Author Topic: Severe Misfire (Read 3625 times)

kurtf114 · « **on:** August 15, 2010, 02:04:44 PM »

A couple of weeks ago while driving, my 318 started to run terrible. It had no power, smelled terrible, and sounded like a Subaru STi.
After looking at it, Cylinder #2 and #4 are completely not firing. We checked the wires, and plugs and they're working fine, except every cylinder gets spark expect for cylinder #4. My coil pack was looking pretty haggard so I went out and bought a new one. Still no difference, and cylinder #4 was still not getting spark.
I checked the injectors also and they're also working.

Any ideas of what this problem is/ what I could check?
Its a 95, and the motor only has about 80k.

Thanks for any help

KenC · « **Reply #1 on:** August 15, 2010, 04:17:31 PM »

Swap in a good DME and recheck.

DesktopDave · « **Reply #2 on:** August 16, 2010, 09:13:45 AM »

Don't mean to be a jerk about this, but you do have the coils & wires correct, right? Coil harness 1 goes to coil 1 which goes to cylinder 1, right? Wired 1-2-3-4 from rad to firewall?

Ken is right about the DME too. The early e36 had a problem with plugged water drains in the passenger-side plenum. Pull the little elephant trunk & see if it's clogged. If you had a recent storm or power wash the plenum floods the DME and makes it unhappy... Pull the DME and check it - the case shouldn't have any evidence of water at all.

Run a stomp test too. They're cheap & might be helpful. Check the cam & crank position sensors next...cam must be about 1200 ohms, crank 600 or so.

Then test the other components one by one. Coils are hard to test, but you've swapped them already.

kurtf114 · « **Reply #3 on:** August 16, 2010, 09:59:18 PM »

Yeah, the firing order is all correct.

I actually pulled the DME today and there was no sign of water.
I will check the camshaft and crankshaft sensor tomorrow.

thanks

xsjado · « **Reply #4 on:** August 20, 2010, 02:36:59 PM »

same thing happened today to me while driving my e30(e36m42)...suddenly just sounded like 3cyls firing...goona check it out tomorow,hopefully it nothing expensive

DesktopDave · « **Reply #5 on:** August 20, 2010, 10:04:08 PM »

Each of those coils is grounded by a big transistor in the DME. It's unlikely, but possible that one or more transistor has overheated and failed due to wiring shorts or a bad coil. In that case the transistors and coils both die a mutual death...adding a new coil will not fix the problem, and may even damage the new part.

Did you get any results from a stomp test? It's easy & free. That might help pinpoint what the DME thinks is happening.

xsjado · « **Reply #6 on:** August 21, 2010, 02:10:30 AM »

i have spark i have fuel...now for compression test....OMG ..expensive...should port the head if everything needs to come out....