760 No Start/Stall Troubleshoot Help

[podgerd]

Hi all,

So I've got a 1990 760 Turbo wagon. At first I noticed it would take a long time cranking to finally fire up, then one day it just wouldn't start, at all.

So I did the following:

- timing belt replacement (i thought maybe a tooth skipped, but nope)
- replaced crank position sensor
- oil change (just for fun)

Then I found it wasn't getting any spark. So I...

- replaced wires and plugs

Still no spark...

- I traced back and found I wasn't getting any power going to the ignition coil.

Then one day, after sitting for a couple weeks, miraculously it just started up again. Then the other day as I'm driving it just stalls. Previously the problem was just not starting, this is the first time it has stalled on me.

So...

- replaced radio suppression relay
- replaced fuel injection relay (I'd heard these were common problems and it fits the symptoms I've been having, but nothing)


SO, given that I have previously established there was no power going to the coil, does this mean it's a problem in the ignition somewhere? Now I have no idea how to continue.

I opened up the panel under the steering wheel and found an old remote starter module installed [see pic]. Could this be the problem? I just don't know anymore...

Thanks in advance for any help/advice

[Chrali]

The ignition power stage supplies power to the coil - I just replaced mine. I also suffered stalling, and long crank times.

[podgerd]

Is the ignition power stage the same as the ignition control unit? And where is it located? Thanks!

[Chrali]

On my LPT its on the NS front wing, by the radio supression relay, both are in fron of the ABS unit partially hidden by the wiring loom running over them. Theres a large connector going to it, and the stage is bolted with 2 small bolts to a heat sink. Its only approx 1 inch x 2 inches in size. Also clean the mating faces to the heat sink and use some new thermal paste when bolting it back.

[podgerd]

Thanks a lot Chrali, I took it off and cleaned the surfaces but no change so I guess I'll be buying a new one and a new coil while I'm at it. Thanks again for the help.

-rog

[bob12]

Please let us know how you get on.

[podgerd]

So I installed the new ignition module and coil but nothing changed! Still doesn't start, just cranks over and over and over.

I also ruled out the ignition switch. So the problem is somewhere between my ignition coil (the blue ignition wire) and the ignition switch (blue ignition wire). Anyone know if that wire goes into a computer anywhere or a sensor of some kind? Can I just run a new wire from the ignition switch to the coil? I'm getting fed up with this.

[Chrali]

Have you rechecked to see if you have spark?
Does it fire at all?
Is the emission light on?
Are there any fault codes to be read from the underbonnet diag box?

[podgerd]

Yes, I've rechecked for spark, still no power coming to the ignition coil. I've checked all the fuses as well as for any codes, 1-1-1 is all I get. The emission light is not on. Just turns over...

[CTCNetwork]

Hi,

Are you getting compression by any chance?

Des. . .