03 GT heavy / jerky throttle

1.8-liter VVTL-i (2ZZ-GE) and VVT-i (1ZZ-FE) engine, transmission, exhaust, intake, and performance tuning discussions
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small03GT
Posts: 3
Joined: Fri Oct 22, 2021 6:05 am
Location: Olympic Peninsula, WA

03 GT heavy / jerky throttle

Post by small03GT »

Just picked up an '03 GT for 2k a few months ago as a daily driver / beater. 200+k but it was towed behind a motorhome for most of its life and is in really good shape overall.

But, I have two problems that I have not been able to find answers to yet, and I've tried searching the forums here and online.

1. At low speeds in gear, the car is jerky on/off throttle. Say you're creeping along in second at 15 mph on a side street - let off the throttle and the car jerks, back on and the car jerks. This does not happen at higher speeds / gears. And, it's made worse by problem #2.

2. The gas pedal / throttle is heavy and almost feels like it gets caught on something when starting from a stop. It's nearly impossible to shift smoothly in lower gears. This is the first car I have owned since I learned to drive that I have stalled with some regularity when starting from a stop, and I've had a fair few manual transmission cars. My old Toyota pickup is smooth as buttah by comparison, and my wife's 51 Chevy truck shifts more easily.


Here's what I've had done so far: Full inspection by mechanic, tire check and rotation, brakes and suspension check (all good), tested throttle action and lubed throttle cables (2), tested and cleaned throttle body and IACV, checked pedals for physical issues (none), new rear O2 sensor, Engine code check and clear.
Currently has a P1693 Code so the vvtl-i system isn't working, but I don't think it's related.

There are two things I'm wondering about:

1. There are two throttle cables on this car that connect each side of the cruise control module. Could that somehow be causing part of the problem? They were checked and seem to be functioning fine. I did see a small improvement with lubing the cables - maybe I should replace them entirely?

2. There are 3 return springs on the throttle body. My mechanic suggested removing one of them to reduce the spring pressure a little bit. Thoughts?

I really like this little car, but driving it around town is so annoying that I'm contemplating dumping it for something easier to drive.

Thanks so much GenVibe community for any help you can provide!
jolt
Posts: 945
Joined: Sun Mar 02, 2014 2:07 am
Location: Twin Cities, Minnesota

Re: 03 GT heavy / jerky throttle

Post by jolt »

I would have said to clean the throttle body because the butterfly is sticking in build up gunk inside the throttle bore, but I see you said that was already done. I would then check the throttle bore where the butterfly would come close to making contact with the bore at idle. There should not be any contact between the butterfly and the throttle bore. If there are any signs of contact, then that is your problem. If the throttle body is worn where the throttle shaft goes into the body, this will allow the butterfly to hit and stick in the bore of the throttle body. Also if someone adjusted the throttle stop screw, it can cause the same damage and the same sticking of the throttle. Some people turn this screw trying to use it to adjust the idle speed of the engine, which it is not to be used for.
You have hit all the issues of a worn throttle body and removing a spring is one of the things people have tried, but that does not fix the problem of a worn throttle body, and it may cause safety issues with the car if one of the springs is removed. If that spring was not required for safety, Toyota would not have spent the money to put it on the engine.
tpollauf
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Re: 03 GT heavy / jerky throttle

Post by tpollauf »

First off WELCOME to GenVibe :D Secondly, finish filling out your profile showing location! I say this because if you're in the rust belt areas of the country where salt/brine eat up our cars, you could have corrosion issues contributing to your problems. Thanks ;)
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2009 Vibe GT (manual), 2009 G8Gt, 2009 Vibe GT (auto)
2014 Silverado, 2004 Vibe GT

"everything is modifiable"
small03GT
Posts: 3
Joined: Fri Oct 22, 2021 6:05 am
Location: Olympic Peninsula, WA

Re: 03 GT heavy / jerky throttle

Post by small03GT »

Thanks tpollauf, I have updated my profile to include my location in sunny western washington! No rust on the car, it has lived it's whole life in puget sound.
Thanks Jolt, that is also the culprit my mechanic suggested. In early January he removed one of the three throttle springs, and re-checked and cleaned the throttle body. He didn't mention seeing any worn parts.
Just got back from a 2500 mile road trip, and the throttle is noticeably better but still a PITA compared to any other manual I have had. Ran a can of STP injector cleaner through the first couple of tanks of fuel on the trip.

