Jeep 4.0 w/6 tooth distributor wheel setup help

[Random Hero]

Heyas,

So I built an MS-II v.3.0 for my buddy's jeep stroker. In another thread Matt had mentioned that a lot of jeeps came with a single tooth wheel in the distributor, which was correct. So my buddy went and got a 6 tooth wheel out of a similar distributor, old wheel comes out and the 6 tooth bolts right in. It may be hard to tell from the pic but one of the teeth has a slightly slimmer profile.

I don't see why this couldn't work, but I'm gonna need some help getting the ignition settings correct so we can get this thing started up. Mainly the settings in red in the base ignition settings as well as the trigger wheel options. The only other car I've tuned with megasquirt so far ran EDIS, which was much more simple in retrospect.

Attached is a pic of the wheel, I think he said it came out of a ford.

Thanks,
Brett

[Matt Cramer]

Looks like a Ford TFI signature PIP distributor wheel, all right. Just be sure to trigger on the falling edge.

[bleoh]

Another option is the later 4.2 inline six from early YJ's and later CJ's. These will drop in to the 4.0 and are the same as a ford duraspark 1 distributor with a VR sensor and 6 teeth.

I have heard that the ford trigger window will bolt in place of the single window Jeep unit, but never seen it done. Do you remember what engine it came from? From what I have heard the late 80's early 90's v6 engines had the correct wheel.

Are you going to the six window to control a coil directly and send spark through the distributor (not using a crank wheel)? If that is the case the ignition settings would be similar to the Ford TFI but will also depend on if you are using MS to trigger the coil, using another module or CDI box, etc...

Brian.

[Random Hero]

Well. Just and update here, we actually got her fired up the first time we tried, which I consider and accomplishment being that this is the first MS I've built myself, and my buddy's first wiring job for anything this big.

When it does run though it is extremely rough, misses and backfires, have to keep the throttle open 10% to keep it running and pulls a terrible vacuum.

We are using the wheel pictured in the first post bolted into the Jeep distributor which apparently came from an earlier "Renix" 4.0 (all gibberish to me) to and running the coil directly through MS.I installed the high current driver as well as the hall/optical and VR inputs. Jumped to hall/optical right now.
The wheel is from an early 90's Taurus. I was triggering from the falling edge like Matt suggested.

I guess the trigger wheel settings just need to stay at 0 ? That's the only way we were able to get an rpm signal anyway. It's tough to diagnose any of the way these settings affect the way it's running because it pulls a better vacuum while it's cranking than while it's running.

It could very well be possible that the firing order isn't right (seems to fill all those symptoms) or the trigger offset needs to get matched with a timing light, I saw that on the Ford TFI settings the trigger offset could be up to 10*, but it seems like she still would have fired up and ran a bit better even if the timing was that far off.

[bleoh]

Congrats on getting her to fire up!

Renix was a pre OBD1 system used by in Jeeps in the late eighties. It was a combination of Renault and Bendix. In 1991 Jeep went to the Chrysler designed OBD1 compliant system.

Trigger wheel = 0 is correct. I "think" that lets MS know you are using a distributor with one trigger per power stroke instead of, say, a crank wheel with 36-1 teeth, etc...

The firing order is 1 5 3 6 2 4 and if that is not set up correctly it will run rough. Also, do check the timing with a timing light.

By the way, your trigger wheel looks like it has the same mounting pattern as the wheel I took off a 1993 OBD1 4.0 distributor. Good to know!

[Random Hero]

Thanks bleoh, I'm pretty sure something on his end is just not right. Distributor not clocked right, plugs in wrong order or cam timing off something like that. I'll keep the 0 trigger wheel setting (cuz thats the only thing that works lol ) but I'm pretty sure there is going to be a significant trigger offset being that his cam sprocket is adjustable and I think he has it advanced a couple degrees.

Once we can actually get it to run somewhat smoothly we'll see what we can read on a timing light.