BT 20V TPS tuning

[tofu20v]

Hiya, I'm trying to get my BT engine running as best as it can in my AE86. It's on a stock A/T ECU right now (was running a HKS piggyback but I removed it) and it has a bit of a "wall of hesitation" around 2k-3k rpms with wide throttle applied. I'm wanting to check my TPS has the right readings, it looks slightly like it's been moved by someone before.

I tried following the FSM for this, but there is no IDL wire on my TPS harness, and that's most of what you need to check with the FSM. Is this uncommon/an issue? I found someone saying the blacktop ECU doesn't have an idle switch on another thread.

Currently, with a multimeter hooked up set to 2k ohms reading and with the negative/COM wire on the E2 pin of the TPS unit, I only get a reading if I touch the positive end of the multimeter to the VTA pin.
Now with the car off - no feeler gauge put anywhere (I'm not exactly sure WHERE to put one, but I think I can under TB #1's stop lever underneath the ITB assembly), I get a reading of 0.6, and if I gradually open the throttle a bit then it will increase to 2~ until hitting infinite resistance i.e the 1. reading.

Am I on the right track here for this? I've seen in videos with 16v 4ages that people try to get the TPS to the exact spot where there resistance hits infinity with a feeler gauge under the throttle stop. I'm not sure if this same method applies for the 20vs with ITBs or not.

Thank you for any insight

[jondee86]

Cheers... jondee86

[totta crolla]

What happens if you very slowly increase the power through the problem rpm area?
It may or may not be an acceleration correction problem.

[jondee86]

I remember BT hesitation being a hot topic at one time... common problem with transplants and modified cars.
Some chat here... https://www.club4ag.com/forums/viewtopic.php?t=17124

Good luck... jondee86

[tofu20v]

> What happens if you very slowly increase the power through the problem rpm area?
It may or may not be an acceleration correction problem.

It's totally fine doing this, gradually getting on the throttle carefully. I recently had an MOT test and my friend suggested my idle emissions showed it was running pretty lean, and thinks this could be to do with my issue. Image of the results below.

https://imgur.com/iC6wCPC

I'm gonna check out that thread jondee, as for the image from the FSM, I have looked at this in detail for quite a while but still find it unclear (due to the pins being different from what the FSM thinks there should be for a blacktop). Appreciate the help though.

[jondee86]

I'm gonna check out that thread jondee, as for the image from the FSM, I have looked at this
in detail for quite a while but still find it unclear (due to the pins being different from what
the FSM thinks there should be for a blacktop). Appreciate the help though.

Actually... I just had a look at the pinouts for the BT ECU and I don't see a pin for the IDL switch.
So maybe the BT didn't use that pin on the TPS. AFAIK the idle on the BT is controlled by the
ECU opening or closing the ISCV via the RSO and RSC outputs. It looks at the engine RPM from
the crankshaft position sensor and adjusts the ISCV to bring the RPM on target.

Running lean may be your problem as I recall that replacing the O2 sensor helped some guys
with mid-range hesitation. See if you can find a workshop with an exhaust sniffer that can
check your AFR's. Best do that before buying a new O2 sensor One other thing you can try is
see if you can get the car to run with the hose off the MAP sensor. I did that once on my 16V
and it ran very rich (rough) at idle but pulled hard once it got into the mid range. If you try
that and you don't get the hesitation, then an adjustable FPR could be your answer.

Cheers... jondee86