88 1500 5.0 throttle sticking closed

[badco]

Th350 has a kick down cable stock, the vacuum works the modulator. Th400 has a switch on case that works what would be kick down.

So the idle screw should have cracked it open enough to not hang even if shaft is worn

 

[Greg S Meier]

Th350 has a kick down cable stock, the vacuum works the modulator. Th400 has a switch on case that works what would be kick down.

So the idle screw should have cracked it open enough to not hang even if shaft is worn

Huh.
This only has 1 piece of linkage attached to the tb.
Electric?

 

[Pinger]

I backed the idle screw out on mine today. The throttle resisted initial opening. I screwed it back in and it's fine. Just saying.

 

[PlayingWithTBI]

Yep, I had it where, if you back out the screw too far the inner sleeve hooks on to the outer sleeve and makes it hard to depress the pedal. Here's my bored out 46mm with "Ultimate Mods" including shaved throttle shaft. I don't know if you can see it well enough in this pic but the blades are closed all the way. It relies totally on the IAC to control idle.

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[smdk2500]

I backed the idle screw out on mine today. The throttle resisted initial opening. I screwed it back in and it's fine. Just saying.

Isn't yours a vortec though? Or am I thinking of someone else.

 

[Pinger]

Isn't yours a vortec though? Or am I thinking of someone else.

Correct - and I forgot to mention that.
But, the principle appears to be the same.

I checked mine yesterday because of what I'd read in this thread and didn't like the idea that the butterfly resting on the throttle body was the final stop and not the designated screw.
And was prompted to think it could have been as I'd messed around with it earlier (and the lock on it was already missing at that point) when I had a couple of occasions where the idle settled at 1500 rpm and wouldn't budge so thought it worth rechecking.

It's awkward as hell as the IAC seems to compensate, I couldn't read the tach, and hearing what's going on above the racket of the fan makes detecting rpm change difficult.
In the end, I wound it out , heard the rpm drop, experienced the sticking, wound it back in just enough for the rpm to rise a touch, checked the sticking was gone and quit there.

 

[Greg S Meier]

I backed the idle screw out on mine today. The throttle resisted initial opening. I screwed it back in and it's fine. Just saying.

When you screwed it back in did you go past the stock setting of the idle & raise it then go back down?

 

[Pinger]

When you screwed it back in did you go past the stock setting of the idle & raise it then go back down?

My stock setting as far as I'm aware was lost either by me previously or more likely before that - the security cover was missing and mine is converted to LPG and there's been some dubious modifications.
But yes I went up initially (to close any gap between the screw and its stop) - but everytime I did the rpm dropped very quickly again - the IAC at work presumably.

If I were you I'd screw it in until the sticking has stopped and if the IAC isn't controlling the idle at an acceptable level either seek advice as to how to achieve that (ie ask the guys here who know this stuff and can 'reset' the IAC) or accept that your throttle body is beyond reclaiming. Mine BTW has only 40,000 miles on it, no wear and still 'stuck' with the screw wound out. Incidentally, 'stuck' for me was resistance to opening it by hand at the linkage and may not have been noticeable at the pedal but it shouldn't be sticking it all IMO. It wasn't before.

I'll be driving it tomorrow and if there's any weirdness about I'll let you know. Just shunting on the driveway yesterday it was fine but not up to full operating temp.

 

[Greg S Meier]

My stock setting as far as I'm aware was lost either by me previously or more likely before that - the security cover was missing and mine is converted to LPG and there's been some dubious modifications.
But yes I went up initially (to close any gap between the screw and its stop) - but everytime I did the rpm dropped very quickly again - the IAC at work presumably.

If I were you I'd screw it in until the sticking has stopped and if the IAC isn't controlling the idle at an acceptable level either seek advice as to how to achieve that (ie ask the guys here who know this stuff and can 'reset' the IAC) or accept that your throttle body is beyond reclaiming. Mine BTW has only 40,000 miles on it, no wear and still 'stuck' with the screw wound out. Incidentally, 'stuck' for me was resistance to opening it by hand at the linkage and may not have been noticeable at the pedal but it shouldn't be sticking it all IMO. It wasn't before.

I'll be driving it tomorrow and if there's any weirdness about I'll let you know. Just shunting on the driveway yesterday it was fine but not up to full operating temp.

I did screw it in. It raised the idle to high.

 

[Pinger]

I did screw it in. It raised the idle to high.

Without re-reading the entire thread.... was there not an IAC workaround to compensate?
Again, without re-reading the entire thread, did you try a different (or new) throttle body?

When I was messing with mine yesterday I wasn't looking to replicate your problem (only to ensure that it was 'stopped' on the proper stop). But the same problem you have appeared.

Again, without re-reading the entire thread, did screwing it in at least rid you of the sticking problem?