TBI: TPS percentage at WOT

[Dr_Grip]

I got a (hopefully) simple question: What should the TPS read at WOT? In my car (http://www.gearhead-efi.com/Fuel-Injection/showthread.php?4419-TBI-conversion-on-a-Ford-400-need-help-getting-it-to-run), it seems to be exactly 60% at kickdown. Naively, I'd have expected 100%...

[1project2many]

Ohboy... three different questions imo. What is TPS when foot is to the floor? What TPS reading causes WOT bit to be set? What is TPS when kickdown occurs? Start with "Foot on floor" to ensure WOT really is WO.

[lionelhutz]

Might as well add which PCM and adx too? Some just calculate the %TPS.

[Dr_Grip]

WOT just referred to pedal-to-the-metal, (mechanical) kickdown engaged, not to a bit being set, sorry for any confusion :) How can I set when WOT is set?


Might as well add which PCM and adx too? Some just calculate the %TPS.The ECM is a 1227747 with an ADSU-based bin and the adx file from this post (http://www.gearhead-efi.com/Fuel-Injection/showthread.php?304-1227747-ECM-Information-42&p=2207&viewfull=1#post2207). I am at my work computer right now but I'll look the adx revision as well as TPS voltage at full throttle up when I get back home.

[Six_Shooter]

On the '7747 any TPS % is a fudged number at best. There is no actual TPS % value in the datastream, so it is based off the TPS voltage.

The problem is that the ECM does not have an auto zero TPS function at key on, like later and smarter ECMs do, which is where the displayed % in a datalog can be sometimes misleading.

That being said, if the displayed % is only 60% based on some of he ADXs I've used with the '7747, it sounds like you may need to adjust the TPS and/or find out why the throttle is not going fully open. This should equate to around 2.8 to 3V of the TPS, which is too low for WOT on the '7747. Most of the time I see above 4.5V at WOT.

Have someone push the throttle pedal down while you look down the throttle opening (engine off obviously) and make sure the throttole plates are actually opening all the way. Sometimes floor mats can get in the way, pedals can bend, or linkage can bend causing a less than WOT situation.

[lionelhutz]

The PE mode in the PCM is different than WOT. There is a table %TPS vs RPM for PE mode that adjusts when the PCM enters PE mode. 60% TPS often gets used as the threshold to enter PE mode.

You can try tweaking the limits in the adx to display 0% and 100% correctly, but they will drift. It's better to just look at the voltage to determine if you're getting a good TPS signal. You need to make sure the voltages are reasonable anyway before you tweak any calculation for %TPS.

[Dr_Grip]

Thank you all!


On the '7747 any TPS % is a fudged number at best. There is no actual TPS % value in the datastream, so it is based off the TPS voltage. The problem is that the ECM does not have an auto zero TPS function at key on, like later and smarter ECMs do, which is where the displayed % in a datalog can be sometimes misleading. That being said, if the displayed % is only 60% based on some of he ADXs I've used with the '7747, it sounds like you may need to adjust the TPS and/or find out why the throttle is not going fully open. This should equate to around 2.8 to 3V of the TPS, which is too low for WOT on the '7747. Most of the time I see above 4.5V at WOT. Have someone push the throttle pedal down while you look down the throttle opening (engine off obviously) and make sure the throttole plates are actually opening all the way. Sometimes floor mats can get in the way, pedals can bend, or linkage can bend causing a less than WOT situation.Visual inspection looks good. http://pic.armedcats.net/d/dr/dr_grip/2015/08/17/IMG_20150817_184451.jpg (http://www.armedcats.net/image/view/KElC2m9kviB50Xnd) And a dry run log shows that I misread or misremembered the value when posting earlier. The attached log looks OK to me, what do you think?