Ok truck has been running fairly good lately but a few things that I am rolling around in my head to think of a correction that I cant even think of a starting point.


First off the truck has a roughness at idle and at 1,000 rpm when accelerating in traffic. The truck runs fine other wise. Also when cold the choke stays on and when its half open it will idle just under 1,000 in gear but will have a miss which goes away once choke is fully opened. Like wise if you force the choke open by stepping to the floor on it it will idle roughly.


Now this is the two things Iam thinking of.


First off I adjusted the timing from 8* to 11* initial after I swapped dist and ignition module and coil. I am wondering if I should reset the idle mixture and that is causing my problems.


Second I am thinking of is the 180* thermostat and if a 192 Motorcraft thermostat would correct the problems I don't see how as 12* difference shoudnt cause this kind of issue.


Third I only have the electric part of my hot air choke working which I cant see because the truck used to not miss when the choke was on and idling in gear.


Fourth, the air pump, I don't have conveters and my exhaust pops more now with 11* advance vs 8* and I am wondering if the air being pumped in the exhaust could be causing a problem. I know its leaning the exhaust out as my manifold temps are in the 600s.


I don't believe it is carb related as you can step down on it and the truck takes off. I also don't believe plugs or plug wires would cause this issue cause when it was running rough on me Saturday in stop and go traffic I held he brake and loaded the engine up fairly fast to 2,000 rpm and never missed so its not a load based miss.


I am at a loss on what to do to be quite honest. I can try adjusting the idle mixture on the carb and then pulling the belt off the airpump to see if that makes a difference. I could also swap in new plugs and new wires to see if maybe its some strange issue with them causing this.

 

I would first try the new plugs and hotter
thermostat. Cold engine temps On an early
smog engine can foul or gum up the plugs.
Why did you change the timing? Factory specs
are best for a stock engine. The best would
be to change the timing set for an aftermarket
non smog set. It can't be done right by just
moving the dizzy. Did you have this problem
before ya messed with it? Again with a smog
engine you need to run everything at factory
specs, Once the timing set is upgraded and the
engine is in good enough shape than you can
delete the smog pump and all the smog crap.
Than its ready for headers, maybe better heads
and like that. But only if the rest of the engine is
in great shape. Otherwise if it ran okay before
than undo all you have done and it should be fine
again. we need more info, And what is a C2??

 

I bumped the timing up to make more power the engine was such a slug at 8* and at 11* the engine runs great has a lot more get up and go. I did change the dist because of this issue which is when I put the timing at 11*. I didn't mess with timing initially when I had this driveability issue. But this driveability issue was a lot worse than this, droped dead on me two time so far since this driveability condition came about. I am trying to figure out which way to go case this is causing me to scratch my head and only thing I could try doing is purchasing 1982 factory shop manuals to see if that could help with this issue.


The air pump I don't think its doing anything as of now because I have no converters so the air is just being pumped into the exhaust.


Plugs are ash fouled I tried cleaning them with a wire brush but didn't replace them. The plugs are as old as the wires I think I did them back in 2009 or so.


That should be C6 I guess I hit the 2 by mistake on the numbpad

 

How many miles on it Rusty? Have you checked
to see how much play is in the timing set? I think
you know how to do this. But for the benefit of
others that may come here. Remove the plugs
to relive the compression (you are going to replace
them anyway). Than the dizzy cap leaving the rotor
cap on. Than rock the engine back and forth just
enough to move the rotor and see how much it takes
to move the rotor. it should be very little. This engine
was a smog dog from day one. It's only a 100K mile
engine before it starts needing some work. Not like
today's 300K engines. But you know this also. Again
how many miles? How are the vacuum lines and over
all vacuum on it? Does the C2 shift properly?

 

I could not say on miliage. Engine was rebuilt when we got the truck in 92 and be lucky if 3,000 miles a year was put on it.

I can check the timing set i know it has some slop in it if its too much i wished i replaced it when i did the timing gasket a couple years ago.

Trans shift just fine doesnt downshift while rolling without really stepping on it but might be the nature of the trans.

I can take and throw new plugs and wires on and the 192 motorcraft thermostat and retard the timing back to 8 degrees to see.

Might run fine at 8 deg with the proper accelerator pump. Last few i had at full idle there was a gap between the rod and the piston rod of the pump.

