Running only one bank after...

[cartoonz]

My testing confirms that the DME 2 electrical path is not working. But where in the path is the problem?

Your "testing" confirms that the side of the engine corresponding to DME#2 isn't working... don't confuse yourself, it isn't necessarily anything to do with the DME.

If you've been flipping the wiring harness up and down to work on the top end of your motor, you could have a broken wire inside the loom too.. .after 20yrs, those are more than brittle... far more likely than a wire suddenly "going bad" anywhere near the DME box...

Test continuity from each sensor to the DME plug (use the schematics). Test the wires to your coil on that side from the DME plug as well. That will get you headed in the right direction.

It's also usually helpful to think about exactly what area of the car you were working on between the last time it ran correctly and when it started acting up.... chances are more likely than not that is the area where something got knocked loose or broke. While you were experimenting with the Pentosin fountain technique, is it possible you physically disturbed something or flooded something with Pentosin that should be kept dry?

[ChrisFuture8]

I had the same exact thing happen to me with my 91 850.i just finished swappin
Out my cylinder heads.i used the the starter motor to check my cam timing,i forgot to
Re connect my driver side coil lead wires and they grounded to the chasis when i turned
The ignition switch on and it fried my passenger side dme.but before i figuered it out i swapped
Out everything.dme's coils cps sensors maf sensors cyl id sensors fuel pumps even changed
the eng.harness.put in two different dme' car came back to life.took me a couple
of weeks to figure that one out...hope that helps

Hi 8isenuff. Thanks for sharing your experience. I don't have spare DMEs to try. What I did discover just a moment ago was the driver's side actually fire up and run for probably less than 20 seconds.

I disconnected the CPS and cylinder ID sensor on the passenger side but left the driver's side connected. I had my significant other started the car while I stood in the rear of the car looking at the exhaust. This was around 11:45pm so it's nice and chilly outside and easy to see smoke. With the passenger side disconnected and her starting the engine, I did see smoke come out of the driver's side exhaust only. The engine died shortly after.

When I reconnected the CPS and cylinder ID sensors to the passenger's side and had the engine restarted, the car continues to run and I see smoke from both exhaust tips at moment of startup. A few seconds later, it's only the passenger's side that's still producing exhaust.

At this point, it looks like the CPS for the driver's side may be faulty like most have eluded to. I'm going to take it out and clean up the tip and see if that helps.

Thanks,

Chris

[cartoonz]

if you switch the DME's and the problem does not switch banks, it is NOT the DME.
Seriously, you're over thinking this...

[ChrisFuture8]

It's also usually helpful to think about exactly what area of the car you were working on between the last time it ran correctly and when it started acting up.... chances are more likely than not that is the area where something got knocked loose or broke. While you were experimenting with the Pentosin fountain technique, is it possible you physically disturbed something or flooded something with Pentosin that should be kept dry?

Hi Cartoonz,

Unfortunately, I was all over the engine. It wasn't just to the driver's side of the engine only. I had the radiator out and replaced hoses, pulleys and pulley shocks as well. I also had the distributors removed and out of the way too.

I had a automotive stethoscope and pointed the tip to the fuel injector rails. I can certainly hear the passenger side injectors running and the driver's side silent. I also listened to the fuel pump(s) in the rear and definitely they are running. The lines are pressurized.

I will try to wipe dry everything one more time. Just a wild question, would leaking intake manifolds cause one of the banks not to run? I don't think the intake manifolds have vacuum leak but just wondering.

Thanks,

Chris

[cartoonz]

I'd be focusing on the continuity checks I mentioned earlier if it were me...

[ChrisFuture8]

A little update on the situation.

So I continue to forge forward but have made no progress.

I had another person start the motor while I use a stethoscope and listened to the driver's fuel injection rail.

At the start of the engine, the driver's side fuel injectors fire and exhaust comes out at the pipe tip. The injectors continue to fire for another 3 seconds or so and stop.

I have checked, and checked, and checked on the driver's side and there's nothing I could find that is loose or disconnected. I pulled the plugs and the plug cables and reconnected them tightly.

I swapped the CPS cables to see if the problem follows and no, it doesn't.
So, it's not the CPS or the cylinder ID cables. Both were swapped without any differences seen.

So, Koister dropped of the GT1 diagnostic tool suite. I ran through a battery of tests and it derives to the same issue I discovered prior to using the tool: No fuel injection or fuel injectors not firing.

I pulled the error code (DME 16) and here's the results:


Diagnosis DME Fault Explanation

Effect in the event of a fault:
Injection signal is reduced to a minimum:
- no fuel injected into Cylinders 7 - 12

- EML SG does not switch to the emergency program!


################################################## ################


Possible causes of fault:

- cylinder-detection sensors or supply wires faulty

- no ignition voltage signal reaches cylinder 6 or 12

- no spark discharge at the spark plug of cylinder 6 or 12

- ignition coil faulty

- ignition output stage of DME SG faulty


Cartoonz suggested performing continuity tests from the DMEs. How do I do that or is there a procedure somewhere? I'm not sure at what point at the DME box I start at. Each DME harness has a lot of wires so I'm not sure which wire goes to the CPS sensors.

The only thing I have tried is swap out the distributor but they are practically new.

Thanks,

Chris

So after the tests result posted, could anyone possibly think of anything else I could try?

I tested spark on the driver's side and each spark plug cable is active. I pulled each cable at a time and inserted a spark plug and started the engine. Each plug fires.

I swapped the fuel injector electrical plugs from the running side to the non-running side (driver's) and started the engine. As expected, the driver's side is now running and the passenger not. Certainly, the DME2 path.

Hope these test results shed some light where someone has an idea.

Chris

[sickle44]

Continuity test is really quite simple. Basically all you are doing is attaching two test leads to either end of a wire. If you have the cool kind of continuity tester you'll get a constant beep as long as you've got the test leads on that wire, or you'll have a readout on your meter if it doesn't have the Beep function. If you don't get a beep/read out, you've got a broken wire, fix it, or better yet, replace it altogether.

[91e34M5]

Chris...do you have an update.. I don't see where you have swapped the coils...it's worth a try.

[Cup1d]

I have the same problem you have. What did you do the fix it?

[ChrisFuture8]

I have the same problem you have. What did you do the fix it?

It was a lot of things that eventually went wrong/bad during the spout of failures but at the end, replacing the engine wire harness fixed the problem for me.
Intermittent continuity issues with the wires leading to the four plugs under the oil catch (for CIDs and CPS sensors) caused some serious chasing after electronic issues and parts failures.

[TedBobo]

It was a lot of things that eventually went wrong/bad during the spout of failures but at the end, replacing the engine wire harness fixed the problem for me.
Intermittent continuity issues with the wires leading to the four plugs under the oil catch (for CIDs and CPS sensors) caused some serious chasing after electronic issues and parts failures.

Wow, something else to look forward to!

[peake]

It was a lot of things that eventually went wrong/bad during the spout of failures but at the end, replacing the engine wire harness fixed the problem for me.
Intermittent continuity issues with the wires leading to the four plugs under the oil catch (for CIDs and CPS sensors) caused some serious chasing after electronic issues and parts failures.

Where in the cable harness was the break placed?

I had a similar problem with my 850i-92 when the bolt terminals on the ignition coil on one side suddenly was loose. It turned off that side of the motor one day when driving. It took several weeks to find and correct.

[cartoonz]

most common area in the engine harness where wires break is in the rear, where it curves toward the ECU's... especially if the harness has been lifted over time to service the top end of the engine.
next up is at the back of the connector plugs for the crank and cam sensors.
None of them are a lot of fun to track down...