88 D100 issues

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Ok. Buddy came over. Popped the distributer cap off to have a look. Didnt look that great but not horrible. Went to put it back on and we noticed the distributer moved. It was loose. Got a new cap and rotor. Put it on. Started it set timing by ear. Set timing the proper per manual. Truck is doing better but idle to high. Now we notice the idle speed controler is not backing off at all. Even when shut off.
 
Usually something simple. I get tunnel vision and have to walk away and start again from the basics. Glad you found it.
 
Picking up the ISC this morning. Hopefully that ends this. Stay tuned
 
Not sure why it all the sudden quit working. We shall see.
 
Post up some pictures of your throttle body assembly so we can get a good look at what you have.

And the throttle linkage side of it too.
 
Look like this ????

Screenshot_20210407-090259_Chrome.jpg


Screenshot_20210407-091253_Chrome.jpg
 
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Another test some people talk about to test the 2 throttle body injectors.

Being careful not to drop parts down the throttle body intakes.

Remove the 2 plastc injector cover domes. Then unplug the injector wiring plug from one side, then start it up and see how it runs. Then plug it back in and unplug the other injector wiring plug. Start it up and run and see how that side runs.

Compare how it runs between the 2 sides, if there is a big difference then one of the injectors is plugging off. (or both)

Can pull the 2 injectors out and soak the tips in carb cleaner for a half hour. Blow them out with compressed air, reinstall and try again.
 
George Jets said:
Another test some people talk about to test the 2 throttle body injectors.

Being careful not to drop parts down the throttle body intakes.

Remove the 2 plastc injector cover domes. Then unplug the injector wiring plug from one side, then start it up and see how it runs. Then plug it back in and unplug the other injector wiring plug. Start it up and run and see how that side runs.

Compare how it runs between the 2 sides, if there is a big difference then one of the injectors is plugging off. (or both)

Can pull the 2 injectors out and soak the tips in carb cleaner for a half hour. Blow them out with compressed air, reinstall and try again.
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I will do that as well. I want to take a moment to thank everyone for there help. With how the world is so upside down at times things like this make me forget about all that for a minute. Knowing perfect strangers are taking time and posting to help me. Thanks again.
 
Tried to reset ISC. It still wont retract. Here are some pics
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Yeah the grease in that Idle Air Control is probably all gummed up and hard. The guy in the above video clean out the internal gear drives and relubed them and it worked great.

Unbolt the IAC from the throttle body and it will probably idle right down. Can replace it with a new part from Advance Auto Parts too. (CarQuest)

Edit:
Or did you replace it already? That plunger on there needs to move to allow it to idle down.
It is supposed to engage to speed up the engine when the AC kicks on.

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Might need to put a second throttle return spring on it to pull that IAC plunger back in at idle.

Take some WD-40 and lube up the throttle butterfly pivots, throttle cable, throttle cable and pedal inside the cab too . . (they can stick) and all the mechanical trans kickdown linkages too as they may be hanging up.

Work them back and forth a few times until they are working freely.
 
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Here is some good info on the Mopar IAC (idle air control).
Info starts at 60 seconds:



Notice the Dual Throttle Return Springs.
Can adjust the IAC by screwing the end bolt plunger in or out to fine tune it if it is running to fast.
 
I teplaced it with a new one. It worked for a while then quit just loke the old one. I think its the vomputer tellin it to do what irs doin. I think I foind a bad injector. New on will be here at 1. Stay tuned
 
We all like work-arounds with the problems of the computer controlled cars.

If the IAC and IAC circuit is inactive, that could be a good thing.

Just screw the IAC plunger bolt in or out to manually, permanently set your idle speed to 800 rpm. Run it like that.

If the engine wants to run on (dieseling) when you turn off the key, just put it in drive when turning off the key, that will shut it down.

At least it will run nice and idle nice when it is running.
 
George Jets said:
Another test some people talk about to test the 2 throttle body injectors.

Being careful not to drop parts down the throttle body intakes.

Remove the 2 plastc injector cover domes. Then unplug the injector wiring plug from one side, then start it up and see how it runs. Then plug it back in and unplug the other injector wiring plug. Start it up and run and see how that side runs.

Compare how it runs between the 2 sides, if there is a big difference then one of the injectors is plugging off. (or both)

Can pull the 2 injectors out and soak the tips in carb cleaner for a half hour. Blow them out with compressed air, reinstall and try again.
Click to expand...
I did this test today. Left injector not working. Replaced it. Much better. The ISC will not work. It is new. I took the advice of another menber and backed of the bolt. Running smooth. Havnt test driven yet. Will do tomorrow.
 
Iac failed. Warranty. did you disconnect battery to reset computer?
 
Yes. The battery was disconnected. It might just have to relearn. Test drive tomorrow
 
Both the old and new one wont wotk. Took the old one apart. Nothing wrong with it.
 
Test drive was a success!! The idle speed control is still inop. It may ake some time for the computer to relearn everything. Thanks again to all who helped
 
moparker said:
Test drive was a success!! The idle speed control is still inop. It may ake some time for the computer to relearn everything. Thanks again to all who helped
Click to expand...
Obd1 was crazy for relearn, lots of drive cycles.
If you have access to a manual, perhaps there is a problem in the Circuits to the iac. I doubt it, i would lean more towards a failure of the new part.
 
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