Weird Chrysler 2.2/2.5 realization.

[Fastspec2]

A bit of a story. Bare with me.
3 years ago i bought a turbo Chrysler minivan with the factory 2.5 liter turbo. I intercooled it, built some cool parts for it, hung a gt3076 on it and I was originally going to use ms2 but reading the forums revealed some problems with the 2.2/2.5 chrysler ignition mode, so if i couldn't get sequential using the factory dual hep, i decided to save some cash and I installed a megasquirt I on it. I tried to get it running and was never able to get the rpm pickup to work properly. I was trying for a simple trigger running the one hep sensor in the distributor that the factory manual denoted as the crank sensor. I just left the cam sensor disconnected. After a lot of fussing with it i determined the issue was with the crank input, so i took a spare MS2 card, installed it, turned on the crank filters and blamo! I had hot water. I did some math to determine the min time at 6500 rpm to set the filters and with those values, the van ran great. With water meth and 28psi or so it made 268 HP through the auto and was good for high, high 12 second quarter mile runs. I drove the wheels off the thing with no issues. 20K miles and never a hicup. I sold it to a friend a year or so ago who still daily drives it with no issues. The only change made since then was wiring and tuning the stepper idle control.

Fast forward to last weekend, I decided to MS my girlfriends old autocross car, a Dodge omni glhs. I wired it the same as the van, and went to fire it up on the van tune file and it started but ran very poorly, like the timing was waaaay off. I checked my harness and realized i had mistakenly hooked up the harness to the white connector on the dist. the service manual calls this the cam sensor. I plugged in the other sensor and the car started and ran fine in the garage. Some quick ve table work and set static timing and i had it idling and driving around the yard pretty darn well. I got busy doing some yard work and didn't think much of it. Then it dawned on me mid lawn mowing that it should not have ran at all on the cam sensor if it only gets a cam signal. I went back and pulled the dist cap and looked at the vanes in the dist. it has the standard 4 vane dist with the window in the one vane. I looked at the dual HEP sensor and realized the both sensors are are on the same plane. I had always assumed one hep was at a different height in the dist and one read the vanes, the other read, vanes and window. I was wrong, they both read the windows and vanes.

So this suddenly gave me the AHA!! moment of why the van didn't run on the MS1. Because with the single hep seeing both the window and the vanes, the rpm pickup was all over the place. 3 vanes evenly spaced gave an accurate signal for them, then the window counted another pickup event 10* of dist rotation later. That of course caused the ecu to think the rpm just went from 300 while cranking to around 2200 then back to 300. Switching to MS2 and turning on the filters instantly fixed it. I'm sure because the filter values i used "tuned out" the window in the vane even though that was not my intent or understanding of how the system worked.

So a few questions.
1) does it sound like my above theory is correct in regards to why both cars seem to run fine on ms2 with the filters on?
2) What is your opinions of running both cars in this way? On one hand i realize now how its wrong now, but its hard to argue with how well both cars run with this arrangement and how i have had no reliability issues with the van running a fairly aggressive boost/timing combination (especially considering the super humble stock parts in the engine). This leads me to believe that my timing is consistent and reasonably accurate.
3) Do you think there is any real world improvement in changing them to a more correct method? 36-1, or at the minimum, get rid of the window in the one vane.
4) Has there been any progress on fixing the 2.2 2.5 Chrysler ignition modes?
Thanx for any and all input.

[Matt Cramer]

The Chrysler 2.2 / 2.5 ignition mode has been redone to use just one HEP as it seems the problem was with the angle between the two pickups sometimes being out of tolerance. I'd give the new Chrysler 2.2 mode a try first.

[Fastspec2]

PFFFFF! Tolerance issues with a 1980's Chrysler knock off of a 1970's German economy car? I don't think you know what your talking about.

I'll give the new 2.2 a try. Thanx

[Fastspec2]

Got a few minutes today. tried running the 2.5 chrysler igtnition mode. Worked fine for in the garage. the input capture had to be rising edge to work. Strobed and set timeing. stays solid with rpm so i think thats it. Will get it on the dyno this week hopefully. Also need to drill the dist cap to check phasing.

Thanx Matt