I changed my fuel injectors due to too much gas in the oil. I've done it before, labeled everything, etc., but when I started it up it goes to like 3500 rpm like it should, then drops to 2000rpm and no lower. When I turn on the A/C it then drops a little but its way too high

1. Dont think theres an air leak
2. Checked throttle cable freeplay
3. Upper TB butterflies are open, lower one closed when not touching gas pedal. Press gas pedal all the way in the lower one opens
4. I tried pulling a vacuum on the TB upper buttery diaphram but it would not pull vacuum (would that cause it?)

I noticed the cam thing pushes the TPS rod in all the way. The cam wont release it. Do I adjust that?

Question, do I need to take the TB off and adjust the cam behind in the back?

90 Vert, MTX

 

stupid question, but did you try adjusting the idle screw on top of the tb???

 

Upper TB flaps should be fully closed when the throttle is at idle position, the idle on your engine is a 'bypass' system that doesn't use the throttle flaps. Check the throttle linkage very carefully (is the connecting link for the third throttle valve bent or binding, maybe?).

 

You've got a vac leak, unless you somehow jammed the fast idle cam linkage, warm her up at idle and watch the thermowax plunger thingy with a mirror. The roller should move off of the cam when she's warmed up...

 

I havent touched the idle screw on top the TB because idle was good before I took the TB/Manifold off. So I think its something I did wrong

I used a stetescope and listened around but didn't find anything? Not sure where the leak could be? I figured it was a leak too

I looked at the plunger on back and it sticks out about a 1/4" when cold (plunger is white, right? Not sure I'm looking at the right thing). I haven't checked it when hot. I checked before I read this. I'll go try it now

Thanks for the posts!

 

I did a stetescope again and nothing. Could not find an air leak. I guess there could be one under the manifold, but I changed all those hoses so I doubt
it.

The thermowax plunger thingy, if I'm looking at the right thing, did not change. ??

 

If the Idle drops when you pull up on the gas pedal its a linkage problem

 

Are the coolant hoses still on the throttle body, or are they blocked off?

There's a fairly good pic of the fast idle cam system & thermowax in the FSM (and maybe Haynes), it's a bugger to find among all the chaos back there, I know....

 

When I pull up on the gas pedal with my foot it doesnt drop below 2000rpm. Freakin thing I been messing with it all day and its freakin hot! Seems like it should be easy. I even tried reseting the computer. I was trying to avoid turning any idle screws, etc., because I didnt have a problem before I took it off

All the TB body hoses are connected in the back. I really cant tell what is what back there even with a mirror. Guess I gotta pull the TB and check everything to the FSM? Thanks for the posts, any other suggestions you can think of is much appreciated?

 

Mine has a similar problem except its at 1500rpm. I got it down to the appropriate 800rpm, it was an easy fix, still need to adjust it

Where the throttle cable attaches to the main lever in the TB, the part that you can twist and rev the engine, that could be your problem there. Try twisting it to the fully closed position, as in give it a little force twisting it counter clockwise. This should shut the throttle completley and your idle problem should goto 800 or so. That lever, needs adjusting, well at least on my car anyways, havent had time to really look at it but there must be some kind of screw that sets it right.

 

Yeah, it does appear isolated to the rotating portion. I've been playing with it but can't figure out what caused it to become off??? If I physically rotate it the idle does go down some but I dont know what rpm its at. Not sure why its off, I'm still looking at it. Kinda hard to see back there. If you fix yours please let me know. Thanks

 

Ok, i left the manual at work and couldn't really get to the back, so I put white-out on the screw near the TPS/cam. I rotated this screw 4 turns. Started car and it did lower the idle, but when I engaged the clutch/trans the idle fluctuates up-down. The fluctating idle has happened before months ago and it turned out to be a loose (-) cable ground from batt-trans housing. It and other grounds are tight now.

Now, I returned the screw the 4 turns to its original position and started it. High idle again and when I engaged the trans the idle stayed high not moving.

Why is this happening?

 

When you start messing with your mechanical idle adjustments like this, you've got to jumper the initial set connector (green plug, near the leading coil pack), or your BAC valve will try to counter everything you're adjusting. That's probably what's causing the fluctuations...

 

I never would of guessed that. Stupid question, but theres 2 green connectors, one that has a singal terminal slot, and one green connector that has 3 terminal slots. I'm assuming its the 3-terminal, but which terminals do you jump??? Does it matter??

Also, I made the adjust ment with the car off before. Do I still need the jumper wire?

 

Ahh, you've got one of those S5 thingys...

I think you have to short the single prong green one to ground...The three prong one is your ECU code checker, if it's like the S4's. Don't do anything until someone with an S5 backs me up on this (or tells me I'm full of it, lol)

 

Ok, thanks. Does it say in the manual somewhere? Mines at work but i dont remember anything like that?

 

Hey...That's a good idea....Use the manual....j/k

I don't know about the S5's, but the S4 FSM distinctly instructs to jumper the initial set coupler before adjusting the idle via the TB adjustment screw (which, by extension, includes any linkage that will physically move the throttle plates, as far as I'm concerned)

 

WAYNE88N/A, you are right about the ground. I saw it today in the manual and I sure would of overlooked that. You ground the single green connector just like you said.

Didn't have much time or luck today, but started it up and its lower at 1200rpm (down from 1500-200). As it warmed up it got higher somewhat. Checked the codes, no codes came up. Sure sounds like an air leak, but again stethescope I couldn't find a leak.

I pulled up on the accelerator and it dropped to about 750rpm. Kinda rough but stayed there. Hit the gas and it goes up and wants to stay up. Pull back the pedal and it drops again. I think my throttle cable may be sticking.

Toay's questions
How do you unstick the throttle cable? Freeplay seems ok near the 0.12inch like book says. At least its not sounding like an air leak now-oh, idle does fluctuate when tranny is engaged. What can that be other than a ground????

 

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