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89 K5 Blazer Running Rich and Idling High

eagle mark said:
There's only one more thing I can think of! Is your throttle returning all the way to the stop screw? The Minimum air screw you set back to exactly where it was before you removed the plug. Get up over the engine and look in there and you can see the metal linkage hit the other end of the screw I'm pretty sure. Once I saw one bent to raise idle to compenstae for another problem.
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It does come back to the screw with the TBI blades closed. Me adjusting the screw was pointless as the blades were already in the fully closed position before I backed off the screw. Could it be that the throttle body needs changing? Or why is the ECM richening the fuel/air mixture.
 
GalDemSuga said:
It does come back to the screw with the TBI blades closed. Me adjusting the screw was pointless as the blades were already in the fully closed position before I backed off the screw. Could it be that the throttle body needs changing? Or why is the ECM richening the fuel/air mixture.
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Since the plug was still in, it was pointless to remove it and try anything. All this does is set minimum air through the throttle blades so they are not sucked shut at idle. The IAC controls idle. If I could think of anything else I would have.

Did you check for vacuum leaks as I suggested above? Just changing a gasket does not insure a vacuum leak is fixed. It could be somewhere else. PCV valve stuck open? PCV hose cracked? Vacuum brake booster hose or valve cracked. Your high idle and no codes really points to a vacuum leak.
 
eagle mark said:
Since the plug was still in, it was pointless to remove it and try anything. All this does is set minimum air through the throttle blades so they are not sucked shut at idle. The IAC controls idle. If I could think of anything else I would have.

Did you check for vacuum leaks as I suggested above? Just changing a gasket does not insure a vacuum leak is fixed. It could be somewhere else. PCV valve stuck open? PCV hose cracked? Vacuum brake booster hose or valve cracked. Your high idle and no codes really points to a vacuum leak.
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I checked for vacuum leaks and did not find any beyond the TBI gasket. To ensure that there were no more leaks, I replaced all of the vacuum hoses to the TBI. I replaced the IAC, PCV, Crackcase Breather, EGR Vacuum Solenoid and EGR Gasket. There are no leaks at all. I then drove 60 miles and then rechecked for engine codes. Again the only code I got was code 12.

I am stumped. I just ordered a ALDL cable so that I may log data from the computer while I drive the truck. It should arrive shortly and I hope this points to the problem after reviewing the data.
 
Disconnect your brake booster and plug the vacuum line at the manifold. The booster diaphragm may be leaking. Many people overlook this.
 
eagle mark said:
Mine don't... plug the line to the brake booster, see what happens?
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No change after plugging the line. however, I replaced the TPS and there is definitely a change in Idle. Its lower now but I'm unsure at what RPM level it should operate nor do I have a gauge to check it. I will be able to see this once my ALDL cable arrives and I run WINALDL.

For now it's addressing the next problem(s): oil leak and a weird shifting tranny.
 
BGKYK5 said:
My '91 with a 700R4 idles at 650 RPM more or less when warm.
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I'll keep this in mind when I get that cable.

My tranny rough shifts from 1 to 2(2 to 1) and then shifts softly from 2 to 3 and 3 to 4. It goes into OD at about 50. All this at pretty low RPMS. I say that based on the sound of the motor. Just doesnt have that pedal response when going from 2 to 3 and 3 to 4.
 
Make sure the TV cable is set properly, not being set properly as said before will kill a trans quick, It will also shift differently. Just noticed you're from Atlanta, what part?
 
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WJACKSON11X said:
Make sure the TV cable is set properly, not being set properly as said before will kill a trans quick, It will also shift differently. Just noticed you're from Atlanta, what part?
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I'm in Fairburn. I'm getting much better perfromance from tranny. I erplaced the governor and readjusted the TV cable. While she still shifts rough in between 1-2 and 2-1, she upshifts abd downshifts great now at WOT.

I've got the Idle down and am now focusing on replacing the rear main seal which I'll have done this coming Tuesday.
 
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