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350 Wont Idle/Will Idle Too High/ Wont Idle You get The Idea- SOLVED:)

You say it smokes. If there is smoke coming out around the IAC, then it might not be sealed like it should be.

Yeah, I remember you saying you had replaced it now.

I would check how it seals when you get the chance. If air is getting around it, that might be a problem.

I am beginning to suspect that you have something really basic wrong. Like a crack in the throttle body housing or something.

For instance, you replaced the IAC, but what if the seat in the body has cracked inside and the plunger cannot seal anymore?

Or the plunger in the injector is worn and allowing too much gas out.

I have a friend's intake in my shed, and I am going out there tonight when I get home to study that system.

I'm glad you are not home in Atlanta.
This thing is keeping me awake nights, and if you were home, I would be tempted to make a run up there from PC, and I don't have the funds to do that right now.

Hang in there, we'll beat this thing yet.
 
I have both TBI's with me and it did the same thing with either. I will pull the IAC and change the gasket as well as inspect the TBI for cracks near the IAC.

Fordum said:
You say it smokes. If there is smoke coming out around the IAC, then it might not be sealed like it should be.

Yeah, I remember you saying you had replaced it now.

I would check how it seals when you get the chance. If air is getting around it, that might be a problem.

I am beginning to suspect that you have something really basic wrong. Like a crack in the throttle body housing or something.

For instance, you replaced the IAC, but what if the seat in the body has cracked inside and the plunger cannot seal anymore?

Or the plunger in the injector is worn and allowing too much gas out.

I have a friend's intake in my shed, and I am going out there tonight when I get home to study that system.

I'm glad you are not home in Atlanta.
This thing is keeping me awake nights, and if you were home, I would be tempted to make a run up there from PC, and I don't have the funds to do that right now.

Hang in there, we'll beat this thing yet.
Click to expand...
 
Fordum
I believe I've got it now. I replaced the IAC and was sitting on the radiator inspecting the TBI while it ran. I could hear a vacuum leak so I felt aroud the TBI but got nothing. Then I got as close to the EGR valve as I could and I'm sure it's the problem. I'd dont get any vacuum when I pull the EGR hose off because it appears to be leaking out the diaphram.
 
The symptoms you described happened on my 87 K5.....I replaced every sensor, fuel pump, etc......I waited till the last piece to replace that fixed the problem >>>>>> EGR valve<<<<<<. That damn thing is expensive and I ended up spending more replacing stuff.

I now have spare sensors stored in the boxes the new ones came in. :doah:

I was gonna chime in earlier to suggest to replace your EGR but you figured it out first. Good job. :thumb:

http://coloradok5.com/forums/showthread.php?t=209270&highlight=EGR+valve

And I have since replaced the motor.....1 head was cracked.

Willie
 
That could be it. Vacuum to that is controlled by the computer, so it would be an intermittent leak.
You should be able to plug the vacuum line and even out the idle.

Just be warned that doing that might cause some pinging at various times when driving, and may set a code.

On my truck, there is a potentiometer on top of the EGR valve actuator that reports back to the computer when the valve moves and how far it moves.
If the computer commands a move and it does not see a reaction, it sets a code.

But, just to check and see if that is the problem while idling, it should be OK.

If that fixes it, then we need to see about getting you the right gears...
 
I hope that replacing this solves the issue. So you're saying that the ECM controlls the when exhaust gas is pulled into the TB by using the EGR vacuum selenoid? I would assume that exhaust gas is always present in the EGR valve and is only let into the TB when the selenoid recieves a signal. That would mean that there is a valve with in the selenoid itself.

Fordum said:
That could be it. Vacuum to that is controlled by the computer, so it would be an intermittent leak.
You should be able to plug the vacuum line and even out the idle.

Just be warned that doing that might cause some pinging at various times when driving, and may set a code.

On my truck, there is a potentiometer on top of the EGR valve actuator that reports back to the computer when the valve moves and how far it moves.
If the computer commands a move and it does not see a reaction, it sets a code.

