tps evaluating for ii issues

[SportsterDoc]

Dave, you are the one doing all the work...we are just coaching!

These tests do not involve the mounted TPS, just the TPS connector, unplugged.

Popgun or Max may have some advice on access to ECM. Peter Baron is good with identifying pin locations, etc.

[peterbaron]

Let me know if you need a little tutoring/pic/diagram as to how to read and understand/decipher electrical connector. Will do my best (weekend)

pb

[Lord Popgun]

The ECM is under the fuel tank and easy to see and get to with the tank off the bike. I’m not sure if you can get to it by just lifting it up. I haven’t done that in a long time.

[dave]

These tests do not involve the mounted TPS, just the TPS connector, unplugged.

Hi Doc. Thank you for that clarification. I mistakenly thought you were asking me to measure the resistance at the TPS sensor itself, while unplugged. Probing the sensor connector pins while disconnected, and with the sensor still mounted on the bike would be very challenging. Measuring the resistance of the wire harness won't be that hard, I'll just need to drain my tank before I remove it. Does the FSM identify the pin locations at the ECM? I have the FSM that I can reference.

[SportsterDoc]

These tests do not involve the mounted TPS, just the TPS connector, unplugged.

Hi Doc. Thank you for that clarification. I mistakenly thought you were asking me to measure the resistance at the TPS sensor itself, while unplugged. Probing the sensor connector pins while disconnected, and with the sensor still mounted on the bike would be very challenging. Measuring the resistance of the wire harness won't be that hard, I'll just need to drain my tank before I remove it. Does the FSM identify the pin locations at the ECM? I have the FSM that I can reference.

Yes
My post 59, A-C, notes the wire color changes to the ECM and the pin numbers, from the TPS diagnostics pages in the FSM, which show the pin locations.

[dave]

Hi Doc. First, you are correct, I mistakenly identified the Black/Yellow wire as Red/Yellow, sorry.

It appears that based on my voltage test results, my TPS is functioning normally – do you agree with this statement? I used the bike to run some errands the evening after I performed the TPS tests and it ran well - idling at 1,050 RPM at each stop. I rode about 12 miles, made three stops where I turned the engine off, and stopped about a dozen times at stoplights. Maybe disconnecting and reconnecting the TPS sensor improved a faulty connection? It’s too early to tell.

I went back and reread your posts; post #58 is describing a TPS resistance test. Is this test just confirming the voltage test results at the Black/Yellow wire? Connecting the VOM probes to the TPS while the TPS is installed on the bike will be very challenging. Can this resistance test be performed with the TPS connected to the wire harness?

The resistance tests you describe in post #59 sound pretty straight forward; I think the most difficult part will be removing the gas tank. I’ll try to perform the post #59 tests this weekend.
Thanks again for all your support, Doc, Max, and Popgun.

[max]

Here is something to think about, today i replaced my tps with a potmeter to see what would happen if the voltage to the ecm was changed.
Adjusting voltage low had no effect on the rpm but lit up the check engine light below 0,3 volts, but adjusting the voltage higher dropped the rpm low by an adjustable amount and suddenly without the check engine light indicating at all.

Is this what happens to you, Dave?

https://youtu.be/Jvi3pWF5rbQ

max

[dave]

Adjusting voltage low had no effect on the rpm but lit up the check engine light below 0,3 volts, but adjusting the voltage higher dropped the rpm low by an adjustable amount and suddenly without the check engine light indicating at all.

Is this what happens to you, Dave?

Hi Max. When my RPM goes low there has never been any warning lights at all. Can you tell us what voltage resulted in what RPM? 700 RPM seems to be the magic, low RPM number for most of us experiencing the LOW RPM condition, and I wonder if this corresponds to the maximum battery voltage. Thanks Max.

[SportsterDoc]

Hi Doc. First, you are correct, I mistakenly identified the Black/Yellow wire as Red/Yellow, sorry.

It appears that based on my voltage test results, my TPS is functioning normally – do you agree with this statement? I used the bike to run some errands the evening after I performed the TPS tests and it ran well - idling at 1,050 RPM at each stop. I rode about 12 miles, made three stops where I turned the engine off, and stopped about a dozen times at stoplights. Maybe disconnecting and reconnecting the TPS sensor improved a faulty connection? It’s too early to tell.

I went back and reread your posts; post #58 is describing a TPS resistance test. Is this test just confirming the voltage test results at the Black/Yellow wire? Connecting the VOM probes to the TPS while the TPS is installed on the bike will be very challenging. Can this resistance test be performed with the TPS connected to the wire harness?

The resistance tests you describe in post #59 sound pretty straight forward; I think the most difficult part will be removing the gas tank. I’ll try to perform the post #59 tests this weekend.
Thanks again for all your support, Doc, Max, and Popgun.

Yes, as best as can be determined remotely.

Hi Doc. First, you are correct, I mistakenly identified the Black/Yellow wire as Red/Yellow, sorry.

