1989 BMW 325i with Turbo M20
MS-II Extra January 5th, 08 revision
MS-II v3.0 PCB
Single VB921 with stock coil and distributor ignition system
2.5ms Dwell
85lb-hr Low-Z Injectors
Scosche Injector FET Mod

I'll take it for a drive and try and get a datalog and msq.

Primary Ignition Current Ramp (50mV/division,2ms/division,1A/10mV using R43 voltage drop)
http://img297.imageshack.us/img297/9418/img8895jn5.th.jpg
http://img297.imageshack.us/img297/5968/img8896ew0.th.jpg

Primary Ignition Voltage Waveform (0.5V/division,2ms/division)
http://img99.imageshack.us/img99/4277/img8902xn2.th.jpg
http://img99.imageshack.us/img99/2710/img8903nf9.th.jpg

I tried to capture the sound of the misfires on video, but all you can really here is the valves.  Here's a link anyway.

http://www.youtube.com/watch?v=EalN3lqpleg

Hi Bob, I cant see that very well.

When I double clicked on it it was bigger, but still.
I hope some one else has a comment.

el101bob wrote on Jul 17^th, 2008 at 11:29am:

1989 BMW 325i with Turbo M20 MS-II Extra January 5th, 08 revision MS-II v3.0 PCB Single VB921 with stock coil and distributor ignition system 2.5ms Dwell 85lb-hr Low-Z Injectors Scosche Injector FET Mod I'll take it for a drive and try and get a datalog and msq.

I would say for the kind of vehicle you've got set up there and the kind of diagnosis you are looking to do that you may need to make use of a DSO (digital storage oscilloscope).

I would recommend making and sharing the following captures:
    - Primary ignition coil current, primary ignition coil drive, and enough time to show all the cylinders during the misfire (with a cylinder trigger)
    - Secondary ignition pattern with all cylinders during the misfire
    - Injector current waveform (preferably at a common point like a fuse or harness), injector drive, and enough time to show all the injectors during the misfire (with a cylinder trigger)

I would also like to know what the firing order is.  If you have access to a gas analyzer, I would recommend recording the readings during the misfire and sharing those as well.

Hey Bob,
Noticed the plug wires you have on the car..motronic has an uncanny ability to learn the(internal) correct fuel map to get you on. The way I have found best is to let it idle for 5 minutes--complete a warm up cycle, turn the a-c on and idle for 5 minutes(load sensor) then drive normal till you get in 3 rd gear , then do a full tilt hard pull on the engine. May want to drain the learned values before you attemp this procedure. I have setup a scirroco CIS turbo`ed car once using the Motronic controller--would blow off a vr-6 with the 100hp supercharger...talk about torque steer :-) What are you using for fuel enrichment and boost control? I noticed a few hoses coming from your intake plenum? I used a couple of fuel injectors (cis style) fabricated into the plenum controlled by the merkur turbo boost control devices available back in the day. Once I got all that setup the motronic controller took over and did a sweet job of getting me on the right curve. Your valve`s do sound noisy-Is that the spec for the cam?..perhaps a relash--critical on that engine. Perhaps you should try the OEM wire set-grounded.Ought to be some sleeper when you get it tuned :-)
You have alot of device`s there i`M NOT familiar with..hard for an ole dog to hunt with new technolgy sometimes. SLow down with the camera and give us some more pics of your basic set-up with an explanation of controls. You using a MAF or Airflow sensor or what? May find some info to help you at  http://www.splitsec.com/

Nowdays they make kit`s....

Nice laptop software?? Got any  uef or dbc datbase files to share?
Looking for any vector/canoe databases files I may be able to use in my playing?
Dave

Hi Bob,

Your secondary voltage trace shows the coil charging for ~2.4ms and then firing...

the spark line is ~1.2ms...

your primary current shows the coil being charged;

I'm still new to diagnosis-by-oscilloscope... those waveforms look ok to me...

Dave indicates you need to capture some waveforms with motor under load... a bit hard to do driving around with a "real" oscilloscope.

Cheers
Joe