kataklysm01

Hi folks,

the EBL has been great with the 401 all winter. So I've been converting to let the computer control the spark. I've got everything wired up and it's not firing. I'm going over everything I've done and checking voltages.

My first question is; I have an MSD distributor and MSD Offroad (same as MSD 6) box. I'd like to keep it if possible. I just can't find any diagram to show me how to wire it for my situation.

Basically this is my setup.

-TFI coil
-MSD 6
-GM 8 pin module and plugs
-EBL

So I wen't with the diagrams, MSD install sheets and the install from Bigscaryjeep. I'm having a hard time locating the tach filter for one thing. So what I did was the Mag Pickup goes to the Control module like diagram shows, the Module via the two wire weatherpak plug goes to the MSD box via the green and purple wires. The 12V Ignition goes to the MSD box, I don't have a 12V going to the + of the TFI coil though, cause I thought that would come from the MSD box. I checked the voltage of the orange wire on the MSD going to the coil + and I get 5V coming out of the MSD box, I can't figure out why. All diagrams have 12 V from an ignition source.

The module is on a flat metal bar, with heat sink compound, and I ran a dedicated ground wire straight to the battery to be sure.

Anyway, as you can see I'm no wiring genious. Any help is well appreciated.

For testing porpuses. I'm thinking of bypassing the MSD box for now just to be sure that the whole setup works. It's just the distributor instructions say it has to be used with an MSD box only, if that's true or not.

RBob

iTrader: (1)

Can you post a link to the instructions?

Basically, the mag pickup wires go to the P & N terminals on the ICM. The 4-wire connector on the ICM goes to the ECM.

The 2-wire connector on the ICM, the one marked + (pink wire) gets IGN+ voltage. The one marked C (white wire) normally goes to the coil minus. In this case it goes to the points input of the MSD box.

You are correct on the coil, all it gets are the two wires from the MSD box. As it hits it with 400 volts to charge & fire it.

Once you get it working make sure that the timing advances once running under ECM control. If it retards then swap the pickup coil wires going to the P & N terminals of the ICM.

RBob.

Ronny

iTrader: (1)

What is the model # of the MSD distributor?

kataklysm01

Thanks guys,

I'm using these links that I printed off, plus one picture I can't find the source anymore;

http://www.ifsja.org/forums/vb/showt...=timing+howell

ftp://ftp.diy-efi.org/pub/gmecm/manu...47/747ecm6.jpg

http://www.msdignition.com/WorkArea/...id=15032386151

This is the distributor; http://www.msdignition.com/Products/...stributor.aspx

It's starting to make more sense, I'm a visual type. Slow but I get there eventually. I'll re-read Bob's post about 50 times and ask more in a bit.

kataklysm01

k, I think I see my error now. I need to ignore the mag wires of the MSD altogether and use the white wire on it, for points. Makes sense. Thanks guys, you made my day.

RBob

iTrader: (1)

OK, got it now.

> MSD box via the green and purple wires.

They don't get used on the MSD box.

The pickup coil wires in the distributor go to the P & N terminals on the ICM. The link with the install pictures, that is the red connector on the ICM (see post # 5).

The white wire of the MSD box is used for triggering the MSD box, that goes to the C terminal of the 2-wire connector of the ICM.

The + terminal of the ICM's 2-wire connector get +12 volts ignition switched.

RBob.

{edit: yep, you posted as I typed}

kataklysm01

k, second question. The Tach output of the MSD splits in two. One probably goes to the tach, the other goes to the Howell harness. I know we have the tach filter in there somewhere. Is it worth for me to even find it? Or should I just cut the wire going to the harness? Is this still being used with the ICM in place?

Ronny

iTrader: (1)

Clue me in please. That distributor is for a NON EFI vehicle. Is there a work around? I read once MSD does not offer a EFI distributor.

kataklysm01

I'm not following. What would an EFI distrib look like? And what better candidate than these. It's built to be able to remove the mech advance and lock it out and to disable the vacuum canister. Which I did. No need to weld this or that. I only wish it had a wide cap like the Ford.

Ronny

iTrader: (1)

It needs to receive input from ECU.

are you not using ECU to control SA? Your thread title says you are?

computer controlled:

http://www.performancedistributors.c...mputerdist.htm

RBob

iTrader: (1)

Ronny, he is interfacing the distributor to a GM 8-pin module. All is good in that area, at least once it is all wired.

RBob.

kataklysm01

I have spark now, so things are looking up. I just need to set the proper initial SA in the computer. Now, about that tach wire going to the Howell harness, what say ye? Keep or lose?

RBob

iTrader: (1)

Most likely needs to go away, and the 4-wire connector on the ICM gets wired to the ECM. Need to have those four wires going to the ECM for it to control the spark advance. Once this is done can also enable code 42.

The Howell tach filter just shapes the coil - voltage to be compatible with the ref+ input of the ECM.

RBob.

kataklysm01

I was too optimistic. I don't have spark it seems. In taking voltage readings, I discovered that the white wire on the msd is pushing out almost 12v at key on. Which makes no sense if it's to be connected to the C pin of the module. All diagrams show the C pin as a negative connected to the negative of the coil. Something doesn't add up. Is there supposed to be 12 v at both leads of the 2-wire connector?

kataklysm01

I think I'll bypass the MSD box next and follow the simple version.

RBob

iTrader: (1)

That is correct. The ICM will pull that voltage down (almost to ground) when it is time to charge/dwell the coil. Then un-ground (release) when it is time to fire the coil.

