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-   -   Throttle always sticks a bit DOHC (http://www.saturnfans.com/forums/showthread.php?t=264546)

SLfun 01-07-2020 01:06 PM

Throttle always sticks a bit DOHC
 
So ya, the throttle on my SL has always been a bit sticky off idle, esp in the colder weather. I have serviced it several times, usually by just removing the intake tube and scrubbing it out with a toothbrush and solvent, sometimes I remove the TB and thoroughly clean it.

It's usually fine for a bit, but lately it gets sticky again sooner and sooner without really getting that dirty inside. Is there some other adjustment I can make? Runs fine otherwise.

trottida 01-07-2020 01:34 PM

Re: Throttle always sticks a bit DOHC
 
Could it be the throttle cable that is sticking?

SLfun 01-07-2020 01:50 PM

Re: Throttle always sticks a bit DOHC
 
[QUOTE=trottida;2338592]Could it be the throttle cable that is sticking?[/QUOTE]

Checked that, it's not. I think it may be that the throttle plate is binding in the bore a bit, a result of my coming off the gas real quick when I shift for years causing the throttle to slam shut 1000's of times? :p
Was wondering whether I should perhaps use the stop screw to adjust it a tad....

fetchitfido 01-07-2020 03:02 PM

Re: Throttle always sticks a bit DOHC
 
It sticks because the engine burns oil and the PCV valve pulls the oily mess back into the intake which coats the throttle plate in oily goo.

Don't mess with the stop screw, it's more annoying than it's worth to get the idle back where it belongs if you do.

You can try one of those fixed orfice PCV valves and see if that helps extend the time between cleanings.

Waiex191 01-07-2020 03:03 PM

Re: Throttle always sticks a bit DOHC
 
Don't adjust the screw. Easy enough to pop the throttle body and either clean or replace it.

fdryer 01-07-2020 03:41 PM

Re: Throttle always sticks a bit DOHC
 
The factory adjusted throttle stop screw never closes the throttle plate. If you examine your throttle you should see it slightly opened unless someone before you misadjusted it. It's never fully closed at any time.

Adjusted from the factory, throttle plate opening with the bypass air port blocked off is set for 500-600 rpm. You'll never be able to adjust the throttle stop screw unless the bypass air port is blocked, the hole in front of the throttle plate that allows air to bypass the throttle plate. Bypass air flows thru Internal passages to the idle air control valve where its controlled by the pcm. The pcm adjusts the iacv for idle rpm for electronically controlled idle, not the throttle stop screw. And if you are observant, the difference between blocked bypass port/throttle stop screw idle and final idle being higher is the supplemental air controlled by the iacv for idle.

SLfun 01-07-2020 07:57 PM

Re: Throttle always sticks a bit DOHC
 
So I had a closer look and indeed the throttle plate was mechanically binding in the throttle bore. The plate has worn a grove in the bore and the plate is getting stuck in it.

I know it's ill advised, but the only way I could fix it was to tighten the throttle position stop screw. With a quarter turn the throttle moves freely now since the plate no longer gets stuck in the bore.

The idle has barely changed, maybe it's gone up 50-100 rpm? Does not matter too much for me since the car is manual.

I'll be scanning the junk yards for another TB. For now the car runs much better.

fdryer 01-07-2020 08:43 PM

Re: Throttle always sticks a bit DOHC
 
In the real world, nothing is ill advised when you have to do things not recommended to make things work. There's the book and reality.

All the men and women in NASA's space program including every subcontractor never anticipated when Apollo 13 blew up its liquid oxygen tank while performing a routine stirring operation to gauge levels. A simple routine with internal tank wiring burned years earlier and going unannounced without a clue to danger occurred at the worst time possible. NASA and engineers worked day and night to create a way to bring home three astronauts leaving for the moon and returning in one piece. The phrase "failure is not an option" befits a crisis no one can anticipate.

Your adjustment to crack open throttle a little more is probably well within the adjustment margin for the pcm to accommodate it by automatically readjusting the iacv. While not discussed much, the pcm in my opinion has the ability to adjust for wear and tear like the groove worn into the throttle bore.

As long as idle and overall engine running hasn't changed drastically, you may not have to buy a replacement throttle body.

trottida 01-07-2020 08:52 PM

Re: Throttle always sticks a bit DOHC
 
[QUOTE=SLfun;2338628]

I'll be scanning the junk yards for another TB. For now the car runs much better.[/QUOTE]



LOL - I have one. I should have just shipped you then carcass of my parts car.

Waiex191 01-07-2020 08:56 PM

Re: Throttle always sticks a bit DOHC
 
[QUOTE=trottida;2338632]LOL - I have one.[/QUOTE]
I can see more bootleg parts crossing the border!

trottida 01-07-2020 09:16 PM

Re: Throttle always sticks a bit DOHC
 
[QUOTE=Waiex191;2338633]I can see more bootleg parts crossing the border![/QUOTE]

Nah, he's from Ontario. I'm slowly unloading my parts bins into his 98 Sedan one shipment at a time. Canada Post is winning; making more money than me.


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