Look what followed me home:

Chris-Nelson · Post by **Chris-Nelson** » Mon Jun 02, 2008 11:18 am

FormulaGT wrote: I suggest pulling the plenum and using the black, high temp rtv on the EGR port. The gasket didnt seal for me, resulting in a very high idle similar to yours. Put a thin layer on the plenum and the block off plate (assuming thats what is used) and sandwich the gasket between them.

There is no EGR port.

FP seems high, should be 35. Once you fix the leak, that may drop back down tho.

I thought the fuel pressure should be at 44? At least that's what I've read before

Edit to say - That aftermarket TB is the first place I would look. It may not even be properly installed, or something is fubar with it. Try blocking off the TB with a flat peice of cardboard, you want to see if the car will run with it blocked off.

The throttle body is welded on to the manifold. There is no possibility of it leaking as far as how it is installed. I'll try to cover it though to see what happens.

Thanks.

FormulaGT · Post by **FormulaGT** » Mon Jun 02, 2008 5:19 pm

You welded the egr port on the plenum then?

FP is 35 at idle, 45 WOT.

I know the TB is welded. The butterfly could be jamming, a leak in the iac, or any other number of things. See what happens when you block it off.

Shaun41178(2) · Post by **Shaun41178(2)** » Mon Jun 02, 2008 5:36 pm

exactly. if you plug the tb and the car still runs you have a vacuum leak.

Also the pvc port on the upper intake you need to block that off. Do not run it into your lower plenum. That is WRONG!!!!! Or is that port the IAC port?

If that is the iac port then its hooked up right. If it is not the iac port then plug it, and then plug your port at your lower intake manifold. The port at the lower is not the pvc port. thats your iac port for the original tb. Thats where the bypassed air from the iac on the stock tb would run to. If the dohc tb has a built in iac port to feed the upper intake, then you need to block off the opening at the lower.

Block off the tb with a peice of cardboard or hell even your hand should work. If the car still runs then you obviously have a leak and need to figure out where.

I guarantee you have a leak though.

I have my fuel pressure set at 42. 44 is fine even though its a bit high. 38 would probably be good.

AntiCooter · Post by **AntiCooter** » Mon Jun 02, 2008 5:45 pm

Chris-Nelson wrote: One last peice of clarification however. This is how I have my UIM and LIM connected as far as vacuum lines go:

Isn't that tube by the throttle body for the coolant to warm the IAC passage? If so, the other end of it is open and you are just sucking air through that coolant passage. Either put a cap on both of those fittings or take that intake off and put the stock one back on to see if it will idle with it.

Aaron · Post by **Aaron** » Mon Jun 02, 2008 8:20 pm

AntiCooter wrote: Isn't that tube by the throttle body for the coolant to warm the IAC passage? If so, the other end of it is open and you are just sucking air through that coolant passage. Either put a cap on both of those fittings or take that intake off and put the stock one back on to see if it will idle with it.

No it isn't, they are constant vacuum sources.

AntiCooter · Post by **AntiCooter** » Mon Jun 02, 2008 9:15 pm

Good to know- the 3.4 F-body T/B I played around with had a pressed in tube that looked about the same. Learn something new everyday

Chris-Nelson · Post by **Chris-Nelson** » Tue Jun 03, 2008 12:14 am

The car finally set off an error code:
35

Idle Speed Error
The ECM will set code 35 when the engine speed is 75 RPM above or below the correct idle with closed throttle. This condition must be met for at least 45 seconds before the code is set. If idle speed is too high, check for vacuum leaks. If idle speed varies up and down, your engine might be running too lean (high air/fuel ratio). Check for low fuel pressure or water in fuel. If idle speed is too low, your engine might be running too rich (low air/fuel ration). Check for high fuel pressure or leaking/sticking injectors. Also, check all connections to the IAC and replace the IAC if necessary.

FormulaGT · Post by **FormulaGT** » Tue Jun 03, 2008 12:33 am

Ok....so its telling you the idle is too high, didnt we already know that?

Have you found the leak yet or not?

Aaron · Post by **Aaron** » Tue Jun 03, 2008 1:02 am

FormulaGT wrote: Have you found the leak yet or not?

