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KProV4 - TPS and o2 Sensor Issues

Posted: Wed Nov 21, 2018 11:15 pm
by K24Miata

I have a KPro V4 installed on a PND ECU, running the K24 in my Miata. We received a base tune from the guys at KMiata, and have the car up and running. Sort of. We got the car to idle, warm up, drive into the trailer and into the exhaust fabricator/dyno tuner's shop.

Pertinent details:
Brand new RSX-S wiring harness
Brand new B-series TPS,
Brand new Denso O2 sensor for the RSX-S
brand new Honda MAP sensor for the RSX-S
74MM B series throttle body
Skunk2 Ultra Street intake manifold
RDX injectors
Hybrid Racing fuel rail
fuel pressure regulator set to 60PSI
KMiata "race" header.

A couple of problems, however.

First problem: We are using a brand new B-series TPS and a KMiata jumper harness between our brand new RSX-S wiring harness and the TPS. I was able to get a reading from the TPS on the KPro with the ignition turned on, but the engine not running. I calibrated the TPS as per the Hondata instructions. However, when the engine is running, I get a "0" value from the TPS. With the engine off, I get a TPS value. Any idea what could be wrong here? Bad TPS?

Second problem: We don't seem to be getting a good reading from our O2 sensor (brand new Denso O2 sensor). Our tuner says that the O2 sensor is giving a constant AFR reading of ~11.5 when the car idles, even if he changes the fuel map (which should obviously change the AFR from the O2 sensor). Any idea why this may be the case? Possibly related to the TPS issue? The car is running in open loop, is it possible this has something to do with the o2 sensor issue?

I have attached a data logs from one of our initial startups, in case it is helpful.

Any help the community can provide is much appreciated!

Re: KProV4 - TPS and o2 Sensor Issues

Posted: Thu Nov 22, 2018 5:46 am
by Dublocivic
As far as the 02 sensor goes, if you have run the car on an open header and the header is vibrating or shaking much at all the heater element is probably damaged. The O2 sensors are super sensitive and break very easily if they are jarred or shaken too much. Are you getting an O2 code? If so, try replacing the O2 sensor, make sure you have about 12 inches of pipe after the sensor and make sure the header or exhaust is solidly secured so that it doesnt shake or move too much. Also check the O2 wiring and make sure that it matches the sensor wiring correctly.

Re: KProV4 - TPS and o2 Sensor Issues

Posted: Thu Nov 22, 2018 4:48 pm
by K24Miata
Turns out the 2 problems were related. The TPS was installed incorrectly, so it wasn't giving a proper signal. Once the TPS was fixed and gave a reading the o2 sensor started acting normally.

Re: KProV4 - TPS and o2 Sensor Issues

Posted: Sun Nov 25, 2018 2:36 pm
by Dublocivic
Glad you got it sorted!