Throttle body blade adustment
Registered User
Joined: Sep 2004
Posts: 81
From: California
Re: Throttle body blade adustment
http://www.89tta.com/airrate.htm
check this web site out. Now of course if the TPS is not adjustable, then you can't adjust it. Blocking off idle air contol intake port in front of throttle plate will do the same thing without going through all the computer stuff.
check this web site out. Now of course if the TPS is not adjustable, then you can't adjust it. Blocking off idle air contol intake port in front of throttle plate will do the same thing without going through all the computer stuff.
Registered User
Joined: Dec 1969
Posts: 27,725
From: Little Rock, AR
Re: Throttle body blade adustment
Originally Posted by 1991l98g92
The computer controls the idle RPM not the throttle plate screw. Unless the computer has been disabled or removed, the throttle plate screw DOES NOT
control idle RPM. The IAC motor contols the idle depending on how much air is going around the throttle plate. With the idle air control motor fully closed, that's called "Minimum Air Rate." Look up the adjustment procedure for that. Once the Min Air Rate is adjusted the throttle plate is adjusted and the tamper plug is reinstalled so it won't be messed by some one who thinks that's how you adjust the idle RPM. I have had to do that on many a GM when they come to our shop and the car either dies coming to a stop, because the throttle plate is caked with carbon. Or some one has messed with the screw and didn't look to see it was dirty.
control idle RPM. The IAC motor contols the idle depending on how much air is going around the throttle plate. With the idle air control motor fully closed, that's called "Minimum Air Rate." Look up the adjustment procedure for that. Once the Min Air Rate is adjusted the throttle plate is adjusted and the tamper plug is reinstalled so it won't be messed by some one who thinks that's how you adjust the idle RPM. I have had to do that on many a GM when they come to our shop and the car either dies coming to a stop, because the throttle plate is caked with carbon. Or some one has messed with the screw and didn't look to see it was dirty.
Thread Starter
Registered User
Joined: Jul 2003
Posts: 88
Re: Throttle body blade adustment
The previous owner claimed that he had ported the TB. But based on what I see, he "polished." The fact is that by turning in my idle screw, my erratic idle went away, and my idle rpms went down to a steady 800 rpms, from 2500 rpms.
The statement tahe the TB blades don't need adjustment is a generally true statement, but you never know if a nother person has messed up the factory setting. In my case, the no tamper plug was even missing.
The statement tahe the TB blades don't need adjustment is a generally true statement, but you never know if a nother person has messed up the factory setting. In my case, the no tamper plug was even missing.
Registered User
Joined: Jan 2004
Posts: 1,406
From: Downey, CA
Re: Throttle body blade adustment
Originally Posted by Injuneer
800 rpm is factory setting at idle, coolant fully warmed up. I disagree with the above "throttle setting procedure". You want to adjust the throttle stop screw until you get the correct rpm, AND the IAC counts are in the range of 20-40. Then check the TPS voltage to insure it is within the factory spec of 0.20-0.90V.
You should see 5V constant across the black and grey wires. The signal, across the blue and black wires, should be in the range of 0.20-0.90V with the blades fully closed, approx 4V above the "closed" value at the WOT position, and the voltage should change smoothly as you slowly rotate the throttle blades from closed to full open.
Your confusing things by continuing to run with water in the fuel. Get the tank drained immediately, put in a tank of good gas, and then attack the TPP problem
You should see 5V constant across the black and grey wires. The signal, across the blue and black wires, should be in the range of 0.20-0.90V with the blades fully closed, approx 4V above the "closed" value at the WOT position, and the voltage should change smoothly as you slowly rotate the throttle blades from closed to full open.
Your confusing things by continuing to run with water in the fuel. Get the tank drained immediately, put in a tank of good gas, and then attack the TPP problem
and will be installing a new TPS while I'm at it. I could not have asked for
better info. Thanks Injuneer. And thanks Shoebox for the comment
that the PCM checks the TPS voltage at start up to establish 0% open.
Looks like this job is going to be a piece of cake. Although I don't have a
fancy scanner, the HPP w/ power scan does the job just fine. If I remember
correctly, 0.57V seems to be the sweet spot for the TPS closed.
Thread Starter
Registered User
Joined: Jul 2003
Posts: 88
Re: Throttle body blade adustment
I have to agree that there has been agreat deal of good information. I know that I didn't understand the ECM/sensor/TB dynamics enough to get it running again with the info.
Thanks again for everyone's input.
Thanks again for everyone's input.
Administrator
Joined: Nov 1998
Posts: 71,094
From: Hell was full so they sent me to NJ
Re: Throttle body blade adustment
Originally Posted by 1991l98g92
The computer controls the idle RPM not the throttle plate screw. Unless the computer has been disabled or removed, the throttle plate screw DOES NOT
control idle RPM. The IAC motor contols the idle depending on how much air is going around the throttle plate. With the idle air control motor fully closed, that's called "Minimum Air Rate." Look up the adjustment procedure for that. Once the Min Air Rate is adjusted the throttle plate is adjusted and the tamper plug is reinstalled so it won't be messed by some one who thinks that's how you adjust the idle RPM. I have had to do that on many a GM when they come to our shop and the car either dies coming to a stop, because the throttle plate is caked with carbon. Or some one has messed with the screw and didn't look to see it was dirty.
control idle RPM. The IAC motor contols the idle depending on how much air is going around the throttle plate. With the idle air control motor fully closed, that's called "Minimum Air Rate." Look up the adjustment procedure for that. Once the Min Air Rate is adjusted the throttle plate is adjusted and the tamper plug is reinstalled so it won't be messed by some one who thinks that's how you adjust the idle RPM. I have had to do that on many a GM when they come to our shop and the car either dies coming to a stop, because the throttle plate is caked with carbon. Or some one has messed with the screw and didn't look to see it was dirty.
Registered User
Joined: May 2000
Posts: 1,327
From: Under my Car as usual :)
Re: Throttle body blade adustment
I actually think the 93 comes with one. I have seen them on there, but I don't do many 93 throttle bodies, which is why I don't see them often 
-Shannon
-Shannon
Registered User
Joined: Aug 2002
Posts: 238
From: Orlando, FL, USA
Re: Throttle body blade adustment another 93
Thanks guys,
I have the ASM Monoblade and PCMFORLESS is trying to get the A/F and idle correct. I have a 93 also, but it is a 12-1 CR, 383 Stroker with a solid roller cam and a .630 lift. I am running 110 racing fuel.
They can hear the car running on the dyno in a shop 1/2 mile down the road, through the tree line and 4 lanes of traffic moving.
Anyway those are the details. I have checked TPS readings and all are within speck, I also have the IAC working. PCMFORLESS gets the car closer to idle each time we dyno I am going to screw out the idle screw to open the blade because I think the speed density 93 is a totally different animal and it should work.
Any advise???
Jim
I have the ASM Monoblade and PCMFORLESS is trying to get the A/F and idle correct. I have a 93 also, but it is a 12-1 CR, 383 Stroker with a solid roller cam and a .630 lift. I am running 110 racing fuel.
They can hear the car running on the dyno in a shop 1/2 mile down the road, through the tree line and 4 lanes of traffic moving.Anyway those are the details. I have checked TPS readings and all are within speck, I also have the IAC working. PCMFORLESS gets the car closer to idle each time we dyno I am going to screw out the idle screw to open the blade because I think the speed density 93 is a totally different animal and it should work.
Any advise???
Jim
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