It appears that based on my voltage test results, my TPS is functioning normally – do you agree with this statement? I used the bike to run some errands the evening after I performed the TPS tests and it ran well - idling at 1,050 RPM at each stop. I rode about 12 miles, made three stops where I turned the engine off, and stopped about a dozen times at stoplights. Maybe disconnecting and reconnecting the TPS sensor improved a faulty connection? It’s too early to tell.

I went back and reread your posts; post #58 is describing a TPS resistance test. Is this test just confirming the voltage test results at the Black/Yellow wire? Connecting the VOM probes to the TPS while the TPS is installed on the bike will be very challenging. Can this resistance test be performed with the TPS connected to the wire harness?

The resistance tests you describe in post #59 sound pretty straight forward; I think the most difficult part will be removing the gas tank. I’ll try to perform the post #59 tests this weekend.
Thanks again for all your support, Doc, Max, and Popgun.

Black/yellow is 5 vdc power to the sensor.

Resistance is measured between the sensor pins to which black/red signal output and black/green ground wire would be connected...but resistance is measured with the unit isolated/unplugged. I would probe by feel.

What the FSM does not state:

a. Operate the throttle while testing and look for a change from 1.5 K ohm high range (throttle closed = 0.5 vdc, when connected and powered) to 0.5 K ohm low range low range (throttle wide open = 5.5 vdc, when connected and powered). Key is off, TPS is disconnected.

b. Do the same test with ground connected to battery negative, instead of black/green pin, to determine if black/green is low resistance to ground.

The resistance test is redundant to the output signal voltage measurement. A smooth change is important.

Hi Doc. First, you are correct, I mistakenly identified the Black/Yellow wire as Red/Yellow, sorry.

It appears that based on my voltage test results, my TPS is functioning normally – do you agree with this statement? I used the bike to run some errands the evening after I performed the TPS tests and it ran well - idling at 1,050 RPM at each stop. I rode about 12 miles, made three stops where I turned the engine off, and stopped about a dozen times at stoplights. Maybe disconnecting and reconnecting the TPS sensor improved a faulty connection? It’s too early to tell.

I went back and reread your posts; post #58 is describing a TPS resistance test. Is this test just confirming the voltage test results at the Black/Yellow wire? Connecting the VOM probes to the TPS while the TPS is installed on the bike will be very challenging. Can this resistance test be performed with the TPS connected to the wire harness?

The resistance tests you describe in post #59 sound pretty straight forward; I think the most difficult part will be removing the gas tank. I’ll try to perform the post #59 tests this weekend.
Thanks again for all your support, Doc, Max, and Popgun.

Not certain that is necessary, since you have 5 vdc to sensor and outputs are normal. However, for an intermittent issue, checking the wiring would be the final step.

This is my 3rd EFI bike, but I hesitate removing the tank due to concern for reconnecting the fuel line properly...it could leak or pop off. However, removal will be necessary for fully checking the IACV. Removal is page 5-55 of FSM.

Max: Please verify, but I understood you to think that no further testing, beyond resistance tests, are necessary, which would let us move on to the IACV...which has only one DTC:

29-1

Loose or poor contact
IACV or circuit issue

Symptoms are engine stalls, hard to start, rough idle.

[max]

Dave, looking at another video that i did not use the 700 rpm started at 0.80 volts and by 0.925 volts the engine died at 450 rpm.

Question for you; what can cause the tps sensor signal wire ( black/red ) voltage to rise above 0.5 volts if the tps is in the idle position?

The 5 volt supply to all sensors is generated and stabilized by a special circuit within the ecm ( computer ) and will be maintained at 5 volts exactly even at very low or high battery voltage, a sign of the 5 v dropping below operating condition is the meters and fuel pump cycling after and during an engine start, so even a bad battery will result in a stable 5 v supply.



Max: Please verify, but I understood you to think that no further testing, beyond resistance tests, are necessary, which would let us move on to the IACV...which has only one DTC:

Doc, that is a very important question;

The tps voltage/resistance testing was LIKELY NOT TO SHOW A FAULT.
The important thing is to eliminate the tps/wiring fault all together by disconnecting it, only when we determine the fault has disappeared it's time to find the actual cause.

That is why i asked Dave to unplug it and ride for an extended period at least 5 times, starting with post 1 of this thread, after 4 weeks i am still waiting for that moment.

The trick with intermittent faults is to wait until it happens frequently enough to enable to locate the source of it,
waste of time testing something that works fine at the time of testing, you need to catch it when the fault is present.

As you may remember jdvalero fixed his high idle to date by locating 2 "low tps voltage " fault codes and traced it back to a rotated pin inside the tps connector; http://cb1100forum.com/forum/showthread....#pid187614 if you look at post 52 he shows the connector; http://cb1100forum.com/forum/showthread....#pid187944

For tps- idle relation have a look at this video, you can spool to 26 minutes into the video if you don't want the whole thing, the guy with the cap is keith, he is the clever dude with a lot of experience; https://www.youtube.com/watch?v=NWdOASlI0GA

max