Tb idle
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Tb idle My new holley throttle body is having some problems. My idle is running a little high. Holley said that i may need to adjust the voltage on the tps or notch the tps mounting holes. Anyone know how to do this or has ever done this. Not exactly sure where to start on this one. 
get a multimeter and probe the wires the wire that voltage stays at around 5 volts is the reference wire coming from the pcm the wire that changes voltage with opening and closin of the throttle blades is the signal wire going back to the pcm
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Your supposed to slot the mounting holes in the TPS sensor so that you can adjust its clocking untill your voltmeter shows OE voltage at closed throttle. It should be at or near 5 volts at WOT, I just forgot what the closed position voltage should be.
I do know that your supposed to dial in the closed position and then just check the WOT position to make sure its still acceptable.
A good way to find out the OE closed throttle voltage would be to put your TPS back on the stock TB (assuming the blades have never been adjusted), plug it in to the harness, and read the closed throttle output voltage.
Once you get the TPS voltage output squared away, you may still need to adjust the TB blades to get the cold & hot starts, and idle where you want it. Just remember that the PCM is forgiving for small TB blade adjustments but SHOULD still have the TPS re-calibrated to the correct closed voltage. When you get that far, its a trail and error process of dialing it in.
A scanner that can tell you IAC counts would help alot though. Your goal then would be to dial in the TB blade position and TPS position untill the TPS output is in check and the IAC counts are centered in there range.
One more thing, if your linkage isnt going all the way to the stop, you should check the travel with the TPS off the TB to make sure it is in fact the cause of it not closing all the way. You may find that it is the culprit, or that your blades are contacting the bores and not allowing the linkage to retract to the adjustable stop.
I do know that your supposed to dial in the closed position and then just check the WOT position to make sure its still acceptable.
A good way to find out the OE closed throttle voltage would be to put your TPS back on the stock TB (assuming the blades have never been adjusted), plug it in to the harness, and read the closed throttle output voltage.
Once you get the TPS voltage output squared away, you may still need to adjust the TB blades to get the cold & hot starts, and idle where you want it. Just remember that the PCM is forgiving for small TB blade adjustments but SHOULD still have the TPS re-calibrated to the correct closed voltage. When you get that far, its a trail and error process of dialing it in.
A scanner that can tell you IAC counts would help alot though. Your goal then would be to dial in the TB blade position and TPS position untill the TPS output is in check and the IAC counts are centered in there range.
One more thing, if your linkage isnt going all the way to the stop, you should check the travel with the TPS off the TB to make sure it is in fact the cause of it not closing all the way. You may find that it is the culprit, or that your blades are contacting the bores and not allowing the linkage to retract to the adjustable stop.
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From: Champaign, Illinois
This is the kind of answer i was hoping for. Thank you very much.
The linkage is okay, first thing I checked. Once again, thanks for the help, this will give me a good project for tomorrow.
The linkage is okay, first thing I checked. Once again, thanks for the help, this will give me a good project for tomorrow.
Thread Starter
TECH Enthusiast
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From: Champaign, Illinois
Update: After notching the mounting holes in the TPS, I changed it's location which did improve idle. BUT, I am still having this problem that when I put my foot on the gas, it doesn't the linkage part doesn't go back to the idle bump stop. It stops just before that and causes the idle to stay at about 1200-1400. I thought that the problem might be in the TPS itself. So, I ran the car with the TPS off to see if it was something in the throttle body itself, and it still stuck just above idle.
Also, I decided to run it without the cruise control to see if that was preventing it from going all the way back. It still didn't go all the way back! I know it isn't in the throttle cable because there is enough play in it, so that should be fine.
Any new ideas, somewhere in the tb, the shaft may not be clearanced enough and is rubbing up against something, maybe???
I don't know, I think I am going to call Holley on Monday to see what they say.
Also, I decided to run it without the cruise control to see if that was preventing it from going all the way back. It still didn't go all the way back! I know it isn't in the throttle cable because there is enough play in it, so that should be fine.
Any new ideas, somewhere in the tb, the shaft may not be clearanced enough and is rubbing up against something, maybe???
I don't know, I think I am going to call Holley on Monday to see what they say.
