moparbay

First time poster. First I want to thank everyone on this forum as it has been the most useful resource during my project. I just got a 94 pickup with 3.0l with a rod knock. I have bought a long block and have it installed and running. I have ran into some issues and have fixed most of them with the resources in this forum.
Here is what I have going on now and have not had any luck running it down. I am not sure what the actual name is but I think it is a cold idle actuator or something. I have attached a picture of the part in question. Anyways, the only time the plunger contacts the adjustment screw is when the engine is not running. It appears vacuum causes the plunger to retract and loss of vacuum caused the plunger to extend.


Does anyone know how this is supposed to be adjusted and how the thing works?? Right now it is not doing anything as far as I can tell. The plunger pulses with changes in vacuum but never contacts the adjustment screw which would in turn open the TB valve to increase engine speed. I don't have a high cold idle, idle does not increase when A/C is turned on, and idle does not increase when turning the steering wheel at idle. I am not sure if these 3 systems are connected or not. the truck idles good now, right about 800 with all accessories off and only drops if I turn anything on like A/C, Lights, pretty anything that puts a load on the engine.


I have readjusted the TPS and throttle stop screws as shown in the
http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml article (which is awesome by the way) and that cleared up all of the low speed idle issue I was having except the idle up stuff. I also reset the timing after adjusting TPS. only issue I found after adjusting the TPS is there is no noticeable change in idle speed when jumping the pins in the diag connector, which the article said should happen. Who knows..


I do have to add that I am getting the 52 knock sensor code if I drive it but it never comes after resetting it when I am messing with the idle stuff, it only comes on after I drive it for a bit. I did replace the knock sensor pigtail but the engine harness that plugs into the pigtail the wires are frayed and I believe once I replace the pins in the engine harness connector, it will resolve the code 52 issue. Either way, the idle up issue does not change.


Please share if you have any info you may have. thanks

scope103

That's the "Throttle opener." http://personal.utulsa.edu/~nathan-b...93throttle.pdf It nudges the throttle open with NO vacuum (when the engine is stopping) to prevent dieseling. When the engine is running, it retracts out of the way. The link to the manual tells you how to adjust it. (And seriously: you've been reading posts here for a while and never noticed that just about 80% of the threads have SOME reference to the manual?)

The power steering and a/c idle-ups are not connected in any way. Both of those systems "short circuit" some metered air (that comes from the resonator below the air cleaner) into the plenum; more air is just the same as more throttle. The power steering pump has a pressure switch (passes air with high pressure inside the pump), the A/C idle up relies on a VSV actuated by the ECU when it closes the compressor clutch.

MANY older engines have a lot of "gunk" inside the plenum; on mine I had so much that it was covering the idle-up ports. Once I cleaned the plenum (a big job, by the way) they started working! You don't have to go that far; use the manual to track down which lines to the plenum are from the idle-ups. Pull a line off and see if the idle increases. Then pull the supply side line and see if you can feel vacuum with your thumb when you actuate A/C or turn the steering wheel to the stop.