TPS reading at WOT with 1ZZ throttle body?

[4/20 NEVER FORGET]

I recently got a scangauge 2 after having some issues with my 1ZZ throttle body. The issues I am having are idle related, the idle is rarely ever the same. Most of the time the car idles fine at ~700 RPM but some other times ~500, other times ~1200. I can't pin down a reason why it's different when it is, so I got the scangauge to monitor the other things the car was doing.

One thing I noticed that I have a question about: At WOT, the TPS (throttle position sensor) is 81. I know some of you guys have scangauges, what TPS reading are you getting at WOT? (Id be interested to hear answers from stock 1NZ guys as well)

I still might chip swap this throttle body I have. I think it has a lot of mileage on it and swapping it might cure this idle issue I'm having.

[cali yaris]

^ That's correct, 80's max reading for TPS

[4/20 NEVER FORGET]

Well that answers that question. Thanks for the response.

[Astroman]

Him I run the 1zz tb and other than a high idle at first my idle seems normal. I also have a scangauge but the car is still in paint. When I get it back I can verify any readings if you'd like. I'm at 128k miles, put the tb on a couple years ago has worked fine.

[Bluevitz-rs]

idle position should be 11-12%

[Kaotic Lazagna]

Originally Posted by Bluevitz-rs

idle position should be 11-12%

My car has never had an idle position that low. Lowest I'll see it go is 14%, but the idle is still ~550 rpm.

[tooter]

If I'm not mistaken, I believe that it's the factory preset idle screw that determines the idle speed...

...because the same "percentage" for a proper idle with a 1NZ throttle body would be a really high idle on a 1ZZ because the butterfly is so much larger.

[Bluevitz-rs]

I may sound counter-productive but try backing the idle screw off just to see what happens. Just one turn back.

[tooter]

Originally Posted by Bluevitz-rs

I may sound counter-productive but try backing the idle screw off just to see what happens. Just one turn back.

Good advice, Blue.
That did the trick for me when I had the same issue.

[June yaris]

Originally Posted by tooter

Good advice, Blue.
That did the trick for me when I had the same issue.

Where can I find that screw

[Neinris]

It's on one of the corners covered by some sort of glue to prevent it from backing out. You'd have to scrape it off to get access to it. It's an allen screw btw, I forgot what size it was, but mine stripped, to I hammered a torx screw driver into it and was able to back it out. I used blue loctite when I had the 1ZZ TB installed to prevent it from backing out.

My recommendation is, let your engine warm up for a good 10 minutes with the stock TB is still installed, then try to work quickly while the engine is still warm. Turn off the engine every time you make an adjustment. Once you're happy with the idle RPM (mine was set for 650-700rpm), turn off the engine and remove the negative cable off your battery and turn on your high beams to flash your ECM/ECU (I do it this way to remove all the juice from the capacitors in the system).
Even when you get the idle down perfectly, you will still have high RPM during cold starts, but will eventually die down even after about 30 seconds.

I've reverted back to the stock TB due to the rev hang, other than that, I was happy with how peppy it was.

[sh0rtlife]

the rev hang will fix itself outside of "cold starts", the trick is to keep playing with the idle screw and you can eventually get it to be consistent ..its why i loctighted a torx into the screw itself so i can make slight adjustments...at this point tho its settled in and i havnt needed to muck with it

for referance the idle screw DOSE NOT adjust the stop point or the butterflys position, it changes the "tension" on the butterfly and the electric motor to hold open or hold closed the butterfly, so you cant treat it like a true idle adjustment....once you understand that your changing the positive/negitive "spring load" on the motor zero point it starts to make more sense as to why some adjustments do NOTHING.

the cars ecu ultimately tells the TB motor how much "load" is acceptable to maintain ilde, so with the screw you can add or remove load but its not a linear adjustment and is best made after taking it for a drive

[Neinris]

Originally Posted by sh0rtlife

the rev hang will fix itself outside of "cold starts", the trick is to keep playing with the idle screw and you can eventually get it to be consistent ..its why i loctighted a torx into the screw itself so i can make slight adjustments...at this point tho its settled in and i havnt needed to muck with it

for referance the idle screw DOSE NOT adjust the stop point or the butterflys position, it changes the "tension" on the butterfly and the electric motor to hold open or hold closed the butterfly, so you cant treat it like a true idle adjustment....once you understand that your changing the positive/negitive "spring load" on the motor zero point it starts to make more sense as to why some adjustments do NOTHING.

the cars ecu ultimately tells the TB motor how much "load" is acceptable to maintain ilde, so with the screw you can add or remove load but its not a linear adjustment and is best made after taking it for a drive

My Dee Dee is a manual, the rev hang I'm talking about is when I shift gears. There's about a second or two delay that the engine is still revved up even if the throttle pedal is fully released and the clutch pedal is fully pressed.

The screw does change the spring load, but it also DOES adjust the stopping point of the butterfly. It's the same principle as a single stage height adjustable suspension, where you adjust the spring perch to adjust the height ride. I don't have the 1ZZ installed right now, and I can tell that when I turn the screw, the butterfly's opening either get bigger or smaller when I adjust it.

[sh0rtlife]

Originally Posted by Neinris

My Dee Dee is a manual, the rev hang I'm talking about is when I shift gears. There's about a second or two delay that the engine is still revved up even if the throttle pedal is fully released and the clutch pedal is fully pressed.

The screw does change the spring load, but it also DOES adjust the stopping point of the butterfly. It's the same principle as a single stage height adjustable suspension, where you adjust the spring perch to adjust the height ride. I don't have the 1ZZ installed right now, and I can tell that when I turn the screw, the butterfly's opening either get bigger or smaller when I adjust it.

i thought it did too till i had the unit apart and played with it without the spring installed..its got no "stop" in it its 100% motor tension on it

i wonder if your rev hang is "board" issue..could also be a worn out spring for that matter as the spring is the only thing that brings the butterfly shut

[Calrenman]

Originally Posted by sh0rtlife

i thought it did too till i had the unit apart and played with it without the spring installed..its got no "stop" in it its 100% motor tension on it

i wonder if your rev hang is "board" issue..could also be a worn out spring for that matter as the spring is the only thing that brings the butterfly shut

Hello Short,

Are you running a 1zz? I am thinking of doing this mod.

I am wondering how the 1zz effects fuel efficiency and if the torque is increased? If it helps my car up hills without too much of a fuel use penalty I wish to give it a shot.