Voltage limitations of TPS and "PE" mode issues (FAST intake & TB)
09-01-2004, 09:14 AM
#1
Voltage limitations of TPS and "PE" mode issues (FAST intake & TB) We ran into an issue yesterday with excessive TPS voltage on a car with the FAST 90mm intake and TB. Car threw a code for high voltage. On the A/F graph, the car would be fat upon rolling onto the gas, but when we went WOT, the A/F would spike to 14.5:1 and stay there.
We figured out the excessive voltage with the TPS was causing the PCM to exit the PE tables or something similar. We had to "finagle" the TPS sensor so it would max at 4.7V, and then the issue was resolved.
I don't have a Volume 2 for my Helms manuals, but was curious what it says about the voltage limitations of the TPS sensor and what the effects are if the high threshold is exceeded?
We figured out the excessive voltage with the TPS was causing the PCM to exit the PE tables or something similar. We had to "finagle" the TPS sensor so it would max at 4.7V, and then the issue was resolved.
I don't have a Volume 2 for my Helms manuals, but was curious what it says about the voltage limitations of the TPS sensor and what the effects are if the high threshold is exceeded?
09-01-2004, 11:47 PM
#2
It's very similar to what happens when people grind too much off the stock throttle body's bump stop. 5.0V is the absolute limit, but since voltage is not constant 4.8ish is safe.
09-02-2004, 04:30 AM
#3
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this is the first time anyone has said that 4.8 is safe, is this on all model cars? i've seen my bro's 99 do 4.71 but i though the absolute limit was 4.7V.
i wonder if different years/models have different opening thresholds, otherwise im gonna go work it some more
i wonder if different years/models have different opening thresholds, otherwise im gonna go work it some more
09-02-2004, 08:32 PM
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Did you measure the blade position with a caliper?
Pull the TB and measure the distance on the motor side at WOT from both sides of the blade to the housing.
The cam can rotate on the shaft and vary your actual position vs sensor position.
Pull the TB and measure the distance on the motor side at WOT from both sides of the blade to the housing.
The cam can rotate on the shaft and vary your actual position vs sensor position.
09-03-2004, 02:27 AM
#6
There are just a lot of little variables that determine the max voltage. How hard the throttle is hit and voltage not being a completely stable reading are the main culprits.
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09-03-2004, 08:55 AM
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Believe the TPS has to stay above 4.7V for some
period to fault; the higher the TPS voltage skew,
the easier to do this.
But definitely want to set up the mechanical
stop for dead-horizontal blade (center of throat
by ruler) and then adjust the TPS for electrical
output to match (dead center = 4.6V).
http://community.webshots.com/photo/...56178307xTnvId
period to fault; the higher the TPS voltage skew,
the easier to do this.
But definitely want to set up the mechanical
stop for dead-horizontal blade (center of throat
by ruler) and then adjust the TPS for electrical
output to match (dead center = 4.6V).
http://community.webshots.com/photo/...56178307xTnvId
09-03-2004, 09:21 AM
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Originally Posted by Reckless
We ran into an issue yesterday with excessive TPS voltage on a car with the FAST 90mm intake and TB. Car threw a code for high voltage. On the A/F graph, the car would be fat upon rolling onto the gas, but when we went WOT, the A/F would spike to 14.5:1 and stay there.
We figured out the excessive voltage with the TPS was causing the PCM to exit the PE tables or something similar. We had to "finagle" the TPS sensor so it would max at 4.7V, and then the issue was resolved.
I don't have a Volume 2 for my Helms manuals, but was curious what it says about the voltage limitations of the TPS sensor and what the effects are if the high threshold is exceeded?
We figured out the excessive voltage with the TPS was causing the PCM to exit the PE tables or something similar. We had to "finagle" the TPS sensor so it would max at 4.7V, and then the issue was resolved.
I don't have a Volume 2 for my Helms manuals, but was curious what it says about the voltage limitations of the TPS sensor and what the effects are if the high threshold is exceeded?
