Throttle Position Voltage
Thread Starter
Instructor
Joined: Aug 2003
Posts: 235
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From: Soddy Daisy TN
Throttle Position Voltage
Hey guys,
If I raise my TPS voltage in the idle position say from .56 volts to the max which is .75 volts, according to my shop manual, will the ECM send me a little more fuel at WOT? Thanks, Troy
1985 L98, Stock ECM
If I raise my TPS voltage in the idle position say from .56 volts to the max which is .75 volts, according to my shop manual, will the ECM send me a little more fuel at WOT? Thanks, Troy
1985 L98, Stock ECM
Le Mans Master
Joined: Feb 2000
Posts: 9,715
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From: Kempner Texas
Originally Posted by drumboytroy
Hey guys,
If I raise my TPS voltage in the idle position say from .56 volts to the max which is .75 volts, according to my shop manual, will the ECM send me a little more fuel at WOT? Thanks, Troy
1985 L98, Stock ECM
If I raise my TPS voltage in the idle position say from .56 volts to the max which is .75 volts, according to my shop manual, will the ECM send me a little more fuel at WOT? Thanks, Troy
1985 L98, Stock ECM
I've gone as high as .67 without a code. Raising the voltage effects the air/fuel mixture during part throttle operation, so raising the voltage will richen the mixture.
It works on the same principle as the accelerator pump on a carb.
Jake
Race Director
Joined: Oct 2000
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From: Enter Post Count Here
The ECM assumes you are WOT anything over 80% if I remember correctly, so you're not going to see any WOT improvement with 0.20 volts(4%).
Last edited by NoWorries; Sep 11, 2004 at 01:44 PM.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
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From: Kempner Texas
Originally Posted by Upstate
No. The ECM will just see WOT that much sooner and start adding fuel accordingly.
In my case, the - off idle - the exhaust is slightly deeper, engine feels smoother, and SOP part throttle acceleration feels stronger.
Of course these are subjective; I've never done back-to-back testing at the strip or on the dyno to see the actual effect the change has on real-world performance.
Jake
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
Bumping TPS voltage will not change WOT fuel or spark but will give a crisper throttle response.
The usual way to bump TPS base voltage is to increase it to .65Vdc at base idle of 450rpm. You could try bumping it to .75-.76Vdc at normal idle of 60-700rpm. If you get a code doing it that way just back off a hair.
If you want to add fuel at WOT, install an AFPR at the stock fuel pressure and then bump pressure for best performance.
Thread Starter
Instructor
Joined: Aug 2003
Posts: 235
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From: Soddy Daisy TN
Thanks man. I think that will be my next project. I also went to your site and looked at the procedure to reset base idle. CFI-EFI said that the ECM controlled that and burning a new chip was the only way to change it. I'm confused now. Can you help me? What RPM is base idle? What RPM is regular idle? Thanks, Troy
1985 L98
1985 L98
Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
CFI said that the idle speed is controlled by the ECM. He did NOT say the BASE idle was controlled by the ECM. Changing the BASE idle (called the minimum air adjustment) will NOT change the normal (curb) idle speed, because the normal (curb) idle is controlled by the ECM. If you have a Helms manual, you need to spend some time with it. If not, go to: www,helminc.com
RACE ON!!!
RACE ON!!!
Last edited by CFI-EFI; Sep 13, 2004 at 09:34 PM.
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From: San Diego, Ca
CFI is correct - There is nothing you can do to change the base idle. Crisp throttle response is dependent on having the minimum idle set correctly and the TPS at .54 +/- .06. Go above this number and the ECM will think the car is accelerating and it won't idle. Go below, and it will usually stall.