78' Scout II 4 cyl. issues?

No this texan just hasnt figured out how to post them so I have been emailing them to mayben. Any other issues out of you and I May have to shoot you! Lol
 
michael mayben said:
I dunno!!!

This is a new item to me and I'm still doing some research!

But what I suspect is... At some road speed vs. Engine temp, the box does something which creates an additional vacuum "leak" in the fuel/intake system. That in turn does something with the intake charge for a period of time until; the system turns "off" again.

In your case, the system May actually be failed right now so it's turned "on". Let me do some additional research on this.

It's always something new around here, when IH "changed" stuff, there was really no mention of this except as part of a service letter that went out to dealers. We do have some of that stuff, but the majority is simply laying out there somewhere. A few of us know where the majority of it actually is but getting the folks that have the stuff to turn loose of it in some manner has not been successful.
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That box is part of the dtm - decel throttle modulator. Give me a ring if you need some info about how it works.
 
wiggins said:
no this texan just hasnt figured out how to post them so I have been emailing them to mayben. Any other issues out of you and I May have to shoot you! Lol
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Yea I knew it was mm who failed to post the pix. Just poking fun at ya'll.. :d

most played music in my garage is old school c&w.
 
I think it was alittle later than easter. My wife has been taking pics of the girls in our blue bonnets every year since they were born. This was 2 years ago, they are so much bigger and badder(is that a word) now! We now have a 4yo girls, a 2yo girl, and a 6mo yo boy! Yes its like a zoo!
 
ihojeff said:
that box is part of the dtm - decel throttle modulator.
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Just to further some info on this part... My 1977 ss Scout II had one of these, and the fail mode on mine was a slow vacuum leak with the dashpot on my 2210 slowly coming on over time. Made for difficult tuning, now that system has been optimized.
 
Any "decel" system is nothing more than a controlled vacuum leak that begins and ends within a certain parameter.

I'm suspecting that this dtm even is not turning off when it should.

I finally found some information in the service manual regarding this device, however, it's not used on every vehicle across the board. Here's the poop:
 

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May explain the erratic behavior. When it diesels out the rpm's are staying up making them a little to high to kill the engine cleanly and when it backfires the rpms are low and thus the fuel is not burned off leading to the backfire? Does this make since, just thinking out loud?
 
wiggins said:
May explain the erratic behavior. When it diesels out the rpm's are staying up making them a little to high to kill the engine cleanly and when it backfires the rpms are low and thus the fuel is not burned off leading to the backfire? Does this make since, just thinking out loud?
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Kinda.

The curb idle speed is way too high when the dtm fails. That means it's going to "run on" after turning off the switch. Most any engine will do that to an extent if the curb idle speed is too great.

Simply eliminate the switch by bypassing and tell us what happens.
 
Will do, it May be a few days, I am not off work for a while now. Weathers bad anyway. But I will let yall know the results. Here is a pic of my unrestored Scout we have been talking about. Just wanted to show it off a bit.
 

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Thanks Jeff! (and everyone)

some knucklehead had just found a vacuum hose lying around and decided that the top of the dsm was the place for it... Nope!!! Leave that alone..

Everything works as it should now!
 
Ok everything has thawed out and I have some results. I finally got to take the Scout out for a decent run since unplugging the top of the dsm vaccum pot. It ran good and killed good. For research purposes I decided to see what it would do when I disconnected the dsm system all together. So I unpluged the vaccum lines and unplugged the wire harness that goes to the ditributor. Took it for a run and it dieseled out a small amout the first run but killed fine on two more runs. Next I will re power time the Scout with the dsm unconnected and see if that makes it perfect. I suspect it will. Probably wont be able to do this until later in the week.
 
Sorry for the delay guys, but the weather is bad agian and will be for a few days and I just dont drive my cars in this type of weather. I will get back to yall though.
 
Ok I finally got to play with the Scout again. Earlier I had disconected the dcm system but hadnt had a chance to retune the thing after doing so. I now have power timed it and drove the Scout all day long. It ran perfect. Pulled it into the barn last night and it seemed like the idle was a bit higher than it had been all day long and sure enough when it killed it the Scout spit a sputtered a liitle. I cranked it right back up, the idle sounded normal and it died normal. So I thought it was fixed but now I am not so sure.
Forgot to mention after I power timed I went to back the Scout out ot take it for a run and the clutch felt stiff. I decided I had better get out and see what was going on and to my disbelief my transmision crossmember had come unbolted and was hanging about 6'' below the frame. So after fixing that I took her for a drive. Gotta love these old scouts! Crazy thing is the 2 nuts were still sitting on top of the bracket that the cross member was bolted to, must have just happened.

Also I would still like to keep this Scout original so if anyone has one of these speed sensors(dsm's) I would be interested, thanks wiggins
 
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