Rebuilt Throttle Body myself and now have high idle

[4gfun]

I decided to follow one of the procedures to rebuild the throttle body using milspec seals. There are no boost leaks on the throttle body.

When I was rebuilding the throttle body, I carefully marked how I took it apart and then like an idiot cleaned it up with throttle body cleaner forgetting that I marked it.

I would like to know which parts would cause an issue if installed backwards.

I know the throttle plate can be installed incorrectly, but what about the throttle shaft? As long as the ends of it go to the throttle cable and the TPS I don't see how that could be wrong.

What else could be wrong? I etched markings into the throttle plate before installing it so I think that would be right.

The car idled just fine before I started the rebuild (due to leaky shaft seals).

TPS is set at 10% per MMCD.

The throttle plate doesn't stick and is fully closed. The BISS screw doesn't leak and is fully in like it was before I rebuilt it. I never went into the FIAV either.

Thanks

 

[snowborder714]

As long as you have the countersunk bolt hole side of the shaft away from the intake manifold flange, you have the shaft installed correct. I assume you'd be smart enough to put it in from the correct end so the TPS is usable.

Did you adjust the idle position switch properly?
Did you make sure the throttle plate sealed properly? And that it was installed properly (small dashed lines above the shaft towards the throttle body elbow)?
Did you adjust the throttle cable if necessary?

 

[4gfun]

Ok, thanks for the info...

Going down the list you provided.

as far as the throttle plate goes...do you mean the circled dashes (sorry I couldn't get a good picture)? In this case they face the throttle body elbow, but are the dashes also supposed to be on the top (vacuum port area) of the throttle body?

Thanks

As long as you have the countersunk bolt hole side of the shaft away from the intake manifold flange, you have the shaft installed correct. I assume you'd be smart enough to put it in from the correct end so the TPS is usable.

Did you adjust the idle position switch properly?
Did you make sure the throttle plate sealed properly? And that it was installed properly (small dashed lines above the shaft towards the throttle body elbow) like they are in the pic?
Did you adjust the throttle cable if necessary?

 

[snowborder714]

Yep, that's what I meant about above the shaft.

 

[4gfun]

Yep, that's what I meant about above the shaft.

Ok...I can rule that one out...and the throttle shaft direction etc....

Thanks!

Throttle body cable disconnected to rule out the problem as well.

The only things that are left in my viewpoint are:

1) Throttle body didn't stick last night, but it is starting to BARELY stick when I begin to open it.

2) If the TPS is backwards, what are the symptoms?

3) One arcticle says that you are supposed to see even light all away around the TB while another says that you are supposed to see none...I can't imagine not being able to see none...the throttle plate would have to GROW loool.

 

[tsi1991awd]

Ground out the ISC and set base idle via the BISS and see what happens.

 

[4gfun]

Well the Biss screw was not in at all. I previously mentioned that it was in all the way. I put the screw in all the way and idle fell all the way down.

I am still getting sticking when I get on the gas though. Perhaps the cable tension isn't right?

I took the throttle body apart again to try and get the slight stick out but couldn't. I wonder if this will go away on it's own.

 

[LiquidX]

Your plate is catching on the throttle body bore surface. Undo the 2 screws holding the plate down and recenter it. You can also turn the screw on the cable side to change how "closed" the plate goes.

You don't want the BISS all the way in either as the IAC won't have enough "play" to function properly.

Side note, what all did you lube up prior to re assembly?

 

[snowborder714]

Your plate is catching on the throttle body bore surface. Undo the 2 screws holding the plate down and recenter it. You can also turn the screw on the cable side to change how "closed" the plate goes.

It is either one of these two issues. You need to be able to fully open/close the throttle body with no cable tension on it to figure out if it's the plate.

Scott, the 1g throttle body doesn't have a screw, but instead has the idle position switch (that I mentioned in my first post). Here's how to adjust it properly.
http://www.dsmtuners.com/forums/151826306-post2.html


The TPS can be mounted either way and it wouldn't matter.

 

[LiquidX]

If he didn't take the cable bracket off of the IM then I don't see how exactly it would be the cable. If he did then perhaps.

Maybe the 1g turbo TB has no screw but the 1g N/T has the screw adjustment (cable stop?) on the back side which limits how closed the plate can close.

 

[steve]

If you cleaned the throttle plate you also might have removed the sealer on the back side the factory uses to eliminate the air leaking by the shaft in the bore. That can cause it to idle high and surge.

I did it to mine and had to replace the TB.

 

[LiquidX]

If you cleaned the throttle plate you also might have removed the sealer on the back side the factory uses to eliminate the air leaking by the shaft in the bore. That can cause it to idle high and surge.

I did it to mine and had to replace the TB.

Do you have a picture of this "sealer"? I haven't seen it on either of mine and haven't had any issues even after taking my Dremel to clean the plate.

 

[snowborder714]

Maybe the 1g turbo TB has no screw but the 1g N/T has the screw adjustment (cable stop?) on the back side which limits how closed the plate can close.