I have not closely inspected the TB myself for wear. Going to do an oil change to synthetic, maybe flush transaxle?

Also, the shifter action absolutely sucks, which I understand can be improved with brass shift bushings, so will try that as well.

Returned about 32mpg average freeway mileage at 72 mph, which seems about right with 250lbs of humans and another 100+ lbs of stuff along for the ride.
My mechanic said an aftermarket TB doesn't exist; can you refurbish a stock one with new parts?
Bookworm
Posts: 764
Joined: Fri Nov 05, 2010 11:21 am
Location: Houston, TX

Re: 03 GT heavy / jerky throttle

Post by Bookworm »

You could certainly grab one off of a car with lower miles out of a salvage yard, and clean it thoroughly.
jolt
Posts: 945
Joined: Sun Mar 02, 2014 2:07 am
Location: Twin Cities, Minnesota

Re: 03 GT heavy / jerky throttle

Post by jolt »

Here are a couple of possibilities, depending on what you need repaired and what you have to work with:

https://www.monkeywrenchracing.com/prod ... zz-ge-new/

http://maxbore.com/index.html

These links were posted on this board in a different thread. Use the search and you may find more.
Phoneman
Posts: 29
Joined: Fri Jan 08, 2021 9:54 pm

Re: 03 GT heavy / jerky throttle

Post by Phoneman »

small03GT wrote: Wed Feb 09, 2022 6:50 am
Also, the shifter action absolutely sucks, which I understand can be improved with brass shift bushings, so will try that as well.
The shifter on my 03 GT sucked really bad too when I bought it in Dec. of 20. It was very vague and had me considering an aftermarket shifter.

I purchased a set of solid aluminum shifter mount bushings from MWR last spring and installed them. It gave the shifter a more precise feel.

I had also ordered a set of the MWR brass shifter bushings but only recently had them installed.

The combination of the two sets of bushings really smoothed up the shifter action and made it feel even more precise.

It's still not a great shifter but I can now live with it without feeling the need for an aftermarket shifter.


Replacing both sets of bushings is a cheap and effective way of improving shifter feel.
2005 Vibe - 240k
2003 Vibe GT - 117k (totaled)
2003 Vibe GT - 117k
tpollauf
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Joined: Wed Jan 20, 2010 11:37 am
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Re: 03 GT heavy / jerky throttle

Post by tpollauf »




I purchased a set of solid aluminum shifter mount bushings from MWR last spring and installed them. It gave the shifter a more precise feel.

I had also ordered a set of the MWR brass shifter bushings but only recently had them installed.

The combination of the two sets of bushings really smoothed up the shifter action and made it feel even more precise.
So the aluminum bushings are for the shifter inside the car, and the brass ones for the shifter forks on the tranny? My 2004 Vibe Gt has the same problem that apparently lots of higher mileage GT's have, with lots of play and sloppy shifting.
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2009 Vibe GT (manual), 2009 G8Gt, 2009 Vibe GT (auto)
2014 Silverado, 2004 Vibe GT

"everything is modifiable"
Phoneman
Posts: 29
Joined: Fri Jan 08, 2021 9:54 pm

Re: 03 GT heavy / jerky throttle

Post by Phoneman »

tpollauf wrote: Wed Feb 23, 2022 8:29 pm



I purchased a set of solid aluminum shifter mount bushings from MWR last spring and installed them. It gave the shifter a more precise feel.

