So, I've been trying to figure this out since I got my truck and I can't, so I need some help. Today I decided to take a look at what causes my truck to Idle rough so:
I checked the vacuum lines and they seem to be good , But i'm not sure where a couple go or what they even do.
I adjusted the distributor so it is firing at the right time
I checked all the Spark Plug/Coil Wires with an Inductive Timing Light, this is what i think is causing it to idle rough, I checked all the plug wires and they all seemed to work fine, but the first cylinder wire, If I watched the light on the Timing Gun, it would flash constantly, then it would stop for a split second, the Idle would go down then it would return to normal, doing this every 5 seconds or so, so I checked my Coil Wire and it flashed at a steady pace then it would also stop for a split second, the Engine would stutter, then it went back to normal. So I am wondering what to check, The distributor seemed to have clean contacts and the rotor was clean, but I could not check the wires leading from the Dist to the Coil to tell the coil when to fire. So i would like to know what to check to tell if the Coil needs replaced, the Dist needs replaced or if its just the plug wire that needs to be replaced

Thanks,
Andrew

Is it a 83-86, or 87 up? The setups are different for each type. Wires don't usually act like you are describing; it sounds more like a ecm adjusting for a bad input. Use an ohm meter to check the wires for continuity; bend them anywhere they look suspect to see if reading changes. They won't read 0 ohms; they will read some value depending on the type of wire they are made from.

It is an 87, yeah and it would make since that the ECM would do that because the person who owned it before me had done some "Custom" wiring, like the A/C no longer has vacuum control, it is now wired through a switch on the dash, which I think was done because it was low on R 12 (Its now an R-134a system) As far as I know there are two 8 pin connectors, one of them goes to the carb, and the other goes???? Also, when I try to look for the diagnostic code connector, there is not one just a couple of connectors that go no where but do not look like the connector shown in the Chilton book. So Im sure the ECM is not working like it should, if it still has one. I was just thinking of using a Weber carb, can you point me to the one that would fit???

Thanks
Andrew

This is an older video that I made on the 4th of July, the truck now has all the same size tires, the glow plug light is not a door ajar light anymore, and it has a radio, but i hope you can hear the engine in the video (I broke my PC's sound card, so I cant hear it) http://www.youtube.com/watch?v=7DW7djvBWjQ

my 86 had a 2.0 the distibutor cap pulled water in it all the time. which gave it rough idle or it would not start.

clean the cap out with WD-40 (then wipe dry) also ANY carbon build up in there will cause it to idle rough (old trick to get a car cheaper, carbon in the dist. cap with a piece of pencil lead)

Also i found "Quality" plug wires helped my truck greatly. I got build your own MSD (I think) wires back in the day.

good luck

mike

Also in the cap and rotor you can get a problem with ionizing air. You can put some small holes in the cap right where the rotor spins around. This will allow air to vent and cause more turbulence to stop the air from ionization

Funny, If I go and get a parts MM I will remember to bring my pencil. I drilled some holes and it does seem to help.