Problems with MSD HEI coils and settings

[matt325is]

Hey guys. I got 3 MSD HEI 2 post coils running on my 89 bmw 2.8l 6cyl turbo. Stock VR sensor and 60-2 trigger wheel work very nicely with 029q2 code and such for the most part, currently getting rpm drops and ECU reset (random and during high load at 4500-5000rpm), which could be the shielded VR wire too close to the new coil location). I have run into a few problems howerver.

I had MS running an MSD 6BTM box that controlled a Blaster SS coil that went to the stock distributer. I got rid of this for 2 more VB921s and the three MSD coils to run waste fire. I got it all hooked up and ran great fora day. However, at high rpm I get tach signal drops. This also happens randomly while driving around (very similar to Petercip's problems in this thread http://www.msefi.com/viewtopic.php?t=18496). I'll post all of my timing settings below.

Also, today while driving to work I was accelerating normally on a 50mph road from a stop. Just after I stopped acceling, my car died. RPM signal comes in, LEDs signalling ignition events are all firing, but I coasted it into a parking lot. I tried to start it but it would run on a few cyls and die, even at full throttle. So I towed it home with a strap. When I got home, I cleaned the spark plugs, replaced the VB921s (thought they might have burned up or something), and it is still missing on a few cylinders. Could one of my coils have burned up if my dwell, and other settings were not perfect at higher rpm? The RPM drop/reset usually occured at around 4500rpm when under load, but never happened when no load revving, its really weird (maybe the VR sensor wire is too close to the coils?).

Here are my settings, tell me if they sound right to you.

Dwell Control:
Cranking Dwell 3.0ms
Running Dwell 2.3ms
Min Discharge .2ms

Specs on the coils:
Maximum Voltage: 40,000 V
Turns Ratio: 80:1
Primary Resistance: 0.350 ohms
Secondary Resistance: 7.8K ohms
Inductance: 4.2 mH

MSD spark plug wires. NGK spark plugs at .025.

For dwell settings I calculated T=(-L/R) x ln(1-(RxI/E). T=(-.0042/.350)xln(1-(.350x6/12)= .002308 seconds = 2.3ms. Does this sound correct for these coils?

I'm going to strobe the spark plug wires tomorrow to see if all of the coils are firing. Could a coil have burned up? Any other ideas possible?

I know this is a lot of info, but if you could help, I'd be quite greatful. I'm stumped...



Thanks,

matt

[matt325is]

Well, I seemed to have solved the problem I think. I rerouted the VR sensor wire to the drivers side of the engine, away from the coils. No more RPM drop/ECU reset. However, I am scared to take it to higher rpm (4000+) in fear of burning up another VB921. In the earlier post, when I replaced the VB921s and still had a misfire, it was due to a bad spark plug, I replaced it with a new one, and it fired right up on all cylinders.

Another thing to note, when this all happened yesterday, I tried cranking it over when it first died, and the starter had a LOT of load on it, and didnt want to turn the engine. This really had me scared (thoughts of blown engine went through my mind for a while). It was actually a hydrolock due to too much fuel I'd assume. I checked my oil and it smelled like fuel/oil, and felt like solvent. I changed my oil of course, and it runs fine now. Any ideas on to why this hydrolock may have occured?

Any ideas on the proper dwell settings for the 3 MSD HEI coils on a BMW 6cyl, running 3 VB921s? Thanks guys.

matt

[Jon k]

Any updates Matt? Working better?