Advice on waveform Harley TPS

Ask for and share advice on using the PicoScope kit to fix vehicles here.
Post Reply
baging
OneWave
OneWave
Posts: 16
Joined: Wed Feb 22, 2012 8:45 am
Location: Sweden

Advice on waveform Harley TPS

Post by baging »

Hi all,

Working with a Harley Davidson at the moment which can't produce a stable TPS signal
Replace the TPS sensor, but it's still all over signal wise...
Connected my Pico yesterday and from what i can see it got some interference? Or what am i looking at?

Attaching 2 images. The stable one is with engine off and the interfered one is with engine running...

/Stefan
Attachments
20130702-0001.gif
20130702-0005.gif

KimAndersen
TwoWaves
TwoWaves
Posts: 246
Joined: Fri Nov 30, 2012 2:53 pm
Location: Denmark

Re: Advice on waveform Harley TPS

Post by KimAndersen »

Hi

Which Harley Davidson model are we talking about ?

Are there any faults with the bike right now or are you just curious to know how the TPS sensor are operating ?

I would look after those wires that runs along throttle position sensor and specially the ignition wire that goes to the ECU. :wink:

Regards
Kim

baging
OneWave
OneWave
Posts: 16
Joined: Wed Feb 22, 2012 8:45 am
Location: Sweden

Re: Advice on waveform Harley TPS

Post by baging »

Thank you for yor quick reply!! :)

This is an 2004 Ultra CVO 103" which has a history of missing/stutter at times, but not always.
Problem emerged when i was trying to map the ECU and discovered that the TPS was all over the place.
Done all the tests suggested by the Harley service manual, but can't find any faults there.
All relevant wiring to/from TPS is checked and can't find anything there.

Never had the need to check a Harley TPS with my Pico before, so in a way i'm curious to know if i'm looking at an ok waveform? Used the scope on several other TPS'es, but none of those have shown this kind of interference....

Rgds /Stefan

KimAndersen
TwoWaves
TwoWaves
Posts: 246
Joined: Fri Nov 30, 2012 2:53 pm
Location: Denmark

Re: Advice on waveform Harley TPS

Post by KimAndersen »

Hi stefan

Despite your hard effort to solve this running issue i would still be looking at the wiring net and how the sensor gets power and ground.

I don´t have a wiring digram over that particular model but can see on other harley models that the ground connection from TPS sensor are connected to the oxygen sensor and the coolant temp. sensor and so maybe it could influcence the TPS sensor, if you have a bad oxygen senor or a bad coolant sensor.

You could try to temporary disconnect these sensors.

Regards
Kim

Chris_W
OneWave
OneWave
Posts: 20
Joined: Tue Oct 02, 2012 6:16 pm
Location: Lincolnshire

Re: Advice on waveform Harley TPS

Post by Chris_W »

I know nothing about Harleys but have an observation.

That interference is very regular. Count it up, 12 times per second. 4 stroke twin? So 1 fire per rpm...

What's the idle speed....

SamP
Newbie
Posts: 4
Joined: Mon May 06, 2013 5:49 pm

Re: Advice on waveform Harley TPS

Post by SamP »

Hello buddy, it seems like some other circuit component is pulling TPS to ground so 1+ with wiring tests.
Just unplug other sensors in line and see whet happens.
Regards

baging
OneWave
OneWave
Posts: 16
Joined: Wed Feb 22, 2012 8:45 am
Location: Sweden

Re: Advice on waveform Harley TPS

Post by baging »

Thank you all for your input!

I'll definitely check the other sensors and their wiring and get back to you with the result! :)
Great forum! Quick, relevant answers!!

Chris W: Yes, 4-stroke twin and idle is 1000 rpm

User avatar
Fat Freddy
TwoWaves
TwoWaves
Posts: 335
Joined: Fri May 04, 2012 4:52 am

Re: Advice on waveform Harley TPS

Post by Fat Freddy »

Can you post the data files.

FF

arjen
TwoWaves
TwoWaves
Posts: 53
Joined: Wed Mar 06, 2013 7:18 pm
Location: Drachten, Holland

Re: Advice on waveform Harley TPS

Post by arjen »

You can scope power and ground to see if they are stable.
If they are, then place breakout leads between tps and the connector. Connect power and ground but leave the signal wire disconnected to see if the signal is good then.

baging
OneWave
OneWave
Posts: 16
Joined: Wed Feb 22, 2012 8:45 am
Location: Sweden

Re: Advice on waveform Harley TPS

Post by baging »

Thanks again!

I had to put the bike away for a few days (overswamped with other bike related work right now), but will continue next week.... I'll get back to you with my findings! Thanks all!! :)

Post Reply