You can use that fact for testing, ground the white wire of the MSD then release it (un-ground), at that time the MSD box should fire the coil.

Just be careful, there is a lot of voltage on both the primary and secondary sides of the coil...

RBob.

kataklysm01

Well, I've made some headway tonight. Tested the firing of the MSD, tested continuity of all my wires from plugs to ECM. All was well. I even cranked and spark IS coming out of the plug wire going to the distributor cap. That's as far as the electrons flow though.

I'm thinking I did something wrong when I got rid of the advance mechanism, as per the MSD instructions. I had marked the position of the distrib and rotor and everything lined back up when I put it back in. I thought I screwed up the mag, but if I get spark to the coil then the ICU is getting feedback from it. So I'm thinking it has to do with cap/rotor. Maybe I screwed up the height, a shim... that the rotor and the electrodes don't line up?

kataklysm01

This is what I did, from a post on MSD tech forum;

First you'll need to remove the weights and springs. Remove the roll pin from the drive gear, then remove the gear and two bushings. The shaft can then be pulled up through the housing. Under the weight plate assembly, there is a nut that holds the advance stop bushing in place. Remove both the nut, washer and the bushing. The assembly can then be pulled up and separated from the shaft. Turn the weight plate assembly 180 degrees until the stud lines up with the small hole opposite the slot where the advance stop bushing sat. With the stud all the way down in the hole, reinstall the nut and washer. Reassemble the distributor and you're done! Remember that the springs and weights are not reinstalled.

RBob

iTrader: (1)

Make sure that the spark has someplace to go, don't leave it up to it to find a path to ground. This way it doesn't arc inside the coil or down the shaft of the distributor.

The instructions to lock out the advance in the distributor is correct.

RBob.

kataklysm01

Well, progress again today. Tested the distributor, sparks and all. All is good, I made a mistake about the fuel. I ASSUMED that the injectors were firing. This EFI stuff is still new to me I guess. So correction, I have plenty of spark. The injectors are not going.

So, I suppose the ECM is not getting the required signal to fire the injectors. My first guess, that wire with the filter that I cut going to the ECM from the tach signal of the MSD box. I guess tomorrow is finding which pin it goes to and run a new wire to it with another pin. That way I'll leave the old one in place in case I need to revert back.

Any other thoughts? I thought there was a signal line between the ICU and ECM via the ABCD plug. Maybe I was wrong.

kataklysm01

The injectors fire and the jeep starts when I reconnect the white wire. But won't idle for more than a few seconds and the tach kinda freezes up. I can't find where that darn white wire comes out. There's only one in the harness and it comes out on pin A9 which is apparently an ALDL pin B. So I put 12v to the end of it, at the plug I then get 2v (two volts) from A11 which should be a sensor ground. I guess I'm gonna have to fish the darn wire through everything.. yay for me.

kataklysm01

Finally got it running, friend came over and pulled the whole white wire out. And there it was the little circuit board filter. Damned thing is powered and everything. Just a matter of fixing the wiring mess, getting a better cooling solution for the ICU made of aluminium. Must have some type of heatsink somewhere.

kataklysm01

Ha, finally put a piece of junk computer hardware to work. Took the heatsink from the old Nvidia 8800 GT, it's got a copper block going to heatpipes and aluminium fins. Should keep the ICU at SubZero temps for sure. lol The ICI is ziptied to the board for now... I'll make a better clamp someday... yea right. I'll take a picture tomorrow, good for a laugh.

kataklysm01

As for which pin has the filter on it. I forgot to take note. I will tomorrow. The white wire goes to the filter, it changes color to orange at the ECM plug.

kataklysm01

alright, didn't have time to screw with this all week. So, I'm able to set the timing with the Bypass disconnected as I should. It runs great with it disconnected. So if I reconnect the Bypass it sputters and dies if I connect the tach wire that Howell used to have, minus the filter. If I disconnect that tach signal to ECM wire, I'm able to idle extremely rough and I can't touch the throttle or it sputters and dies. WTH? I tried with my base timing at 15, and now it's at 0 on the Distrib and at the SA initial value(yes values matching always).

I enabled Malf flag 25 - 42 Bit 0 EST 42. I've disabled the bit 1 IdlSA to try, no diff.

What am I missing, besides a few braincells?

RBob

iTrader: (1)

Did you verify that the timing advances with the EST/BYPASS connected?

RBob.

kataklysm01

yes we did. With it disconnected if I give it gas the timing is retarding from 10 to 0. My RPM is jumping from idle to 7000, the injectors DC% is jumping around and I see flashes in the 200%. I'm wondering if it's my soldering job on the EBL that is causing this?

I might have to return to the way it was for now since I kinda need my vehicle.

kataklysm01

and with it connected the timing didn't seem to advance, and all the erratic behaviors came with it.

RBob

iTrader: (1)

This is with a timing light? If so then something is wrong. As the module has built in advance for limp mode timing.

As for the other stuff going on as seen in the WUD, I suspect that the ICM isn't wired correctly to the ECM. Also be sure to ground the base of the ICM.

The 4-wire connector on the ICM needs to be wired directly to the ECM, all 4 wires. No filters or such in between.

If there is a tach in the vehicle, disconnect it from the ICM/coil until it is all working correctly. Then wire it to the coil.

RBob.

kataklysm01

k thanks for all the help, I'm back to mechanical for now. Need a break from it and miss driving the jeep.