LT1 TPS Idle voltage?
Thread Starter
Le Mans Master
Joined: Feb 2002
Posts: 7,858
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LT1 TPS Idle voltage?
What is the acceptable range?
Back when I got a new TPS I got one of the adjustible type, same as OEM except slotted holes for the torx bolts. Now that I have Datamaster, I can see the TPS voltage my PCM see's. Shows 0.61 volts for idle, and that is not right, I'm thinking I need to set it somewhere between 0.41 and 0.55 volts.
In case anyone wonders what LT1 PCM needs to see in TPS voltage for 100% TPS, mine reads 100% at 3.84 volts and above.
Back when I got a new TPS I got one of the adjustible type, same as OEM except slotted holes for the torx bolts. Now that I have Datamaster, I can see the TPS voltage my PCM see's. Shows 0.61 volts for idle, and that is not right, I'm thinking I need to set it somewhere between 0.41 and 0.55 volts.
In case anyone wonders what LT1 PCM needs to see in TPS voltage for 100% TPS, mine reads 100% at 3.84 volts and above.
Thread Starter
Le Mans Master
Joined: Feb 2002
Posts: 7,858
Likes: 2
Re: LT1 TPS Idle voltage? (RichS)
Hmm... I was thinking 0.54v was going to be the expected stock spec. Was your reading from a voltmeter or was that what your PCM was seeing (shown w/ scanner like autoxray, datamaster, etc)?
My IAC goes into reset @ 0.63v on the TPS...
My IAC goes into reset @ 0.63v on the TPS...
My stock one before I started messing with anything was at .63. When I do any work to the car I make sure to set it at that.
Team Owner
Joined: Dec 2000
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From: SE NY
Cruise-In II Veteran
Re: LT1 TPS Idle voltage? (Lone Ranger)
Well it realy dosn't matter what is the setting so long as the voltage increases smoothly with throttle pressure. Beginning in '90 the ECM takes a reading at idle and establishes the idle value as well as the WOT value; that's why the stock unit was not adjustable.
Actually on my '88 the stock TPS setting at base idle (450rpm) is 0.54Vdc which goes to about 0.6x Vdc at normal idle (600-700rpm).
Actually on my '88 the stock TPS setting at base idle (450rpm) is 0.54Vdc which goes to about 0.6x Vdc at normal idle (600-700rpm).
Melting Slicks
Joined: Sep 2001
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From: Dover De
Advanced
Joined: Aug 2003
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From: Hudson OH
Re: LT1 TPS Idle voltage? (emsrescu)
With the DVM, what's the best way to pick up that signal? To me it seems that the harness must be plugged in and the ground and signal tapped into. That or run a clip lead from the 5v to the 5v input on the sensor and use the DVM on the other two?
Thread Starter
Le Mans Master
Joined: Feb 2002
Posts: 7,858
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Re: LT1 TPS Idle voltage? (65Z01)
I went ahead and set it to 0.53 volts for closed throttle (idle) setting. But regardless of idle voltage, the PCM triggers 100% TPS @ 3.84 volts. Idle can be set as low as 0.41v or as high as 0.63v and when 3.84v is reached the scanner shows the PCM start reading 100% throttle position (TPS POS).
I'm using Datamaster software running on a laptop PC to see this.
I'm using Datamaster software running on a laptop PC to see this.
