I wondered today if that was the case. My idle voltage reads too high at .63 volts, is there anything I can do about that?
TPS adjustment... what the heck?
Thread Starter
Drifting
Joined: Aug 2006
Posts: 1,326
Likes: 18
From: Los Angeles California
TPS adjustment... what the heck?
All the guides to adjusting the TPS sensor voltage simply say that you "rotate the sensor." I do not see any way of doing this. The sensor only bolts down one way. Does anyone who has done this have any clarification?
Thread Starter
Drifting
Joined: Aug 2006
Posts: 1,326
Likes: 18
From: Los Angeles California
Melting Slicks
Joined: Jun 2004
Posts: 3,032
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It sounds like the LT4 setup is completely different..... Can you look at a FSM for your year? Whats it say?
Racer
Joined: Feb 2006
Posts: 269
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From: Vancouver B.C.
It's a non adjustable TPS. Either: 1) the wiring between TPS and PCM is faulting........2) PCM circuit is faulting.....or 3) TPS itself is faulting.
I'm having a similar problem, except pulling a 'TPS high voltage' code (new tps that reads like my old one....which is actually LOW voltage .36V to 3.8V).....so I must assume it's either my connections (wires) OR it's my actual PCM.
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NOT all L98 are adjustable. My '90 does have a tiny bit of slop in the bolt mounts that you can adjust about 1 degree but even according to the factory service manual... not adjustable.
Thread Starter
Drifting
Joined: Aug 2006
Posts: 1,326
Likes: 18
From: Los Angeles California
So the next question is, does it matter if the idle voltage is exactly .54 on the non-adjustable TPS sensors, or is the computer capable of accomodating itself to any idle voltage, like say .63 volts?
Drifting
Joined: Aug 2004
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Le Mans Master
Joined: Feb 2000
Posts: 9,715
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From: Kempner Texas
I agree.
In fact, on the 388 LT1 engine I just built, I elongated the slots on my TPS and adjusted mine to .67 because that's what Bryan at PCMFORLESS recommended when he reprogrammed my PCM.
On earlier engines that have the adjusable TPS, there is a range within which the voltage is acceptable. .54 is only the mid-point. From memory, I believe the range is +/- .075
On my 86, which has an adjustable TPS, the engine responded better set on the "high" side; .61/.62
Jake
In fact, on the 388 LT1 engine I just built, I elongated the slots on my TPS and adjusted mine to .67 because that's what Bryan at PCMFORLESS recommended when he reprogrammed my PCM.
On earlier engines that have the adjusable TPS, there is a range within which the voltage is acceptable. .54 is only the mid-point. From memory, I believe the range is +/- .075
On my 86, which has an adjustable TPS, the engine responded better set on the "high" side; .61/.62
Jake
Melting Slicks
Joined: Jun 2004
Posts: 3,032
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Le Mans Master
Joined: Dec 2000
Posts: 7,839
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From: San Diego, Ca
Everything GM built from at least '95 through today uses a non-adjustable TPS and all that I've worked on have an installed, closed throttle spec of .62 volts. Some when, replacing, require a special procedure with a bi-directional scanner. Unless you've got a TPS code (and you shouldn't with that reading), there is nothing to worry about. What are you trying to resolve?