 

I don't see where you said what carb you have.
I assume a 2V Autolite or Motorcraft? Try tuning
it again before doing anything else and see if it
helps any at all. They should always be tuned
after changing the timing. But I am still leaning
twords a worn t chain if it wasn't replaced with the
overhaul in "92. So this problem developed after
the overhaul at about 3K miles? Be sure to retune
the carb after the new plugs and wires as well. Maybe
get what ya need to fix the Accel Pump while at Napa.

I re read your post and see that you said 3K miles
a year since the overhaul. That timing set has lots
of miles on it I think. Makes me wonder what else
may not have gotten a refresh in "92.

 

I cant see not replacing the chain at refresh time but????
I do think it is good to check the play in the chain just so you know.
Also adjust the carb with motor up to temp before doing much more and see what that does.


I would only deal with the up to temp running issue and not worry about the running ruff cold, for now. The only "cold settings" I can think of are for the choke & fast idle not much else for running cold from what I remember from back in the day.


I have had plugs that looked new, not much run time, only used to move car in & out of garage over a few years and would sit other wise. Well one day I needed to move the car and it had a bad miss at idle and back firing out the exh when reved up. Thinking stuck valve did a compression test and all was good. Replaced the new looking plugs and all was good so the "look" of plugs is no way of telling how they will work.


On a side note my 02 Durango has a miss at idle, not under load. Compressing checked out good. New plugs, wires, cap & rotor, cam & crank sensors and PCM all replaced before this miss started because of a no start/ tow in to dealer.
The dealer was able to track the miss to 1 cly and on leak down found it down 30% because of the exh valve they said. They are doing a valve job to it only has 175K on it. Oh the VJ better fix my truck or I am not paying for it!


So just shows what a leak down test might find.
Dave ----

 

1st off, you choke is not electric, it's electric assist. It's not going to kick down on time and quit idling so high until you put the hot air back on it.

I have been a couple rounds with these engines, and I can tell you what I found out; Once you start undoing things and changing things around, you really can't get it to run perfectly.

The major thing I found at idle was with the original carb, it always wanted to run a little rich. And if I tried to adjust it out it would not run correctly. What I have figured is some of the emissions stuff I had taken off actually were controlled vacuum leaks that added air to the carb, which would supply the engine with more air but leave the butterflies in the carb in a more closed position. This affect tip-in and when the other circuits in the carb were activated.

If I adjust it like it was supposed to be, then the exhaust was very smelly and rich. On one of those trucks with the original 2bbl carb, I actually added a vacuum line to the aircleaner and let it suck air all the time. This actually worked well, cleared up the exhaust, the idle adjustment came back in, and everything worked great. A little weird but it worked. The other solution I have found to fix the whole thing was to put a aftermarket 4bbl on it. That cures everything and gives you a little more power also.

 

Carb is a autolite 2150 if I remember right.


I got to thinking wondering if maybe this rough idle is not a lean condition but a rich condition. I pulled a vacuum line and induced vaccum leak, seemed to run smoother but was hard to tell as the truck in gear started to run smoother at idle in gear when I got home.


I know the air inlet on the choke housing is plugged off since the choke tube broke. I will be ordering some plugs, plug wires, reset the carb, drill out the manifold and hook up the hot air portion of the choke. Then I will go from there.


Just need to find out where to get the tube from the choke to the manifold. I found a oem fresh air tube from the plug to the bottom of the carb horn and the plug itself but need to know the size to drill the manifold properly.

 

If it is running rich, it may take a couple of runs for the soot to burn off the plugs.

 

Thats the thing when i pulled the plugs to clean them they were sooty. Two had a little ash deposits but i cleaned them up.

I am thinking the plugs or the wire could be bad internally causing the miss and cut out which is like a hard heavy miss for one cylinder

 

Well in induced a vacuum leak running a hose from the choke to the carb horn. Up side truck never idled that smooth in gear in cold weather. Down side is driving down the road the cold air in aircleaner closed the choke.


So I reset the carb and plugged the choke off again till I can fix the choke properly. Runs better now but reving engine in park results in a the engine almost stalling as the rpm drops off. will try it in the morning then move the screws out 1/2 turn to see if better or not.