Sticky Throttle

I would remove the intake and throttle body and inspect each separately for binding. I would clean up the throttle butterfly with carb cleaner and a small rag and see it improves. If it doesn’t  I would replace the throttle body with a used low mileage and new IAC valve. 

Before motor install, I cleaned everything intake-wise to spotless, put a dab of graphite on moving joints and on install and now it operates smoothly without any obvious binding. The idle air control valve was cleaned and I poured a series of cleaners through it thinking that would clean it. Interestingly while it looked spotless, it has the fluctuating idle over 15mph and a standing idle of 1500. Most of the time. I’ll have to take some time and take everything apart and replace the IACV with a cleaned up 1zz that resides on a motor in my garage.  

I honestly do not understand the rash of 2zz IACV that stop working properly or bind. I speculate that it is a function of buying Japan raised low mileage 2zz where the fuel has less detergent than US fueled cars and they probably don’t do many Italian tune ups.

It could just be the IAC valve. I’m on my original and at one time it was a bit lazy. Before I decided to replace it I would add some MAF sensor cleaner in the hole the throttle body that feeds air to the IAC valve and let it soak overnight, it would run horrible for a few days and then work well to stabilize idle.  I did repeated cleanings at the start of every year for two subsequent years and stopped.  The years after that it is working better then I have seen it. It catches the ideal well and is stabilized. When there is electrical draw it will bump up by 100 rpms and settle down and stabilize like a new IAC valve. The only thing I can think of is this coincides with my luck is the Lithium battery around 2017. 

@ispy 

Do your throttle get stuck closed after going WOT?

@scotched

No just normal driving. Let's say drive normally then stop at a light then put in gear... Throttle stiff. Kinda confusing but gotta go... Push harder (but not stomping) it clicks like it moved back in line, then releases and back to normal free movement. Maybe happens once in 5 days driving. I thought it was loose throttle cable that was coming partly out of the retainer but not enough to actually come off. 

How is your throttle cable routed?  I'd make sure there aren't any sharp bends or anything.  With the angled 22Z manifold the cable can be close to the top shelf of the engine bay sometimes as well.  Make sure you have clearance there.

Drove a buddies 7th gen Corolla with a 20V Blacktop swap. The throttle cable is meant for RHD cars and on a LHD car it's routed very odd. His throttle pedal wasn't very smooth and got a bit sticky. So good call nocoolname.

@ispy

There's a thread on SC (I can't find the bookmark) where the sticky throttle ended up that the throttle adjustment screw was jagged and caused the pulley wheel to sit on it funny when throttle was closed. 

Thanks for input. Hopefully this weekend I’ll play with it. Scotched, this one?: https://www.spyderchat.com/threads/2zz-throttle-position.100665/#post-1468441 wherein it you state: “From my experience, the cable on my 2zz (angled matrix throttle) has to be routed in such a way that it does not stick.”

and then

”My pedal was sticking a bit in the fully closed position. I'd have to sometimes give a good jab on the throttle pedal to release it.
I've solved that, it was a bur on the "home position" screw adjuster and also by lubing up the return spring etc.”.

I’ll update in time.

@ispy

Yea that's the thread.  Some pics in the bottom of the thread.

The gas pedal is one of the worst parts on this car IMO.

The problem could be everything from the cable, the throttle, or the pedal itself.

Well, I played with the throttle cable yesterday.  My 2zz is from a Corolla or Matrix. The sticking throttle occurs intermittently. I looked the cable as it entered the top of the throttle body.  The cable 'bends' back to correct for the throttle body angle in a narrow space. It seems that when I had adjusted the cable to check to see if it was too tight I loosened the nuts, cleaned and greased the threads then reinstalled the cable in its 'craddle'. The problem is that I did it from below and did not seat the cable as far back as possible. This lead to the cable not fully clearing the vacuum line (steel) the function of which escapes me, but I think it is a breather for the fuel tank.  I loosened the bracket that holds this line and pushed it back toward the firewall and bent it up to maximize the clearance from my throttle cable. With the cable fully seated toward the back and the lines bent and re-positioned, the cable is clear.  I did not get a return (yet) of the sticking pedal. When I get the chance to crawl under, I'll look into the screw binding just because I'm curious...and the problem is intermittent.

The sticking may still occur but not so bad and only a little once in 4 days of driving. Interestingly, since last post I went to check my Idle Air Control Valve with a borrowed IACV controller. (My symptoms was a 1600 idle, slightly bouncing idle over 15 mph between shifts or clutch pedal in.) A little bit of a pain to figure how to disconnect and free the harness connector, especially with the car warm. It was a solid connection. The controller didn’t fit (4 wire vs 3 wire). So I reconnected the IACV and put away my toys. Later when I drove, I noticed the idle was normal (950) and the wavering between shifts was dramatically less. The connector? Maybe that’s why the issues I had with the idle were not exactly what one typically sees with a dirty or failing IACV. A nice relief and interesting. I put this here due to it being a bit of an oddity. Just to qualify, I had cleaned the IACV and throttle body when motor was out.  Every connector was checked, cleaned and the harness was removed and re-wrapped with liquid tape, silicone heat resistant electrical tape and Tessa tape.