector. The ECU grounds the circuit when it fires the injector.

[knunger]

Well, I thought I had spark because I thought it fired temporarily when I squirted in a bunch of starter fluid. But, when rechecking with a timing gun, nothing.
I replaced the ref and speed sensors with the ones from my e28, no help.
I did all of the electrical tests recommended by Bentley to the ECU harness (Sec 7, pg 33).
Also did the coil tests.  Dist cap and rotor have less than 100 miles.  According to Bentley, all of this says my ECU, actually BOTH of my ECUs are bad.

Any other suggestions as to what I should try?

What would happen if I swapped the 059 ECU from my e28?  It has high impedance injectors and the 011 ECU in my e24  are low impedance.

A penny for your thoughts and a case of beer if they work!! 
 

[Aldo525]

Well, I thought I had spark because I thought it fired temporarily when I squirted in a bunch of starter fluid. But, when rechecking with a timing gun, nothing.
I replaced the ref and speed sensors with the ones from my e28, no help.
I did all of the electrical tests recommended by Bentley to the ECU harness (Sec 7, pg 33).
Also did the coil tests.  Dist cap and rotor have less than 100 miles.  According to Bentley, all of this says my ECU, actually BOTH of my ECUs are bad.

Any other suggestions as to what I should try?

What would happen if I swapped the 059 ECU from my e28?  It has high impedance injectors and the 011 ECU in my e24  are low impedance.

A penny for your thoughts and a case of beer if they work!! 



 

 

Something as simple as the Motronic Relay next to the fuse box???....noted your car is 83' euro, they have that relay.

See this thread from another forum (e24)
https://www.bimmerforums.com/forum/show ... ng-Systems

[Mike W.]

I'm not sure I've seen main relay mentioned. It's a unique relay on the car, 5 pin but has to be 87/87 or 87/87b. If it's got an 87a pin on it, it's the wrong one and the car won't run. It should click when you turn the ignition on. Or jumper it just for shits and giggles, a Y jumper going to 30, 87 and 87.

Power to turn on the main relay, which in turn powers both the fuel and ignition systems, comes from the ignition switch, to the OBC relay box, to the main relay. Key on, relay out, you should have power at terminal 86 of the main relay socket, probably a small green wire. That turns the main relay on. Terminal 85 should go directly to ground, unswitched. I'm reading this off a US spec '83 E24 wiring diagram, but I suspect that part is the same.

As far as running your low impedance injectors off an 059, they will kill it, but not right away. A friend ran one for some time, like I think a couple of years of light driving before it died. I'm not sure exactly what parts he had in there, it was on a Bavaria and I think he might have used early, 533, parts initially, then converted to later 1.0a. Just how much he did or didn't change I'm uncertain.

You also mentioned using a timing light to check for spark. I'll pull the spark plug lead off the dist cap, get it close to ground and crank it to look for spark. I would want to see a real spark, not just hope a signal is read.

[knunger]

main relay is good.  Its an 87/87 and works in my e28.  Trust me, there is no spark.

Man, I hate to swap the 059 for the 011 if there is a chance I'll fry it and need 2 $450 Ecus instead of one...

I'll post a thread asking to borrow an 011 and see what happens

Thanks Mike.  Appreciate your efforts

[Ray in Phoenix]

Please give me a call,
I am running a 008 in My E24 right now.
Ray in Phoenix

[Ray in Phoenix]

Please give me a call,
I am running a 008 in My E24 right now.
Ray in PhoenixTop

 

[Reno]

Hi from Belgium!
I will try to do my best at English.
Not sure if you already checked,  but if you get any air leaks in the intake system, it might lead to the symptoms you describe.
check the air hoses from the intake manifold (there are at least two bigger ones that lead to the mastervac brake servo, they are often cracked by the heat)
Also check the thinner ones that go to the other upper side (passenger) of the intake manifold.
Of course make sure all contacts in the airflow mass sensor connecter are clean and well plugged in the socket. Check your throttle body sensor connector, underneath the airflow mass sensor. I could also think of the ”pressure capsules” ( I don’t know the right term for them), but I still have to see the first one fail on me.

if none of the above solves the issue, check the fuel pump, fuel pump relay, fuel filter ( which might get clogged), fuel line, sparkplug wiring (if cracked --->trash), sparkplug caps (they have a specific resistance , though it’s also ultra rare they would fail), ignition coil + connections, sparkplugs (fouled), rotor and rotor cap (contacts must be clean and not damaged), and finally........ alarm system, if there is one, and of course the valve train adjustment, but this one is pretty obvious, as is the presence of fuel in the tank

Not sure if this will help, but that air leak stuff is something I would make sure is not the culprit first. When there is one -----> no start, or at best just a one second firing followed by silence...

You might want to insist à bit on the gas pedal after you unplugged and reconnected those airhoses when trying to start, until the sytem re-pressurized (just a few seconds though)

Edit Oh I forgot to mention, oil cap and oil gauge MUST be shut and tight, though it might not completely shut the engine off it would drastically reduce the idle rpm.

All my best wishes from over the pond, and good luck with your baby!

This is my first post here, I hope I didn’t do anything wrong. THANK YOU ALL for your understanding. 

Reno