Author Topic: TPS Setting, Battery Voltage & Throttle Blade Position?  (Read 229 times)

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Offline ~JM~

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TPS Setting, Battery Voltage & Throttle Blade Position?
« on: September 16 2021, 06:34:01 PM »
Recently installed a rebuilt Steve Monroe 62mm Throttle Body. Not the original TB, but I am using the original TPS. Battery has been in storage & is reading 11.9-12V. Battery Tender is bringing it back up to charge. Attempted to set TPS with Scanmaster. Numbers are very low. 30 is the best low setting so far.

How much, if any, does battery voltage affect setting the TPS?

While operating the throttle linkage by hand to full throttle, it appears that the throttle blade may not be quite a full 90 degrees open. May be an illusion, can't tell for sure. Appears that the lever contacting the throttle body casting would require relieving to open any further. Lever & linkage from original TB & swapped over to rebuilt TB.

Any advice would be appreciated.

Thank you.

Offline Steve Wood

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Re: TPS Setting, Battery Voltage & Throttle Blade Position?
« Reply #1 on: September 16 2021, 07:43:01 PM »
It's not a battery voltage problem.  The throttleblade is usually a few degrees away from being 90 degs so that sounds normal.

Something else is not right.  Is the iac screw emerging the usual approximate 1.5 threads or so out of the tb?
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Offline ~JM~

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Re: TPS Setting, Battery Voltage & Throttle Blade Position?
« Reply #2 on: September 16 2021, 08:28:17 PM »
It's not a battery voltage problem.  The throttleblade is usually a few degrees away from being 90 degs so that sounds normal.

Something else is not right.  Is the iac screw emerging the usual approximate 1.5 threads or so out of the tb?

Unknown at this time. IAC unit was swapped from original TB straight over to new TB (bottom side of TB).

The screw that would be considered an idle adj screw on a carb, shows about 2 threads extended.

I performed a voltage test on the TPS gray wire. Less than 2V. Supposed to be 5V I think.

Battery is about 12V now. Not up to 13+V.

This engine had the top-end removed down to the block. Heads, valves, springs, gaskets, ARP studs. New timing chain & oil pan gasket. New HR motor mounts. TA Perf D-side header. New TT 80# inj. w/new chip & Racetronics inj harness. Razor alky system installed w/3.5Bar stainless MAP. Caspers audible knock detector installed at ECU. 5V to MAP taken from gray wire at ECU & routed through firewall at speedo grommet to back of intake manifold. That wire reads the same as the gray wire at TPS. Green wire from MAP to Alky PAC reads .6XX (less than 1V)

Grounds at rear of passenger head cleaned & returned to original location. Same with battery ground to engine block.

Ground from MAP to firewall by master cylinder.

Redundant ground at battery to fender-well location.
« Last Edit: September 16 2021, 08:33:28 PM by ~JM~ »

Offline Steve Wood

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Re: TPS Setting, Battery Voltage & Throttle Blade Position?
« Reply #3 on: September 16 2021, 08:45:17 PM »
Sounds like you have a problem with the tps wiring then.  It has to read 5v to work right. Or there is a problem at the ecm

Check the voltages shown on the diagram at the ecm.  It could be the ecm assuming the voltages into it are right
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Offline ~JM~

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Re: TPS Setting, Battery Voltage & Throttle Blade Position?
« Reply #4 on: September 16 2021, 09:33:36 PM »
Interesting finding.

I unplugged the Metripack connection to MAP sensor & now have 5V at TPS. TPS has been set at .42 to 4.58/4.60.

Something is crossed up at MAP.
« Last Edit: September 16 2021, 11:15:37 PM by ~JM~ »

Offline daveismissing

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Re: TPS Setting, Battery Voltage & Throttle Blade Position?
« Reply #5 on: September 19 2021, 06:49:20 PM »
More than you wanted to know about MAPs: https://www.robietherobot.com/storm/mapsensor.htm
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Offline ~JM~

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Re: TPS Setting, Battery Voltage & Throttle Blade Position?
« Reply #6 on: September 19 2021, 07:34:53 PM »
More than you wanted to know about MAPs: https://www.robietherobot.com/storm/mapsensor.htm

That's some good info. Thanks.

I'm using a different MAP sensor. Discovered I had 2 wires swapped. Works fine when you do it correctly.