I had also ordered a set of the MWR brass shifter bushings but only recently had them installed.

The combination of the two sets of bushings really smoothed up the shifter action and made it feel even more precise.
So the aluminum bushings are for the shifter inside the car, and the brass ones for the shifter forks on the tranny? My 2004 Vibe Gt has the same problem that apparently lots of higher mileage GT's have, with lots of play and sloppy shifting.
Yes

The solid aluminum bushings replace the rubber and stamped steel OEM bushings that mount the shifter to the console.

They made the biggest difference by making the shifter feel more precise.

The brass bushings replace the rubber and stamped steel OEM bushings at the shifter forks on the transmission and have made shifting feel smoother.

I have been pleasantly surprised at how less than $50 worth of parts have transformed the shifter from vague and sloppy into a decent shifter feel.
2005 Vibe - 240k
2003 Vibe GT - 117k (totaled)
2003 Vibe GT - 117k
tpollauf
Posts: 4025
Joined: Wed Jan 20, 2010 11:37 am
Location: Toledo/Oregon, Port Clinton Ohio
Contact:

Re: 03 GT heavy / jerky throttle

Post by tpollauf »

Thanks for the reply. Just ordered the set(s) from MRW. I'll post results next week when I get them and have the time to change them out! :D
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2009 Vibe GT (manual), 2009 G8Gt, 2009 Vibe GT (auto)
2014 Silverado, 2004 Vibe GT

"everything is modifiable"
tpollauf
Posts: 4025
Joined: Wed Jan 20, 2010 11:37 am
Location: Toledo/Oregon, Port Clinton Ohio
Contact:

Re: 03 GT heavy / jerky throttle

Post by tpollauf »

Wow that was quick. Just ordered these over the weekend and got them today! :D Now I have a weekend project planned ;)

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2009 Vibe GT (manual), 2009 G8Gt, 2009 Vibe GT (auto)
2014 Silverado, 2004 Vibe GT

"everything is modifiable"
Bookworm
Posts: 764
Joined: Fri Nov 05, 2010 11:21 am
Location: Houston, TX

Re: 03 GT heavy / jerky throttle

Post by Bookworm »

tpollauf wrote: Tue Mar 01, 2022 1:59 pm Wow that was quick. Just ordered these over the weekend and got them today! :D Now I have a weekend project planned ;)
Like you didn't have enough to do already? 'Honey, would you do this?'
small03GT
Posts: 3
Joined: Fri Oct 22, 2021 6:05 am
Location: Olympic Peninsula, WA

Re: 03 GT heavy / jerky throttle

Post by small03GT »

Great info! Yes, I plan to do the shifter bushings soon.

Update: I finally changed the oil after our road trip, full Syn, and got to cleaning the VVTL-I lift screen as well.
Afterwards, I noticed a few things:
1. The shifter action is much better after the oil change, not sure why. I still plan to do the bushings when I get a chance.
2. While I had the intake boot and assorted emissions hoses off to clean the lift screen, I played around with the throttle body action. It's clean as a whistle (paid mechanic to clean so I would hope so) BUT! There is some binding when opening the throttle from closed - like right about 1/8 open I feel it bind up a bit. So, I'm guessing that contributes to the jerky throttle.
3. I also suspect the IACV was not cleaned, as I have some idle issues, sometimes dies when coming to a stop after being on the highway, takes a while to settle when clutch pushed in, etc...

I'm going to clean the EGR, put in a new PCV valve, and get to the VVTL-I timing side screen to clean that next.
Maybe tackle cleaning the IACV after that.

I feel pretty confident the TB is the culprit, which points to purchasing a new TB at $500...Yuk. Cheap cars aren't always so. There are no junkyards around my area at all, let alone ones with Vibe GTs in them.
I looked at MWR and Maxbore, but it seems that if I need a new IACV I'm better off buying a whole new unit than have it rebuilt.

Opinions welcome!
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