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

[ct3155]

SOLUTION IS POST NUMBER 70!!!!

Ok guys,

Ive run into a problem I cant solve. Its 100% ignition problem.. I've got a video for you to watch to spark ideas.

Details on car: 1988 325is with 173 dme

New this summer:

-Entire under hood engine harness / injector harness
-Miller PSIK with MAF
-plugs / cap/ rotor
-BAV AUTO wires
-Ignition coil
-crank POS sensor
-Coolant Temp sensor
-Injectors
-O2 sensor
-All Relays
-Fusable link in trunk


That is all i can think off, TONS of new stuff... Hope i didnt forget

The problem: http://www.youtube.com/watch?v=rvM4Ly3tZ3M Notice Check engine light flash and rpm drop between gears

Car starts and drives fine, until harder acceleration and shifting. It'll run up through first with plenty of power, and i can shift to second. Problem then shows its head, the second i let off the gas and put in the clutch to shift, the check engine light comes on and the car looses all spark! (imagine turning your key off at 4 grand) RPM gauge will rapidly drive to zero. CLEARLY not reading true rpm anymore. A second later; light goes off, engine fires back up, and rpm reads. Then the same thing nest gear change..

Also Rare, but has been happening, Cruising down highway with cruise control, no gear change or anything.... Problem will show. Check engine light flicks on then back off, ignition quits, then car comes to life again as if nothing happened. But will backfire!!! I think due to fuel being pumped in with no spark, but then spark comes back.


What I do know. From what I read people think the car is loosing timing data and not wanting to fire spark for that reason. Common causes, bad DME, grounds, or crank POS.

I have eliminated all of these very well i believe. I also think I replaced all main ignition components...

What is the cause of this folks?!?!??! Its blowing my mind....

[FLG]

Oh man took me weeks to figure this out.

Disconnect the battery, remove the c101 connector (near fuse box) and clean it really well. Though i assume you did that already.

Next, did you replace the crank sensor with a NEW oem BMW sensor? If you did not, check what it ohms out at, should be 530 or so from what i remember. But if you did not use an OEM sensor id advise you get a new one regardless, i had tons of issues chasing down problems that turned out to be bad (not once but twice) new sensors that werent OEM from BMW.

Basically you now have to determine if this is a DME issue or wiring issue theres 2 pins on the DME that have power, one constant one switched from ignition. Easy thing to do is pick up some 12v led bulbs, and quick connects and tap into the 2 wires, if the DME is loosing power you will be able to clearly see that.

I chased down the same issue for weeks. It was absolutely horrible.

[ct3155]

I'll go to my receipts and see if the sensor was oem BMW... I buy so much stuff I cannot remember.

Also when checking with led bulbs: Just to be sure.. Should be pin 18 with ground and 37 and ground? Pretty sure that's right if I'm reading the Bentley correct...

[FLG]

Yep that's correct.

Did you thoroughly clean the c101 connector near the fuse box? Also pull back the rubber and make sure no wires are damaged.

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[ct3155]

Yep! All connections have been checked up on super well when I put the new engine harness in two months ago. So I'm pretty sure all the under the hood connections are good. Gonna try the leds now!

[ct3155]

Here is another quick update,

On start up, It will fire quickly but bring the check engine light on and spudder with spark cutting on and off... then light goes off, and runs normal.

Also it seems to be bump related... Like when you let off the gas quickly, or hit bumps on the highway.

So same problem but it exhibits it on start up / bumps now as well. meehhhhhhh!!!

[FLG]

Would Def just check the cps sensor. If you have a multi meter check what it ohms out at. Center pin and one of the outer ones will be nothing, other one should be like 520 plus or minus 20 ohms

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[ct3155]

Also just did the 12v LED to pin 18, 37, and ground. Drove the car around until it had its hiccup, NO FLASH!! No blink. no anything. Both LEDs remained perfectly solid. :(

Think it could have anything to do with the ignition switch / wires under dash??

[ct3155]

OHMS for sensor were 537 on the one i pulled from the car. The one that i installed this summer and rechecked today are 524!

So both of those seem good.

[FLG]

Is the new sensor plastic or metal? I remember the ones I've had with were facet replacements and they were a black plastic.

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[Danny915]

i was having a similar issue with my car[solution for me was AFM], some people told me to check the fused line in the trunk. Its located under the carpet to the right wheel well, a litte farther into the car past the battery.

[FLG]

i was having a similar issue with my car[solution for me was AFM], some people told me to check the fused line in the trunk. Its located under the carpet to the right wheel well, a litte farther into the car past the battery.

He's dropping timing data won't be the afm and checked the link already

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[Danny915]

He's dropping timing data won't be the afm and checked the link already

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I understand that was just saying that's what fixed my issue, it's impossible for it to be afm anyway, OP states he went with miller and maf setup,

[ct3155]

What's your guys opinion on bad ignition switch?? Would that cause the tach/engine to behave this way??

Or is it strictly just the loss of timing?

[ct3155]

Is the new sensor plastic or metal? I remember the ones I've had with were facet replacements and they were a black plastic.

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Also the new sensor I have is all black plastic. Just double checked. And it ohms out in spec.