But, just to check and see if that is the problem while idling, it should be OK.

If that fixes it, then we need to see about getting you the right gears...
Click to expand...
 
Well I sure hope this fixes the issue. It's $108.00 for the the EGR valve OEM #17087194. So yep, that is pricy.

wheels87k5 said:
The symptoms you described happened on my 87 K5.....I replaced every sensor, fuel pump, etc......I waited till the last piece to replace that fixed the problem >>>>>> EGR valve<<<<<<. That damn thing is expensive and I ended up spending more replacing stuff.

I now have spare sensors stored in the boxes the new ones came in. :doah:

I was gonna chime in earlier to suggest to replace your EGR but you figured it out first. Good job. :thumb:

http://coloradok5.com/forums/showthread.php?t=209270&highlight=EGR+valve

And I have since replaced the motor.....1 head was cracked.

Willie
Click to expand...
 
That is the way it works on mine. Yours too I think.

The old carb engines used a temperature valve to only allow vacuum to the EGR after the engine was warmed up, and then used other ports to control when it was allowed after that.

There is exhaust gas at the EGR all the time, but it only opens to let it into the intake when there is vacuum at the diaphragm.

And the EGR vacuum solenoid opens and closes under computer control to regulate the vacuum to the EGR.

On my truck, there is actually a regulated vacuum leak at the EGR valve. Its small, and I don't think you would hear it. But it has a small filtered hole open to the atmosphere that lets air in all the time.
That is done that way so the diaphragm can close the EGR valve faster when vacuum is removed from it.

When the solenoid is opened, the vacuum applied to the diaphragm is way more than the small leak can overcome, so the diaphragm pulls the EGR open.
When the solenoid closes, the vacuum goes away fast, and the EGR closes quickly.
 
Well problem solved. I bought the EGR for $108.00 but then found one in my junk pile. So I returned the new one and went with the old one. Now she runs like a top. I also replaced my heater core so she's set for now.

Now to re-gear. I've found a shop that will do it for $1000.00 but I'm still hesitant as I'm worried about how this will change performance and fuel consumption.
 
Fan-damn-tastic!

That damn truck was haunting me.

Now, as to the gears. You need to ask around here. I don't do lots of gear changes.
I generally know what I need when first start out, so I either buy the truck with the gears I want, or do it one time.

There are probably folks here who do it on weekends for fun.......

$1000 for both axles when you supply the gears, sounds high to me, but I am not the one to say.

If I were setup to do them, I would do a Ford 9 inch for a lot less, because its done on the bench.
But, the ones done on the truck are more of a pain.

As for performance and gas mileage, I suppose there is some way to accurately predict what will happen, but most of the time its a tossup.

Actually, thats not true when it comes to performance.

Unless you want a real high top end speed, you will like the performance.
Depending on which gear set you put in, it will feel like you have added 200-400 horsepower.
It will accelerate faster, be quicker in general, and tow effortlessly.

Gas mileage, however, is another matter.
It is possible for an increase, especially if you were running an automatic, but most time you lose some mileage in driving around.
You might gain some when you are towing though.

What will happen, is that the "sweet spot", the speed that it gets best mileage will change.

From what I can tell though, it does not sound like you do a lot of driving at that speed anyway.

The trick is, which gears?

Since you do not want to do it twice, it would behoove you to get it right the first time.

For maximum effect, if you are doing a lot of towing, and its fairly heavy, I recommend the taller gears. 4.89, or whatever they were.

Its Monday, and things are fuzzy.
The 4.11, or 4.10, again, whichever, is a good compromise, and you will notice the effect, but will not help as much as you might need with a big trailer.

Especially if you go up mountains.

Ask around for price estimates, 4X4HIGH seems to have a good feel for these things.
Plus you might start a new thread asking for advice.
 
So the problem all along was a bad EGR valve?
 
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