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

 

[4gfun]

Well update...since I have nothing to lose, I pulled out the dremel with the grinder bit and went gently around the edges.

Will let you know how it goes soon!

Thanks!

 

[steve]

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.

Clearly it does or the factory that makes the throttle bodies wouldn't go through the bother of applying it. It doesn't take much additional air at idle to change the idle speed. Think about how little you have to turn the BISS to make a change or how large a change in RPMs there is as you just crack the butterfly off it's stop.

Most of the untouched Mitsubishi throttle bodies I've come across have some amount of this used to seal them up. I don't remember anymore where I found the warning not to remove it when cleaning the plate but it was after the fact and a little too late. I imagine there are some TB that didn't need any sealer and it might be a large number when you consider production numbers but it's something you need to watch out for and not remove when cleaning the plate.

 

[4gfun]

Joy,

And I just ground down my throttle plate to make it fit...looking forward to the high idle! Hopefully I didn't take too much off and I can control the idle.

It doesn't seem too bad. There are still some places that I cannot see light.

Crossing my fingers!

Clearly it does or the factory that makes the throttle bodies wouldn't go through the bother of applying it. It doesn't take much additional air at idle to change the idle speed. Think about how little you have to turn the BISS to make a change or how large a change in RPMs there is as you just crack the butterfly off it's stop.

Most of the untouched Mitsubishi throttle bodies I've come across have some amount of this used to seal them up. I don't remember anymore where I found the warning not to remove it when cleaning the plate but it was after the fact and a little too late. I imagine there are some TB that didn't need any sealer and it might be a large number when you consider production numbers but it's something you need to watch out for and not remove when cleaning the plate.

 

[snowborder714]

Just so I'm clear on something, do you have an idle position switch on your throttle body? This will make or break a throttle body when dealing with sticking.

I've never had an issue with shaft nuts being too tight causing sticking. And I've never had to grind down a throttle plate to make it fit. You were doing something wrong, plain and simple.

 

[4gfun]

I have the idle position switch on the throttle body.

Well bad news, I ground the edges of the TB plate as carefully as I could. Now I can't get idle to go below 1400 rpm and I have constant idle surge. This is with the BISS screw fully in. I determined the final cause of the sticking too late.

There is a small white washer that goes underneath the metal "blade" that connects to the TPS.

With the washer in, it sticks consistently only after putting it together.

With it out, the sticking stops. I tested this over and over and over again.

I am guessing that I ground too much of the throttle plate edges off and now have high idle.

The good news is that it doesn't stick...the bad news is the idle surge.

Any thoughts on why it could be idling so high before I go through the saga of buying another throttle body?

The only thing that I can think of is the grinding that I did on the blades to make it fit.

Prior to this it idled at 800 rpm with the BISS screw all the way in.

TPS is at 9.7 % at idle per mmcd. It is not the throttle cable either. This happens with the throttle cable disconnected.

Thanks

Just so I'm clear on something, do you have an idle position switch on your throttle body? This will make or break a throttle body when dealing with sticking.

I've never had an issue with shaft nuts being too tight causing sticking. And I've never had to grind down a throttle plate to make it fit. You were doing something wrong, plain and simple.

 

[steve]

Sorry, you trashed it. You can try contacting throttlebodys.com and see if he has a extra stock sized throttle plate. I bet he has a few and start over again. Perhaps your new seals aren't seated all the way in.

 

[tsi1991awd]

Before you do anything, test your ISC out. Could be as simple as a bad ISC. It's a long shot but worth the few seconds it takes to test.

Also, it should have been painstakingly obvious that grinding the plate down was a bad idea. If it worked fine before, then it was installation error.

 

[4gfun]

Well remember, the idle was fine before grinding it down. So I guess that would rule the ISC out. Man, I am dumb but I guess that is how you learn. I can't believe that little white washer was the cause of my grief. Per the FAQ, not everyone TB has that washer....or as Steve said, maybe one of the seals isn't seated properly which is causing the washer to freak out.

Good idea on trying to get a stock throttle plate again. Might as well!

On a side note, I am not getting surge if I don't connect the throttle switch but the idle is still around 1400 rpm.

Is there any harm in running it like this? I don't care how it sounds...it isn't my DD anyways.

I am sure that it is not a good idea ...just the cheap side of me..most of us here have it

 

[snowborder714]

Every throttle body I've ever put together has had the white plastic washer on the shaft.

I'd say either get a new plate and start over, or send it to someone who has worked with them before.

 

[4gfun]

Every throttle body I've ever put together has had the white plastic washer on the shaft.

I'd say either get a new plate and start over, or send it to someone who has worked with them before.

The white washer goes on the TPS side above the seal but below the blade that moves the TPS right?

Just confirming. I wouldn't expect it to be missing that spacer on some TB either but that FAQ did say something about it. I put tons of grease on it too and it seemed to go smooth until I tighten the nut. I wonder if it is even required. Maybe it protects the seals.

I might try a new plate or as you say...cut my losses and get it out of here.

I am not much a quitter, but sometimes it is ok to lose.

 

[snowborder714]

You're correct on the washer.

Send me a PM if you need/want any help with it.

 

[4gfun]

Thank you

You're correct on the washer.

Send me a PM if you need/want any help with it.

 

[tsi1991awd]

When I rebuilt my 90 TB, the white washer was there. It is really really thin, I was wondering if it even helped at all. I put it back on anyways.

 

[4gfun]

When I rebuilt my 90 TB, the white washer was there. It is really really thin, I was wondering if it even helped at all. I put it back on anyways.

I wonder the same!

 

[tsi1991awd]

Yea, it was thin and flimsy. I could bend it

There was a metal washer under that as well, so I'm not sure what the plastic one's purpose is.

 

[4gfun]

Funny thing is, mine was not thin and flimsy at all. It couldn't be bent in any way...maybe snapped in half if I could get leverage or using a set of vice grips easily...but not flimsy at all. The thickness was about that of a nickel maybe. Mine had a metal lockwasher right below the nut, but no additional metal washer. hmmmmmm

Yea, it was thin and flimsy. I could bend it

There was a metal washer under that as well, so I'm not sure what the plastic one's purpose is.

 

[tsi1991awd]

Funny thing is, mine was not thin and flimsy at all. It couldn't be bent in any way...maybe snapped in half if I could get leverage or using a set of vice grips easily...but not flimsy at all. The thickness was about that of a nickel maybe. Mine had a metal lockwasher right below the nut, but no additional metal washer. hmmmmmm

Is that a 90 TB or a 91+? Mine was a 90, which also uses a different TPS

 

[4gfun]

It is a 91+ TB. The problem turned out to be the need to put that white washer around the shaft first not just kind of sit it there and let it get crushed.

Thanks for all of the help.

Is that a 90 TB or a 91+? Mine was a 90, which also uses a different TPS