Both 1g's have the idle position switch. Don't believe me?


I've never heard of this sealer, Steve. Any more info? I'm guessing when I media blasted mine it got removed and I've never had an issue.

 

[LiquidX]

Ah I wish I had my car so I could take a picture for you...Grrr

Well I looked online for some pictures and surprisingly it seems MY TB is the odd ball. I don't have the switch anymore but there is a screw in it's place Not like I need that sensor anyway haha.

 

[steve]

Do you have a picture of this "sealer"? I haven't seen it on either of mine and haven't had any issues even after taking my Dremel to clean the plate.

I've never heard of this sealer, Steve. Any more info? I'm guessing when I media blasted mine it got removed and I've never had an issue.

Can't find any pictures online tonight. I'll have to take some tomorrow.

 

[tsi1991awd]

Ah I wish I had my car so I could take a picture for you...Grrr

Well I looked online for some pictures and surprisingly it seems MY TB is the odd ball. I don't have the switch anymore but there is a screw in it's place Not like I need that sensor anyway haha.

Yea, actually you do need that sensor man. It connects to a single green wire connector that goes to the ECU to tell it when the throttle body is closed. Without that, the ECU never knows when it is closed and it surges.

 

[snowborder714]

He has a 2g and uses either a 2g TPS (which incorporates that wire) or idle switch simulation using ECMlink. Any 2g with their stock TPS does not need to connect anything to that sensor.

 

[steve]

Without that, the ECU never knows when it is closed and it surges.

You already got schooled on the need for a 1G IPS when using a 2G TPS but you also got the function backward. The ECU will not check for decel fuel cut off if it doesn't see the throttle closing. No IPS, ECU doesn't know the throttle is closed, no surging. You also loose idle control, dashpot emulation, decel fuel cut, and a few others so disabling the IPS isn't a cure for fixing idle surge.

 

[LiquidX]

Where's that picture Steve?!

 

[steve]

Here's two examples. One from a 1G DSM Turbo throttle body and another from a 1G NA 3S. You can easily see the sealant.

 

[4gfun]

Your plate is catching on the throttle body bore surface. Undo the 2 screws holding the plate down and recenter it. You can also turn the screw on the cable side to change how "closed" the plate goes.

You don't want the BISS all the way in either as the IAC won't have enough "play" to function properly.

Side note, what all did you lube up prior to re assembly?

Well, I took it apart again in an attempt to re-center it but still had the same issue. I took a dremel wire brush to the outside diameter of the plate and the bore and brushed it a little bit.

I shouldn't have put it back on the car until I got it right.

It still sticks but only when first beginning to open it. Thanks for the warning on the BISS. The good thing is that it is set too low right now so hopefully I didn't mess up the sealant that Steve mentioned.

I lubed it up with some of that plumbing grease that was used in one of the O-Ring style FAQs.

Is there a procedure for centering the throttle plate? It is so hard to tell when you have it just right. One FAQ says even light around the edges, the other says no light at all.

IMHO, I think the part that is causing the sticking are the two nuts that hold the throttle shaft (for the TPS and for the throttle spring). When I tighten them too tightly, the throttle shaft won't move at all. I am not talking about REALLY tight either. If I back off just a tiny bit, this is not the case.

So it is coming down to either the throttle plate not being centered or the throttle shaft nuts being over tightened.
I'd like to try and get this right soon. It won't be long before the gaskets I bought get tired of the on and off.

Also, I never took the cable off of the IM, I just removed the cable from the TB...but I did adjust it when I thought the BISS was all the way in and my idle situation was hopeless.

The problem is definitely inside the TB.

Any ideas?

Thanks as usual

Has anyone noticed that my throttle body shaft is opposite to the picture that Steve shows? Could anyone verify that my throttle plate is sitting the right way? This looks completely opposite to my TB! Maybe it is just me as I look at it closer....maybe the vacuum line direction is throwing me off?

 

[steve]

Has anyone noticed that my throttle body shaft is opposite to the picture that Steve shows? Could anyone verify that my throttle plate is sitting the right way? This looks completely opposite to my TB! Maybe it is just me as I look at it closer....maybe the vacuum line direction is throwing me off?

My pictures are of the side that faces the manifold, the back side of the TB. Yours is of the front side that faces the elbow. The screw heads should face the elbow like your picture shows.

 

[4gfun]

My pictures are of the side that faces the manifold, the back side of the TB. Yours is of the front side that faces the elbow. The screw heads should face the elbow like your picture shows.

Thanks for clarifying.

The culprit seems to be the throttle shaft nuts being on too tightly.

All, still have the same questions about how to adjust the throttle plate correctly...

 

[tsi1991awd]

Here's two examples. One from a 1G DSM Turbo throttle body and another from a 1G NA 3S. You can easily see the sealant.

Wow, neither my current DSM nor my old one had that sealer. Strange.

 

[LiquidX]

I agree, I've never seen that stuff before and honestly don't see how it would help out. Where the plate enters into the shaft will be sealed just from the plate and the outside is supposed to let a small amount of air through.