2006 GT Replace TPS w/o replacing throttle body?

[JanetsVibe]

Before I start digging into my engine, I was hoping to get some clarification.

I bought a new TPS, and have been getting conflicting information on if I can actually replace it alone or if I have to replace the entire throttle body. (New throttle body is about $700 and there are none to be found in the local junk yards.)

In the very least, I will have to take the throttle body off the engine because the TPS is located inside of it. (So sad to watch the youtube videos of other cars where it is simply screwed onto the outside of the throttle body.)

Note to self: next time, buy the more common car option: there are way more parts to be found for it at the junk yard.

Thanks!

[jolt]

It does bolt to the side of the throttle body and the bolts get tightened to 18 in-lbs. on both the 1zz-fe and the 2zz-ge engines.

INSTALL E.F.I. THROTTLE POSITION SENSOR
(a) Check that the throttle valve is fully close.
(b) Insert the throttle position sensor to the throttle body with it turned clockwise by 30 degrees to 90 degrees against the fully close valve position.
(c) By turning the throttle position sensor clockwise, tighten 2 screws.
Torque: 2.0 N-m (20 kgf-cm, 18 in.-lbf)

Just mark everything before you take it apart and/or take pictures so you have a reference to see how it goes back together. Now is also a good time to clean your idle speed control valve assembly while you have the throttle body off.

[JanetsVibe]

Thanks Jolt,

I'll start getting in there tonight.

The Haynes Manual says: "On 2005 and later engines, the throttle body is operated by an electric throttle control motor instead of a cable. On these models, the TPS is part of the throttle motor assembly and cannot be replaced separately. If there are problems with the throttle control motor or the TPS, the complete throttle body must be replaced."

But then it doesn't specify the 1ZZ or 2ZZ engine.

And why would the parts store sell me a TPS if I couldn't replace just that? On the other hand, the set of directions they gave didn't mention removing and installing a new TPS, just the throttle body itself. But I imagine when I get it off in my hands, I'll be able to see where it goes and how to replace it.


Janet

[jolt]

Around 2006 is when the change over to "drive by wire" took place. If your engine has a throttle cable then the TPS can be changed out as per above.

If your throttle body does not have a throttle cable hooked to the throttle body and is controlled by electric wires only, then the TPS controls are part of the throttle body and can not be changed out. A throttle body for a "drive by wire" is around $700.00 and up.

What was the trouble code from the ECM? Why do you want to change the TPS? A good cleaning of the throttle body and ports is the best place to start when you have idle problems. Also vacuum leaks can cause idle and check engine problems.

[JanetsVibe]

Oh Jolt, that is the best news I've heard in a week. I should have read closer. My car does have a throttle cable. Hurray!!!

My problems with stalling started 3 years ago - the day after I got the clutch replaced - but that seems to be a coincidence. It stalled sometimes when I was slowing down (I assume because I wasn't giving it gas - and it wasn't because I was stalling the car.)

Then the error code for the secondary air injection system came on, then went away with other problems since. (Error code: P2445) (I'll get back to that later)

Spent hundred of dollars at (not GM) mechanics where they couldn't tell me the problem. But we ruled out a lot of options.
- Probably not the fuel pump because I don't have lack of power
- Not a vacuum leak (at least a couple years ago they were fine)
- Not backup pressure due to crushed pipes.
- Tug test on wires said they were fine.
- I cleaned out the throttle body and it still continued to stall.
- Not bad gas
- Compression in the engine is good.(currently decent 160 - 165)

I took a mechanics course at the local community college to try to figure it out. The instructor was a GM mechanic and said it was probably the computer or IAC. But there was no way of knowing. If it was the ECM, then the error code thrown for the secondary injection system makes sense, if the computer was not working properly.

So I drove it for the next few years and it continued to stall intermittently.

Last week, it wouldn't start unless I floored the gas. I hadn't driven the car in a couple days and it was cold, but I never had that problem before. Then after work, I turned on my car to find the check engine light, with a high idle (2K). Got the error code (P0122 TP Sensor Circuit Low Voltage). The check engine light went off, but I am still having idling problems.

So between changing out a $65 TPS or getting a new computer, I opted for the TPS. Until I thought I had to replace the whole throttle body. Then I quite sadly started looking to buy another used vibe (and even sadder - a matrix). My vibe has 207K on it, and I need to it be reliable to get to work. It might be time...

I haven't started working on my car yet, do you recommend that I bring it to the dealer for diagnosing? Skip the diagnosing, and just replace the TPS, or go look at that horrid baby blue 2003 Matrix that is for sale?

Thanks a million for the help here.
Janet

[vibrologist]

Janet, there was a recall for the PCM computer. Find out if your car was included and if the recall was performed. A GM dealer should be able to help with that.

[JanetsVibe]

I wish the recall was for my engine. Sadly it is not.

I can't get into GM until Monday, so I decided to just replace the TPS and see if that works. But had to stop because New Years, so I will finish tomorrow. I got stuck on taking the throttle cable off, it doesn't seem to be designed to come off, I think I'll just leave it on and carefully hold the throttle body to the side still connected to it while I get at the TPS.

Thanks again for the help. Happy New Year!

[jolt]

So the real problem is the engine stalling out or to low of an idle speed.

This is information for a 2003 Toyota Corolla/Matrix. Most of it is the same through 2008, http://madstyle1972.com/Repair/

Look at section 05-190, 05-195, 05-264, also 10-15, and 10-16.

And something else to read: http://repairpal.com/obd-ii-code-p0122

Make sure that the engine has a good electrical ground. You can never have to many grounds so to make sure the engine is grounded, add another ground wire from throttle body to the negative side of the battery. Dirty or bad electrical connections? Do you have Air Conditioning and having the air on or off make a difference with stalling?

[Salsa Guy]

OK the 06 VGT is Drive By Cable and don't believe it was subject to the PCM recall. There is an idle set screw on that TB you can adjust to raise the idle. However I'm wondering if your IACV maybe plugged. Yes the TPS can be changed easliy.

FYI the 03-06 VGT/XRS 2zz and AWD 1zz where drive all by cable. Although they changed the ECU pinouts on the 05-06 VGT but believe all the sensors and actuators are the same.

[JanetsVibe]

Ooh, the repair manual! Fantastic. I saved the link.

A/C didn't have a difference with the RPMs to the car. If it did, then I would suspect the idle speed control circuit. (Or at least that is what my old research showed it out be...)

My current problem is high RPM, and the old problem was intermittent stalling. Check engine light going on and off.

So I just finished replacing the TPS. (that was the last error code that was sent). And no change. Still wandering idle up to 2K RPMs.

I'm going back to my gut feeling of it is the engine computer. In any case, I have an appointment with GM in the morning. Past mechanics haven't been able to figure this one out, but I hope bringing it to GM will help. And once I get it in decent shape, I am going to look to trade it in for a non-GT vibe with lower miles.

[circuitsmith]

Have you cleaned the idle air control valve (IACV)?
It's also located on the throttle body assembly.

[jolt]

"Now is also a good time to clean your idle speed control valve assembly while you have the throttle body off."

To slow, now to fast; this is the one item that can do both. Make sure it is free and clean as circuitsmith also pointed out. Go to this page and scroll towards the bottom of the page where the pictures start. This shows a good breakdown of the valve.

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