SLOVED!!! ANY Ideas?? Spark / Ignition Cutting out

[mucoyekul87ETA]

I am going to try and source a known good DME for mine as well, but I am so baffled that I am still not convinced about where/why the issue arises. As I said, after using a (borrowed) good DME, the normal driving cutting out seems to have gone away, but still not sure I trust it. However, I am certain that the good DME fixes the cutting out under load @4000rpm. I'm going drive with the old DME that I had minor problems with before and see if the cutting out (the mini cut-outs) comes back.

You sound like me, I have a great 325 that never has any running issues, but right now I am battling a no-start issue with her! Which could be DME related as well. Too bad they are different DME's it would make testing and sourcing computers much less of a hassle.

[mucoyekul87ETA]

I've now put in a known good and working DME in, all problems have gone by the wayside...

[ct3155]

Ok so I finally switched to a good known working dme. Still no luck. Hard to start.. Have to give it a decent amount of gas petal to run the rpms up high enough to keep it holding on while it's cutting out with the check engine light flashing still.... That's what's so Weird. That light flashing while it's running like crap. Then the light turns out for good and it will settle out... Any more ideas??

[jlevie]

Been there, done that. I chased the same kind of problem on my first & second race cars for over a year before solving it, though my problem was more intermittent. During that time everything in the engine management system was changed at least twice and the engine anc car body changed once after the first car was wrecked. Ultimately I found the problem by watching a battery powered o-scope monitoring the CPS input to the DME while a helper drove the car. When the wave form distorted, the cut-out occurred. Changing the CPS and running the same test had no affect, so it had to be the engine harness. The fourth used harness (I'd already changed the harness once) I tried was the winner. Well until until it suffered an internal hemorrhage six months later that took out the coolant temp sensor signals, which was replaced with a brand new harness from BMW.

For clarification on this problem, was the harness a new part from BMW? Have you tried a different new BMW CPS? When changing the CPS was it's cable routed through the plastic wire chase behind the water pump pulley or over the top of the head where the water pump pulley can't abrade it?

[ct3155]

Yes sir, the harness was a new one from BMW. Like 700 dollars or something crazy. The CPS is also a new BMW one with the wire ran over the head... I cracked the little plastic wire protector. So I ran all the wire over, away from any damaging pulleys.

I really feel like it isn't a CPS or dme anymore. And I can't seem to find any other wire issue.. But the problem deff has to be electrical.

Thanks so much for trying to help me out though. I appreciate all the input!

[ct3155]

Any one have any more ideas? How can this problem be so hidden???? Still have made no progress...

Still will cut out with flashing lights when accelerating... But only when I let off the gas to shift... Does it have soomething to do with returning to idle??

Also still wont start on first attempt.. Needs gas petal to rev up high enough to recover from loss of spark. And still flashes CEL the whole time, until it settles.

[FLG]

Idk how I missed it in the previous convo we had but noticed you have an aftermarket sensor, you said you new cps is black plastic? I had problems with those sensors countless times. Do you have a known good oem sensor you can test with?

Sent from my SCH-I545 using Tapatalk 2

[ct3155]

Correct my new sensor is all black plastic. I did put an all metal one in that ohmed out fine... But I guess I cannot 100% say I know that it's 100% perfect. I know they can ohm fine and be bad still. I thought all the new ones were black plastic??? Can you still get the metal ones somewhere?

Your biggest thought on this problem still CPS?

[FLG]

Yes, from BMW

The plastic ones are aftermarket usually facet

Also I know you checked the c101 and replaced the engine harness, have you pulled back the rubber covers on the connector on the body side to check for corrosion or wiring issues?
Sent from my SCH-I545 using Tapatalk 2

[ct3155]

Can idle switch cause any of this?? Only reason I ask is because the idle rpm seems to have so much to do with it... Like it doesn't wanna start.... It pulls great in every gear until I let off the gas to shift (hense putting it in idle position)... Seems so related to idle. Or maybe I'm just going crazy thinking too hard... Would anyone have a list of known things to check on this spark cutting out? Other than what Bentley says? Cause I feel I had eliminated all their causes for trouble... This is crazy frustrating.

[FLG]

No, a bad idle switch could cause issues but not in the way your car is behaving. The tach is dropping off still correct?

Sent from my SCH-I545 using Tapatalk 2

[ct3155]

Yes, from BMW

The plastic ones are aftermarket usually facet

Also I know you checked the c101 and replaced the engine harness, have you pulled back the rubber covers on the connector on the body side to check for corrosion or wiring issues?
Sent from my SCH-I545 using Tapatalk 2

Yessir I pulled the boot back and visibly saw no problems. Moved all the wires around and they seemed tight in the connector. I don't really know what else to look for there.

[ct3155]

Yes tach most deff drops. Pretty much points CPS huh? Any "body" wiring harness crap that could be messing with CPS or crank signal? Any thing under the colum and what not?

[FLG]

Yes tach most deff drops. Pretty much points CPS huh? Any "body" wiring harness crap that could be messing with CPS or crank signal? Any thing under the colum and what not?

No, not that I know of. Signal. Should just go thru the harness into the dme. Can you replicate the symptoms exactly with different cps 's?

Sent from my SCH-I545 using Tapatalk 2

[ct3155]

FLG, I super appreciate your willingness to help a brother out. You rock man!! If you were closer I'd definitely get you beer and pizza or something. Hahahaha!