First things first, my 84 sd25, would sometimes idle higher and then if you eased out on the clutch mometarily while holding the brakes you could get it to idle back to normal. The problem at first seemed would be more noticable in the wintertime, and now it got the point of all the time and was getting annoying. Along time ago, a wise gentleman on this forum pointed out to me to do the vaccum test on the diaphram and i discovered that it didn't pass.
Well, it's been along time since then and just got around to replacing the little rascal and it did clear up most of my problems so far. I still notice that when coming up to a stop sign or light after a period of highway speeds it doesn't come back to idle right away, but it doesn't idle up as high as it used to. I was hoping for a miracle cure when i changed out the diaphram, but I may still have a different problem. I problably need to see if my DPC is making the positions correctly but I'll have to set up my camcorder to do this. Thanks for all the help and suggestions.....
olpeppy wrote:_SNIP_ I still notice that when coming up to a stop sign or light after a period of highway speeds it doesn't come back to idle right away, but it doesn't idle up as high as it used to. -SNIP-
You've replaced diaphragm governor. Good.
Next. There is a metal line that runs between the throttle body to the diaphragm governor. Now... there are a couple of rubber hoses that fit at those ends and ... if you have a metal tee-line back rear the #4 cylinder then ... replace related rubber hoses. Your engine WILL have this metal tee going to a Coolant Temperature (onto your oil coolant) and a Vacuum Amplifier (just under the wiper motor) when your engine also has the Exhaust Gas Recirculation system (on the intake manifold).
Does your engine still have the little throttle "dash" on the bell crank?
The point here is ... ANY (and I mean -any-) little air leaks between the throttle body and the diaphragm governor will raise the engine's RPM.
olpeppy wrote: I problably need to see if my DPC is making the positions correctly but...
The DPC itself is not adjustable. But there is a plate on the Fuel Lever that can be adjusted so that the peg center's when the engine is ON (running).
-Philip Passed 08May2008
My friend, you are missed . . .
1982 Datsun 720KC SD-22
well, today i hope i put and end to my high idle problem. i was replaceing all the vacuum lines to the throttle body and through all the tugging and pulling i noticed that the entire intake moving up and down. i was very surprised to find that and went about tightenening all the nuts up. i know that the gasket problably needs replacing now, but that's another day. i so far have no problems with idle and it's alot quiter now. thanks be to all for the help and maybe it'll help someone else............
The whole intake manifold or the air throttle body? Either way, that would allow intake air LEAKS which would have the pneumatic governor increase fuel delivery (raise RPM).
Good for you!
-Philip Passed 08May2008
My friend, you are missed . . .
1982 Datsun 720KC SD-22
it was the entire intake manifold that was loose. i might add the bottom bolts were kind of tricky to get to. thanks for all the help and have a good one!!!!!!!!!!!!!
thanks be to all for the help and maybe it'll help someone else............