:salute:

Your TB is fine as far as sealing goes I'm sure. Are the two ports that we talked about earlier either blocked off, or leading to something other than atmosphere? They are constant vacuum ports, used for FPR, brake booster, EVAP, or PCV. They need to be sealed.

Your PCV/brake booster setup sounds fine.

Theoretically, connecting the large LIM port shown to the smaller ports on the DOHC TB shouldn't make a difference, as they both have constant vacuum. But why not just plug them both?

Try, while it's idling without an air filter and idling high, placing your finger inside of the DOHC TB. There is a port before the actual blade, on the back side of the TB. This is for the IAC blade bypass. Place your finger completely over this port, sealing and blocking it. If your idle drops down to a semi-normal level, you have a bad IAC valve. These are fairly common failures on the 3.4 DOHC, and when they do fail cause an idle of around 3000rpm, so figure a bit lower on the 2.gay if that's your problem.

You have a vacuum leaks somewhere. Nothing else can cause a high idle.

Chris-Nelson · Post by **Chris-Nelson** » Tue Jun 03, 2008 1:40 am

Aaron wrote:
Are the two ports that we talked about earlier either blocked off, or leading to something other than atmosphere? They are constant vacuum ports, used for FPR, brake booster, EVAP, or PCV. They need to be sealed.

Yes they are both currently blocked off completely.

Try, while it's idling without an air filter and idling high, placing your finger inside of the DOHC TB. There is a port before the actual blade, on the back side of the TB. This is for the IAC blade bypass. Place your finger completely over this port, sealing and blocking it. If your idle drops down to a semi-normal level, you have a bad IAC valve. These are fairly common failures on the 3.4 DOHC, and when they do fail cause an idle of around 3000rpm,

The IACv is brand new so I hope it was not bad from the factory. It cost me like $70! But I will attempt this tomorrow.

You have a vacuum leaks somewhere. Nothing else can cause a high idle.

Why is this so hard to find...

Also, here is the new testing/diagnosis video:
http://videos.streetfire.net/video/Fier ... 164379.htm

Please have a look and tell me what you think.

Thank you all for all of your help and suggestions.

FormulaGT · Post by **FormulaGT** » Tue Jun 03, 2008 1:58 am

That second video shows you whats wrong.

When you blocked off the TB like I told you, the car died.

That leads me to believe that there is something fubar with the TB, like the butterfly/throttle plate isnt closing all the way. Did you check that? You did say you made a new throttle cable bracket, maybe that is what is causing the problem/hang-up?

Edit to add - it really was a silly idea to weld the TB in the first place. Now what happens if it needs replacement? Make a whole new plenum?

Chris-Nelson · Post by **Chris-Nelson** » Tue Jun 03, 2008 10:49 am

I'm pretty sure that when the car died because the TB got blocked off, that was a good sign - it meant no serious vacuum leaks.

What could the custom throttle cable bracket possibly have to do with a high idle and red-hot manifolds?

The throttle cable, when attached to the TB cam on the side, has a couple mm of slack still so I know that it is not holding open the butterfly.

Also, the TPS reads 0.81 vdc at closed TB and the butterfly does close all of the way.

I was pretty surprised to see a welded-on throttle body when I got the piece, but two things became apparent after I began playing around with it:
1. Unless it gets cracked and destroyed some how, the metal casting of the TB itself will never need to be replaced.
2. All of the components on the TB that could possibly go bad and need replacing in the future are easily removable and replaceable.

Thanks for the input.

Aaron · Post by **Aaron** » Tue Jun 03, 2008 2:11 pm

FormulaGT wrote:That second video shows you whats wrong.

When you blocked off the TB like I told you, the car died.

That leads me to believe that there is something fubar with the TB, like the butterfly/throttle plate isnt closing all the way. Did you check that? You did say you made a new throttle cable bracket, maybe that is what is causing the problem/hang-up?

Edit to add - it really was a silly idea to weld the TB in the first place. Now what happens if it needs replacement? Make a whole new plenum?

If the car died when he blocked off the TB opening, then it is one of two things:
1) The IAC or the wiring to it is still bad, which I wouldn't doubt. Try what I said, see if that changes anything.
2) The butterfly isn't sealing all of the way. This I also wouldn't doubt. Because of the welding on it, the pieces may have lost their tolerance. The blade is steel, and the housing is aluminum, so both are going to react to the welding differently. If the IAC tests good, then this is the case and you'll need a new TB. I'd get a 96-97 3.4 DOHC one, they are 64mm and bolt on. I've got a spare if you're interested.

