jrock

So I replaced my TPS sensor and my 4runner is still not going into open loop. My problem is that my TPS sensor is not showing the correct throttle position. Wide open only reads about 30% or little higher versus the 80% it needs to see so that the computer switches to open loop. This is preventing me from tuning my supercharged engine to run proper AFRs!! Robbed of HP dang it.
anyone out there know how to fix this?
throttle cable is normal tension...
thanks.

mt_goat

Subscribed, I'd like to know too. I have the opposite problem, I go into open loop too easy.

jrock

so does your throttle position show a higher % than you think you are applying? Ex...while barely pressing the pedal your scanner shows 80%?

mt_goat

No, not that I've noticed. I'll take note of that next tuning session. I think something else is throwing it into open loop. I'm not sure what.

TrackRunner

jrock: I was having open loop issues with my 4Runner as well. I could only get into open loop if i was WOT (WOT registered as 75% throttle position on my scanner btw). You may want to try swapping your throttle body assembly (sensors and all) with a friend if you can. That way you don't waste a lot of time & money replacing sensors that work fine (what I did lol). Fortunately, there may be a solution for you out there even if you cant fix your TPS issue. URD just sold me a 02 calibrator made for later year 4runners that have two 02 sensors. Once installed, this little box really made the difference for me.

Before: 14.7 AFR all the way from 20in. Hg to 8PSI of boost.

With the 02 calibrator: 14.7 AFR all the way from 20in. Hg to 0PSI. From 1PSI to 8PSI the fuel gradually gets richer down to 12.1 AFR.

(I never went WOT for these results, and my truck stays in closed loop for the duration of the runs)

I just put the 02 calibrator on last Friday, so I am still testing it out. URD should be putting it up on their website soon as well. Good luck!

mt_goat

You mean this?
http://www.urdusa.com/product_info.p..._id=1230100028

I've been running it too.

TrackRunner

mt_goat: not quite that, but pretty much the same functionality. A few of us later year 3rd gen owners still have two 02 sensors (fed. emissions) on our trucks, not one 02 sensor and one AFR sensor (Cali spec.). URD made a 02 sensor calibrator for early year 3rd gens, but when installed on the later year runners it didn't work right (This calibrator was removed from their site about two weeks ago, it was called the ESC1) The product that I am now running works on all the 3rd gen 4runners equipped with two 02 sensors.

Edit: Dale, I noticed that you have a 93. Are you sure you have an AFR sensor? Maybe running the AFR calibrator on an 02 sensor is what's causing your open loop issue.

mt_goat

Ok gotcha. Pretty sure about the A/F ratio sensor, I removed it from a 2001 Tacoma, along with the engine, transmission, and ECU. All came from the same truck with only 27,000 miles on the ticker. All looked to be factory and I labeled the front and rear to keep them from getting mixed up. How could I tell for sure?

TrackRunner

ahh ok, I didn't realize you did a swap. That changes things up. If it is a 2001 I'm pretty sure you do have the AFR sensor.

If you still want to check:

mt_goat

Thanks, yeah I want to check. Both my front and rear sensors have 4 wires going to each sensor, I guess that's what Brian meant in that quote.

TrackRunner

Interesting. If there are the same number of wires, it seems like you should have matching sensors. That might mean you have two 02 sensors, but I'm really not sure. You could always pull the front sensor and get a part number off of it. That way you'll know for sure. Might be worth it, because I'm sure putting an AFR calibrator on an 02 sensor can't be a good thing. If you truck is running fine though, it is probably an AFR sensor..

mt_goat

Yeah the truck runs great, no codes. I wonder what Brian meant by contacts, where did you copy his quote from?

TrackRunner

cool man, it's always nice to have a good running vehicle. my tranny started slipping really bad this last week; I'm taking it in for service tomorrow actually

here's a link to his post:
https://www.yotatech.com/forums/f2/7...l#post50481645

mt_goat

Oh yeah, I remember that one now. Did your truck come with 2 cats?

mastacox

Ah Dale, so I'm not sure how I missed this back then (when you were first putting all of your stuff in) but it IS possible that you have a narrow-band Oxygen sensor... If both plugs are the same, it's likely you have two NB's...

Edit- it might explain why your AFR Sensor Calibrator doesn't seem to work... as ironic as that is.

http://www.ultimateyota.com/index.ph...r_applications

TrackRunner

mt_goat: my truck only has one cat.

mastacox

Hmm, looks like the only way to tell the difference between nearrow-band and wideband sensors will be the part number... Looking around Denso Sales' page on Amazon, it looks to me like the narrow-band and wideband sensors all have 4 pins on the plug I don't suppose you can read the part numbers on the sides of your O2 sensors, can you Dale?

http://www.amazon.com/s?ie=UTF8&keyw...%20Inc.&page=1

mastacox

Oh and with respect to the original post-

Is it possible to ohm the TPS to make sure it's resistance is linear and smooth? I might consider trying something crazy like pulling the ECU fuse for a couple of minutes, and if that didn't work try unplugging the TPS, starting the engine and running it for a minute or two, and then shutting off the engine and re-plugging the TPS in?

I'm just shooting in the dark here...

mt_goat

Yeah Jrock, along with what Brian said, here's the 98-2000 Tacoma FSM instructions for testing the TPS
http://www.ncttora.com/fsm/2000/Repa...0Body/insp.pdf