1g TB swap, need help diagnosing problem

[always_broken]

Just finished porting my Intake manifold and 2g tb elbow to match my 1g tb. Hooked everything up started her up and the car freaked out.

It reved up to red line as soon as I started it up so I immediatley turned it off. I d/c throttle cable and same thing happened.

I aksed my chic to see if the tb lever or tps was moving and it wasn't. So I d/c the tps and it made a return to normal position snap noise. Put the tps back on and it stayed steady, throttle cable still d/c.

Now I put my throttle cable on and tried it again, it revs to 3 grand and goes to 1 grand. Then it fluctuates to 1-1.5. Repeatedly....

I hear a vacuum leak so before I attack that does that sound like a problem? I didn't modify the vacuum lines and t it because I'm not sure about the egr thing. Now my gas pedal feels like I gotta put a little more umph into it to rev it up. Like it's slacking. So on that note how tight should the throttle cable be?

 

[romeen]

It does sound like a vacuum leak to me. My PCV valve vacuum hose tore once and the car did the same thing. RPM's way up when first starting and then kept surging drastically just like you are describing. Keep looking for that leak, I'm confident that it's there.

For the throttle cable you want to be able to pull on it just a bit before it starts to rotate the throttle linkage.

 

[always_broken]

Ya, we put soapy water on the tb elbow to tb gasket area. Started bubbling... so I'm gonna get some RTV and hopefully it will help seal it up.

As for the cable, besides the mounting bolts behind the fuel rail, how else do you adjust it? No matter how far up or down I move the nuts where the acc. box it doesn't stay tight.

 

[romeen]

1) I wouldn't be surprised if there is another vacuum leak in addition to the one you found. The symtpoms you described make it sound like a pretty good size leak.

2) For the throttle cable you are adjusting it by sliding the bracket that is attached to the back of the intake manifold by two 10mm bolts, correct? There is also a screw on the back, lower side of the TB (at least that is where it is on the 2G). It has a fine thread pitch and is held in position by a nut. If you look closely the tip of it should be touching the TB linkage for the cable (I forget the proper name of the piece) when the TB plate it closed. I believe that is for fine tuning the tension of the cable. Truthfully, I have never needed to mess with it so I am not 100% positive but looking at it I don't see what other purpose is may serve. If you look at it it will be self explanatory. Don't forget to tighten the retaining nut back down after any adjustments.

If I am wrong about the purpose of this screw hopefully someone will chime in. Just in case you might want to use some white out or a marker to mark the position of it before adjusting just in case you need to return it to it's original position.

 

[JohnCIV_Talon]

I have a leak on my just now and that rtv wont work from the outside. I tried, your gonna need to take it all off and put some around the outside of the gasket.

 

[JohnCIV_Talon]

Its called the biss screw. Thats another way to adjust the idle. Search Biss Screw on here and you will find it easy. Tighten it to lower the idle.

 

[romeen]

I have a leak on my just now and that rtv wont work from the outside. I tried, your gonna need to take it all off and put some around the outside of the gasket.

Now you know that RTV always needs to be applied between whatever two surfaces you will be pressing together. Since you don't want any excess squeezing out towards the inside of the TB use a very thin layer and let it set up for 10-15 minutes before pressing things together.

I'm not sure if the comment regarding the BISS screw was for me or not. The screw I was referring to is on the back (firewall) side of the TB where the linkage that controls the opening of the TB plate is. The semi-circular pulley type thing that the throttle cable hooks onto (I still can't remember the name of it.......damn dementia) actually rests against the tip of the screw when the throttle plate is closed. You can use the screw to adjust the tension/free play of the throttle cable. I'm describing this for you only because of yesterdays thread and I know you are doing the same project.

Speaking of BISS screw don't forget to spray soapy water on that too when you do a leak test because they are known to leak due to the o-ring getting old and worn.

 

[always_broken]

Oh, really? If I adjust that little nut it will adjust tension on the tb cable? Biss screw isn't leaking btw, it's all on the tb elbow..I'll keep this thread updated.

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[JohnCIV_Talon]

You dont want to loosen that to much becasue it will fall off and everything could un ravel. Im not sure if that will even loosen the cable though..

