Would You Replace This Tps?

[Shaun Ketterman]

Hello Again!

Tested most of my sensors as best I could with a multimeter, as the Busa is idling rough and the revs tend to fall slowly and/or hang.

TPS Sensor:

1. Resistance w/ throttle closed: 1.17k ohms (service manual shows it should be 1.3k ohms)
2. Resistance w/ throttle wide open: 3.9k ohms (service manual shows it should be 4.5k ohms)

3. Input voltage (red wire in harness / good ground): 2.1V (manual states 4.5V - 5.5V) *****
4. Input voltage (red wire and black wire in harness): 5.0V (same as above)

5. Output voltage - Don't know how to test this.

***** I'm not entirely convinced I'm using a 'good ground' to test the input voltage as in #3, and the huge difference in the reading may suggest that the ground I used was not good enough? What constitutes a good ground for testing voltage and continuity? Are the low ohms enough justification to replace this thing? Would these numbers equate to my rough idle and slow deceleration/hanging revs? Thanks!


Shaun

 

[RansomT]

Output voltage is on the orange/black wire (IIRC). Key on and just move the throttle. Idle (no throttle) should be 1.0v there abouts and WOT should be 4.2V+ or so. And it should move "smooth" up the scale as you open the throttle.

 

[Shaun Ketterman]

Output voltage is on the orange/black wire (IIRC). Key on and just move the throttle. Idle (no throttle) should be 1.0v there abouts and WOT should be 4.2V+ or so. And it should move "smooth" up the scale as you open the throttle.

Thanks Ransom. So red lead on the orange/black wire, and black lead to ground?

 

[David Offor]

Just did a retest on mine, give you something to compare against.
My Haynes manual says approx 1.3ohms closed and approx 4.5ohms open.
Also, a (possible) way to test for a TPS, causing a hanging throttle problem, is to open the throttle wide (with the multi meter connected) and let the throttle Spring shut (as per the video), your meter should show the reading drop straight back, to its closed reading, if it stops higher, then that could be your cause, it's just a thought I had but I'm not 100% sure that it's a reliable test for your sticking revs issue.
Another thing that you can check, while your meter is connected, is opening the throttle very slowly, a dead spot in the TPS will show up as, twisting with no reading change and then suddenly the number jumps to a higher number or inconsistent increment advancement 1,2,3,6,9 for eg, it's a little difficult to twist so slowly but it's a benchmark test.

 

[Shaun Ketterman]

Just did a retest on mine, give you something to compare against.
My Haynes manual says approx 1.3ohms closed and approx 4.5ohms open.
Also, a (possible) way to test for a TPS, causing a hanging throttle problem, is to open the throttle wide (with the multi meter connected) and let the throttle Spring shut (as per the video), your meter should show the reading drop straight back, to its closed reading, if it stops higher, then that could be your cause, it's just a thought I had but I'm not 100% sure that it's a reliable test for your sticking revs issue.
Another thing that you can check, while your meter is connected, is opening the throttle very slowly, a dead spot in the TPS will show up as, twisting with no reading change and then suddenly the number jumps to a higher number or inconsistent increment advancement 1,2,3,6,9 for eg, it's a little difficult to twist so slowly but it's a benchmark test.

Nice! Thanks David. So how in the world do you get the leads to stay in the connectors without holding them? The harness connectors on my '07 are so small that the leads don't fit inside. I basically have to put some pressure on the leads and physically hold them 'in' the connector. And let me tell you, holding both of those leads like that, while trying to simultaneously twist the throttle, and read the multimeter, is a freakin' chore. Since the wife and kids should be back from a family visit today, I can probably enlist the help of my 8-year old ;-) I'll give the video a watch when I get home, and hopefully get that test complete. Thanks again!


Shaun

 

[David Offor]

I use 'wishfully thinking and hope', it's a bit of a balancing act tbh.
8year olds tend to have small fingers, good eyesight and do as they're told, maybe the reason they make such good 'sweat shop' workers, anyway, going off topic a tad.
It would be nice if you can eliminate the TPS, one way or another, good luck.

 

[David Offor]

Another possible cause of your rough running, could be leaking injectors, just a thought, people have said, that failing injectors throw up so many problems, thats the route I'm going down, for my problems at the moment, I have a confirmed good set on the way, hopefully by Friday, I'll have some good news and if it's not injectors, all that is reallistically left, are the coils.
Hoping for good news, for us both.

