TPS Problem

[JustCallMeOrlando]

Hey all,

Just curious if anyone could shed some light on a problem i'm having. I can't remember this happening with my Gen2 setup, if it did it was a minor problem compared to its other issues

I find sometimes when I get back on the throttle after being off it, there is this pause where it does nothing, then all of a sudden I get this jolt when it does come back, not the smoothest thing in the world. It doesn't matter if you give it more throttle, nothing happens. If you do, it tends to give you an even bigger jolt when it does come back. I dont tend to find it happens when i'm giving it shit, only when i'm puttering around, then again, 90% of my driving isn't like that.

It's happened with both my Gen3 ECU's so i'm pretty certain it's external to them.

I'm pretty sure I checked that the TPS steps off the IDL position as soon as you crack the throttle.

I've once got an error code to say that TPS was in IDL and ACC at the same time, but i've not seen it since.

Does this still sound like a TPS calibration problem, or a borked TPS?

Cheers,
Nathan

[oldcorollas]

it sounds exactly like the mixture is a bit on the "lean side of drivability" in the off throttle table..

i could replicate this easily with the Megasquirt when playing around... i found that after trailing throttle, if mixture was too lean, or should i say, not rich enough, then it would buck when throttle was touched... if i added in accel squirt, or decreased TPS threshold before it kicked in, i could get it to go away somewhat, but not everywhere. i found best compromise was to make trailing throttle a little richer (but not actually very richer.. just.. richer) so then it would not hesistate when a little more air came in. it was definitely nowhere near the point where it would start cackling from being too rich on decel.... that was maybe anopther 30-50% fuel i am only talking about 2-5% fuel difference (which on the grand scheme of injector ability was maybe 1-2% duty maximum change i made)

i doubt it is TPS, as the amount of throttle input should not be enough to engage the accel squirt.... so it is a purely table based issue, which is why it happens with both ECU's but of course i could be very wrong

so yeah, i would suggest it is less TPS, and more to do with the mapping in that part of the table (ie lower kPa than cruise since it is trailing throttle)..

you could also move TPS around see if it changes it, or measure resistance with rotation.. if it is a smooth change, no jumps, then it is probably ok.