As for my problem I just took off and put my tb on in half the time and while it was off I put some gasket sealant on the edges of both sides of both gaskets. Ill keep you up dated. Needs to dry.

 

[romeen]

Oh, really? If I adjust that little nut it will adjust tension on the tb cable? Biss screw isn't leaking btw, it's all on the tb elbow..I'll keep this thread updated.

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NO, don't loosen that one.. It's the screw in the lower right portion of the picture. You can see the head of it right in front of your finger. If you look at how it is positioned it will be self-explanatory on how it will affect the position of the throttle lever. Since I have never actually messed with mine I was hoping someone who has could back me up on it. But I can't imagine what other purpose it would serve. Like I said, mark it's position (it looks like it may already have white scribing paint on the threads) relative to the bracket that it is mounted in just in case you need to return it to it's original position.

Let me know if it works out.

 

[always_broken]

I see what you're saying...

Before I attack that I'm gonna fix the leaks, I just put soapy water in a spray bottle for more accuracy and I got results.


A tad bit of foam, I stress on the tad bit part, coming from the tb elbow to tb gasket.

And soapy water is being sucked in from the intake to tb gasket area.

Im going to get some silicone and see if this helps. I'll keep this thread updated.

 

[always_broken]

Alright, well the gaskets I bought from the auto store and they sucked.

I love their service but the product they sell was cheap cardboard. I ended up porting my stock 52mm gaskets to 60mm. I used rtv on edges and outside tb lines when sealed up and the boost leak is gone!! Whoo!

Well now I got the same problem again with the reving! I started it up and I idled it out. So far so good, then I tried to step on the gas pedal but it was stiff and would not move! So I turned it off and saw that the throttle cable was frayed a tad bit over by the box connected to the firewall. Clipped it off and pulled in and out for any restriction, none.

Started her up and she reved up to red line again! IDK what's going on. the throttle cable isn't being pulled nor is the tb plate stuck open, so what could it be?

 

[romeen]

Before you attached the TB elbow did you attach the throttle cable and look to confirm that the throttle plate was fully closed at rest and fully open with gas pedal to the floor?

When you did the boost leak test about how long did the intake hold pressure?

Did you double check to make sure all sensors were hooked back up?

If you haven't already done it try resetting the ECU. I don't know if this will make any difference but it's easy to do and may be worth a try.

Also make sure your BISS screw isn't missing.

 

[always_broken]

Well, I'm thinking I didn't adjust the TPS right. Becuase I started it up again after double checking over everything, and it did it again. I moved my tps around and it went to 4 grand then quited down. But my gas pedal wouldn't move. I turned it off and gas pedal was in function again. Started it up again and high rev in action, . So it must be it, because there's no binding.

I did check the tb plate's function, all the way open when wot and sealed when not.


When I check the tps, I really just guessed on it. I didn't get the "check for continuity and no continuity."

 

[always_broken]

K, adjusted tps and idles normal. And the gas pedal not moving, that was a false statemnent. I just didn't press hard enough. Well I rev up and it idles back but it's inconsistent. I took it for a cruise and it seemed the t. cable got stuck and started to rev up to 2500-3000. that's it though.


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You see how the cable connects to the arm of the gas pedal? well I observed and some slack comes out of it. Should it be flush with the hole and not move or is this normal?

 

[jrpmp69]

What year dsm did the throttle body come from? Did you connect all the vacuum hoses back correctly?

 

[always_broken]

It came off a 93 talon, I did not t the lines to reuse my egr though. If you're familiar with that, so you think that would be the problem? I'm going to see as we speak.

 

[always_broken]

Bingo!

I thought I could get by not t'n my vacuum lines off, I speak from experience you MUST if you plan on re-using your EGR. My acceleration is nice and smooth, actually, a lot quicker now with this swap! I love it, thanks for the guidance everyone. I mean it.

 

[endeffect0]

I had a problem with that swap till set up the hoses for the EGR that stopped the weird idle bounce that I had happening. I just put a block off plate between the egr and the manifold for most the year then open it back up for inspections and such. Works fine for me.

You mentioned earlier that your throttle cable started to fray, that can cause it to get hung up inside the sleeve and add resistance, it could hang up and cause you to rev or idle high even when your not touching the petal. It may not be the problem, but either way its gonna need to be replaced some time might as well rule it out now.
Good luck