Chris-Nelson wrote:I'm pretty sure that when the car died because the TB got blocked off, that was a good sign - it meant no serious vacuum leaks.

What could the custom throttle cable bracket possibly have to do with a high idle and red-hot manifolds?

The throttle cable, when attached to the TB cam on the side, has a couple mm of slack still so I know that it is not holding open the butterfly.

Also, the TPS reads 0.81 vdc at closed TB and the butterfly does close all of the way.

I was pretty surprised to see a welded-on throttle body when I got the peice, but two things became apparent after I began playing around with it:
1. Unless it gets cracked and destroyed some how, the metal casting of the TB itself will never need to be replaced.
2. All of the components on the TB that could possibly go bad and need replacing in the future are easily removable and replaceable.

Thanks for the input.

Yes, that is a good sign, your problem is with the TB.

If the cable isn't allowing the blade to close all of the way, then that is your problem. But if there is slack, the blade should be closing all of the way, unless as I said it got heated out of tolerance and now binds.

I would not have welded the TB on. There's a reason GM changed that design in 96-97. I much prefer bolted on TBs.

FormulaGT · Post by **FormulaGT** » Tue Jun 03, 2008 3:36 pm

Chris-Nelson wrote:
Also, the TPS reads 0.81 vdc at closed TB and the butterfly does close all of the way.

Theres another sign of the throttle plate not closing all the way.

I really do think thats your problem. Just the very slightest amount will allow it to have a very high idle. Try forcing it shut even more, its really hard to see if its closed all the way while its on the car.

TPS should read .4 V at idle.

Aaron wrote:
as I said it got heated out of tolerance and now binds.

Wouldnt suprise me. Im almost willing to put money on thats the problem.

Shaun41178(2) · Post by **Shaun41178(2)** » Tue Jun 03, 2008 11:15 pm

you blocked off the tb and the car died right? Ok well try blocking off just the iac hole before the throttle plate and see if that kills the car. If not then your throttle blade is getting hung open.

Afterall if you block off the throttle body completely and the blade isn't shutting all the way, then the car will still stall out. But by just blocking the iac hole, then you will know if the blade is warped or getting hung open and if the car stays running then there is your problem.

Oh yea I have a 272 cam and I think you do too right? I have 18 inches of vacuum at about 900 rpm. when hot. Cold I think is around 20 ish or a bit higher as the rpm is higher.

Chris-Nelson · Post by **Chris-Nelson** » Wed Jun 04, 2008 8:55 am

Headed to the race track for the day and when I get home I am going to swap out my UIM and 24 'lb injectors for the OEM UIM and 17's and see how it runs then...

The Dark Side of Will · Wed Jun 04, 2008 8:58 am

Put your finger in the hole, bitch! :bootyshake:

:thumbleft:

Aaron · Post by **Aaron** » Wed Jun 04, 2008 10:35 am

Chris-Nelson wrote:Headed to the race track for the day and when I get home I am going to swap out my UIM and 24 'lb injectors for the OEM UIM and 17's and see how it runs then...

My God you're an idiot.

There are only 2 places it could be, we've narrowed it down, just check the TB and IAC already. You're like a Old Europe guy, randomly replacing parts when the SES light comes on.

FormulaGT · Post by **FormulaGT** » Wed Jun 04, 2008 2:52 pm

Wait, I just watched the second video again because Im bored, and I actually watched the whole thing this time...

Your friends are telling you that its high idle is because of valve lash!?!?!

:rotflmao:

That was too funny...

Do yourself a favor and never listen to your friends mechanical advice ever again :thumbleft:

THE PUNISHER · Post by **THE PUNISHER** » Wed Jun 04, 2008 3:08 pm

Aaron wrote:
Chris-Nelson wrote:Headed to the race track for the day and when I get home I am going to swap out my UIM and 24 'lb injectors for the OEM UIM and 17's and see how it runs then...
My God you're an idiot.

There are only 2 places it could be, we've narrowed it down, just check the TB and IAC already. You're like a Old Europe guy, randomly replacing parts when the SES light comes on.

Holy shit dood..

Lighten up!