Calling GM Tech's

blueoval98

Well-Known Member
Joined
Jul 7, 2005
Location
Lexington N.C.
I have a couple ?'s concerning my 84 Silverado 4X4.I just removed the 700R4 trans and went back with a th400.Was a used trans/tcase combo(th400/208).I installed it with a new convertor,modulator valve and vacume line,shift kit and fluid/filter..now for the ?'s...

1) When driving it shifts fine and FIRM.When coming to a stop it only downshifts to 2nd gear.At the stop can manually shift it to low and back to drive and it will take off in 1st gear other than that it tries taking off in 2nd...Suggestions???

2) I also noticed when the trans was out.The truck has the 4 wire plug that is supposed to hook to the dist. someone had used the plug from the dist side with wires cut and some taped together with it plugged into it.The current dist in the truck dosent have this plug.only the wires that connect to the cap..The truck will not fire and run without that plug someone made plugged into the harness..With this being setup like that could it be causing issues with the timing ,such as advancing it cousing it to hurt the power output of the truck????

Thanks in advance for your knowledge and time,
Paul
 
Well i went and hooked a vacume gauge at the modulator valve to check make sure it had vacume and how much..It showed 17-18 at idle..hooked it back up and took a ride..The downshift problem seems to be getting better as it downshifted to 1st most the time..still only to 2nd a few times though..:shaking: :confused: ..still curious about the wiring setup for the dist though..The truck runs fine and drives fine for normal driving..But if you get in the throttle or im sure if it had some weight behind it,just seems like a turd!! lol
 
The extra wires were for some oddball retard setup some of the mid 80's carbed GM's had. My old van had one and I ended up putting a earlier distribitor in it to cure a surge it had at highway speed. Apparently that was causing it. I forget what GM called it but its similar to Dodges afterburn system of the same era.


Sounds like the governor might be sticking.
 
The downshifting issue seems to be correcting itself..dosent do it all the time....Checked farther on the wiring issue on the dist.Seems it has the dist in it with the 4 wire plug with the other side of the plug plugged in with some of the wires taped together..The truck dosent have the plug for this type dist.
 
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