 

[RansomT]

Thanks Ransom. So red lead on the orange/black wire, and black lead to ground?

Yes. The only bike I have here at the house is my nitrous bike and it has been re-wired / modified so many times, I can't give you a for sure answer on the color of the positive lead. My spare shop manual is at the garage. Ground the black lead and then probe the other wires, the one that changes from 1.0-4.0v is what supplies the signal to the ecu.

 

[Shaun Ketterman]

Just did a retest on mine, give you something to compare against.
My Haynes manual says approx 1.3ohms closed and approx 4.5ohms open.
Also, a (possible) way to test for a TPS, causing a hanging throttle problem, is to open the throttle wide (with the multi meter connected) and let the throttle Spring shut (as per the video), your meter should show the reading drop straight back, to its closed reading, if it stops higher, then that could be your cause, it's just a thought I had but I'm not 100% sure that it's a reliable test for your sticking revs issue.
Another thing that you can check, while your meter is connected, is opening the throttle very slowly, a dead spot in the TPS will show up as, twisting with no reading change and then suddenly the number jumps to a higher number or inconsistent increment advancement 1,2,3,6,9 for eg, it's a little difficult to twist so slowly but it's a benchmark test.

Your Haynes manual matches my Clymer with the numbers. I retested the resistance again just now, and still showing the same as before. So my resistance is low. I also did the task with opening the throttle slowly all the way and letting it snap shut. Numbers on the multimeter went up nice and smooth, and took a split second to get back down to idle numbers, so I think I'm good there.

Another possible cause of your rough running, could be leaking injectors, just a thought, people have said, that failing injectors throw up so many problems, thats the route I'm going down, for my problems at the moment, I have a confirmed good set on the way, hopefully by Friday, I'll have some good news and if it's not injectors, all that is reallistically left, are the coils.
Hoping for good news, for us both.

Yes. I can't wait to test my injectors. I have this motion pro device on the way, which you take the injector off the bike, clamp it onto the tool, and it has a battery that initiates the injector, while you spray cleaner into the input side, and just let it spray onto a paper towel. So this basically tests voltage, clogging, leaking, and spray pattern all in one. If I have an injector that is bad, or degraded, this will prove it.

Yes. The only bike I have here at the house is my nitrous bike and it has been re-wired / modified so many times, I can't give you a for sure answer on the color of the positive lead. My spare shop manual is at the garage. Ground the black lead and then probe the other wires, the one that changes from 1.0-4.0v is what supplies the signal to the ecu.

Dude I can't even fathom nitrous. So let me ask - when you hit the spray button...I mean...what's it like?!?

My TPS has blue, black, and an orange-ish wire (this was probably red once upon a time). The blue and black wires are used for resistance and continuity, the orange one is used for voltage.

So my next question here:

1. The input voltage test requires a 'good ground' as described in my manual. When I test the voltage using the wire in the harness and (interestingly enough) the metal portion of my exhaust pipe, I get a good voltage reading (~5.0V)
2. I mention this because, to me, this suggests that I have, in fact, found a 'good ground' to test, correct?
3. Now, the continuity test also requires a 'good ground'. When I use that same area of my exhaust pipe to test for continuity, it does not work (multimeter does not 'beep'). So this *should* suggest an issue with continuity on this sensor, yes?
4. If so, and you combine that with the fact that my resistance is off by the amount in the OP, would THAT be enough justification to replace it? Or does the fact the the input voltage is good trump the continuity and resistance tests failing?

If replacement turns out to be necessary, is buying a used TPS worth it, or should I just shell out the cash for a new one? I'd really like to be certain this thing is bad. So far it appears to pass some tests (input voltage and possibly output voltage), but fails resistance and continuity.


Thanks guys!

Shaun

 

[Shaun Ketterman]

Update to add I just picked up a bunch of back probes, or whatever they are called. I want to test the output voltage on this (and anything else I can) before I decide to replace it.

 

[Shaun Ketterman]

Forgot all about this thread.

After all testing, my TPS does not pass resistance or continuity tests.

It does pass input and output voltage tests, with a smooth increase and decrease in numbers while twisting the throttle.

Are the resistance and continuity fails worth a replacement? Is a used TPS a good option?