PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

Tps voltage too high, can it be disabled?

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Old Mar 11, 2014 | 09:32 PM
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Default Tps voltage too high, can it be disabled?

New tb allows the blade to rotate a little past horizontal which in turn gives it a full 5 volts and freaks out the pcm.

Can this fault be disabled to prevent the car from having problems or does it have to be mechanically limited?
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Old Mar 12, 2014 | 10:33 AM
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Adding a little series resistor in the hot leg could do
what you want, but there is no benefit to going past
center. Maybe drill and tap the stop-tang for a screw,
ot just wrap the thing in enough aluminum tape to get
it where it belongs?
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Old Mar 12, 2014 | 10:45 AM
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Thanks you Jimmy.

I am going to try to adjust the cable (lokar) but if that doesn't work I think I will do the drill and tap method. I hadn't even thought of that :bonk:

I was going to try welding a nut or something onto it. The stop is the same one used for idle stop so wrapping it would mess up idle (also it needs about 1/4" to be back in spec at under 4.71v)
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Old Mar 12, 2014 | 05:49 PM
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Adding a resistor is a bad idea. Did you buy a cheap throttle body? Seems like the backstop is messed up that allows the cam to go too far back.
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Old Mar 12, 2014 | 05:52 PM
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I meant the cast tang on the body, that the throttle
shaft tang comes to rest against. I shaved that on my
TB porting job to get full opening, going the other way
won't bother the idle-rest position.
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Old Mar 12, 2014 | 05:54 PM
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A throttle blade can close too far also and stick. It really sounds like you need a better tb instead of throwing the kitchen sink at it.
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Old Mar 12, 2014 | 09:49 PM
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Originally Posted by thunderstruck507
New tb allows the blade to rotate a little past horizontal which in turn gives it a full 5 volts and freaks out the pcm.

Can this fault be disabled to prevent the car from having problems or does it have to be mechanically limited?
Yes, Hp Tuners has the TPS High fail field that is 4.9V stock. It can be raised as high as 32V!

Russ Kemp
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Old Mar 12, 2014 | 10:03 PM
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But that is not a good idea nor should you do it.
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Old Mar 12, 2014 | 10:17 PM
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Originally Posted by coSPEED2
But that is not a good idea nor should you do it.
Worked perfect for a couple of cars that were hitting the 4.9v threshold. Just set the fail to 5v, no issues after.

Russ Kemp
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Old Mar 12, 2014 | 10:19 PM
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The first question is why is it hitting that threshold? You should answer that first, not just override it. That is why.
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Old Mar 12, 2014 | 10:39 PM
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Originally Posted by coSPEED2
The first question is why is it hitting that threshold? You should answer that first, not just override it. That is why.
Sometimes because of the throttle stop filed or slight differences in an aftermarket TB opening angle. Of coarse if your seeing 6v at WOT, then there's a problem that needs to be fixed.

Russ Kemp
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Old Mar 12, 2014 | 10:48 PM
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If you buy a cheap TB that may be, but that is a bandaid. The throttle cam should be adjusted on the shaft better or maybe a better quality tb should be bought. Why do you think the range is limited to 5v max?
Fudging the numbers to make do is never the way to tune.
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Old Mar 13, 2014 | 09:30 AM
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I had one of the older Fast TBs that had some things done to it in attempts to correct idle problems and wanted to try a new unmolested TB to see how much of the problem was mechanical and how much was tuning.

Overall the tb is a very nice piece, just the fact it's a swapped car with a modified throttle pedal arm and aftermarket Lokar cable is allowing me to get slightly too much rotation. I haven't even retuned the idle yet and driveability is improved.

The block is bolted to the housing which means I cannot drill and tap so I will just run a tig weld bead on top of it to act as a mechanical stop then gently grind until I get my desired voltage.

I would still take this over the old Fast 90mm any day of the week and sorry but I'm not spending $350-450 on the same thing just because this one was designed without a mechanical stop. It's not an ebay knock off, it's a sponsors product and it's a damn fine one minus this little hurdle, but "hurdles" is the name of the swapped car game.
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Old Mar 13, 2014 | 02:20 PM
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Just curious, what is your WOT TPS voltage?

Russ Kemp
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Old Mar 13, 2014 | 02:31 PM
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It is reading 5 volts (just barely as it fluctuates between 4.9 and 5) at WOT. It is my understanding this needs to be kept under 4.71v to prevent the fault code.

It probably wouldn't have been an issue but when the swap was first done the stock TB would not get full throttle so I modified the factory chevelle pedal arm to get more swing.
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Old Mar 13, 2014 | 02:36 PM
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Originally Posted by thunderstruck507
It is reading 5 volts (just barely as it fluctuates between 4.9 and 5) at WOT. It is my understanding this needs to be kept under 4.71v to prevent the fault code.

It probably wouldn't have been an issue but when the swap was first done the stock TB would not get full throttle so I modified the factory chevelle pedal arm to get more swing.
Every car that has your issue, I just change the TPS high volt fail to 5v. No big deal. As I mentioned, the stock TPS high volt fail is 4.9v.

Russ Kemp
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Old Mar 13, 2014 | 02:47 PM
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More importantly, whats your 0% throttle voltage at?
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