MS1 *ignition only* runs then dies.

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BigBlockRanger
MS/Extra Newbie
Posts: 15
Joined: Mon May 03, 2004 2:29 pm
Location: Amarillo, Tx.

MS1 *ignition only* runs then dies.

Post by BigBlockRanger »

Background. MS1extra, V2.2, Cherry hall sensor on MS-supplied 5v with pull-up resistor, 36-1 wheel, wasted spark using Pantera coils, and EFI Source igniter. Signal to stock tach provided using the diode circuit setup. The only input is the crank sensor, no tps, no map connected, no ect, no iat. I just wanted ignition control only right now.

This thing is interesting. I can crank it up, and it will run really good for about 3 minutes, varying rpm then holding it steady at 3000, then the tach bounces and it just shuts off like you turned the key off. Boom. Then it absolutely does not want to restart. I logged it and SecL does not reset until the rpm goes wonky. BattV is a bit odd in that it starts out real nice and gets progressively more noisy. MS 12v is currently pulled from the battery cutoff which is right next to the rear-mounted battery. I think am going to change that so it gets it directly from the battery post. MS and Igniter are grounded to the same spot on the block, but I just realized I do not have a block to body ground on the engine. It is just grounded through the motor plate, etc. Adding one may not fix it, but it certainly won't hurt. This will be the first thing I do.

I adjusted the hall sensor to narrow the gap in the event it was getting a weak signal. May change this from using an MS supplied 5v, to a 12v source.

I pulled the MS and gave the board a good once over. There were a couple of spots that needed attention. The two transistors for the Efi that are heat sinked to the case both had issues. One had one leg almost touching the center and the other 's legs were almost grounded to the case.

First dip in battv (blue) is when I turned the electric fan on. It is on a toggle and I typically run it all the time. Battv stays relatively stable, increasing with rpm, then it starts to get REALLY noisy. Starting to think maybe the 1-wire alternator's regulator is going bad or it is just mega-noisy by nature. SecL (green) continues to count up correctly and only resets right at the point the engine dies. Not sure if that is a cause or effect. Of note is the fact throttle position (white) continues to climb even though there is no TPS installed....
Log-Aug07.JPG
Life is short. Be a do'er and not a shoulda done'er.
1983 Mustang GT 552/C6
Matt Cramer
Super MS/Extra'er
Posts: 17499
Joined: Thu Apr 16, 2009 8:08 pm

Re: MS1 *ignition only* runs then dies.

Post by Matt Cramer »

Can you catch a tooth log of what happens when the RPM reading goes crazy? This will let me look at the sensor signal in more detail.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
BigBlockRanger
MS/Extra Newbie
Posts: 15
Joined: Mon May 03, 2004 2:29 pm
Location: Amarillo, Tx.

Re: MS1 *ignition only* runs then dies.

Post by BigBlockRanger »

I'll try to get that today sometime.

I didn't realize TS would do that until after it was too late to crank this thing up and disturb the neighborhood.
Life is short. Be a do'er and not a shoulda done'er.
1983 Mustang GT 552/C6
BigBlockRanger
MS/Extra Newbie
Posts: 15
Joined: Mon May 03, 2004 2:29 pm
Location: Amarillo, Tx.

Re: MS1 *ignition only* runs then dies.

Post by BigBlockRanger »

With the hall sensor moved in tighter and the stock tach disconnected, it fired up and ran like a top. Idle, sustained rpm, made no difference. Tooth log looked perfect on the screen, but appears to have some sync loss I think. Datalog show noisy 12v, but I ran it for about 10 minutes with no issues. Don't know if it was the sensor adjustment or the tach disconnect so I am going to reconnect the tach tomorrow and see if it was the root cause. It would not be a surprised if it was. These stock instrument clusters can be bizarre at times. Example: sometimes when I turn on my lights, the cluster is all wonky, random warning lights on, tach reading weird. Hit the top of the dash with my hand and everything works properly once again. Works every time. Haha
Life is short. Be a do'er and not a shoulda done'er.
1983 Mustang GT 552/C6
BigBlockRanger
MS/Extra Newbie
Posts: 15
Joined: Mon May 03, 2004 2:29 pm
Location: Amarillo, Tx.

Re: MS1 *ignition only* runs then dies.

Post by BigBlockRanger »

Also, how does the different 250ms, 500ms, 750ms, etc affect the log? I had it set to 4000ms, but do not really know why. Haha.
Life is short. Be a do'er and not a shoulda done'er.
1983 Mustang GT 552/C6
Matt Cramer
Super MS/Extra'er
Posts: 17499
Joined: Thu Apr 16, 2009 8:08 pm

Re: MS1 *ignition only* runs then dies.

Post by Matt Cramer »

Tooth log looks good. What's driving the tach, and where's the MS grounded?
Matt Cramer -1966 Dodge Dart slant six running on MS3X
BigBlockRanger
MS/Extra Newbie
Posts: 15
Joined: Mon May 03, 2004 2:29 pm
Location: Amarillo, Tx.

Re: MS1 *ignition only* runs then dies.

Post by BigBlockRanger »

Signal for the tach is provided using the "5 diode circuit" from the high side of the coils. I incorporated 4 of them into the igniter so I had a nice connection point.
20160723_160703.jpg
20160723_160912.jpg
MS is grounded to the engine block along with the Igniter.
Life is short. Be a do'er and not a shoulda done'er.
1983 Mustang GT 552/C6
BigBlockRanger
MS/Extra Newbie
Posts: 15
Joined: Mon May 03, 2004 2:29 pm
Location: Amarillo, Tx.

Re: MS1 *ignition only* runs then dies.

Post by BigBlockRanger »

Well, it seems it was fixed by moving the hall sensor closer to the wheel. Connected the tach, cranked it up and it ran and ran and ran. Datalog was clean with no resets. High rpm, low rpm, made no difference. I didn't have time to drive it, but I think I feex'd eeet.

https://www.youtube.com/watch?v=5P4bR0d_DIU
Life is short. Be a do'er and not a shoulda done'er.
1983 Mustang GT 552/C6
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