Suzuki GSX-R Motorcycle Forums Gixxer.com banner

1 - 14 of 14 Posts

·
Registered
Joined
·
10 Posts
Discussion Starter #1
Odd request, but I think I have a suspect TPS..... I have other primary and secondary position sensors from K2 and K8 bikes...... Does anyone know if these are the same item re-used over the years with different loom connectors or if they have different resistance ranges? .... It would help to be able to do a substitution but I live in the middle of nowhere and even s/h TPS are expensive for a two minute substitution test!.... So hoping to be a le to use ones of the ones I have sitting about
Cheers
K
 

·
You should listen to me. No, seriously, listen to
Joined
·
7,701 Posts
I couldn't find a resistance spec for the K9 secondary sensor. I'm guessing that it's 5000 ohms like the K6. The output voltage range has shifted up from .5 - 3.9 V to .7 - 4.1 V. Not encouraging but not a deal breaker for a quicky test. If the connectors match and you have some time, I'd be inclined to give it a try. TPS seems to be more different, including connectors.
 

·
Registered
Joined
·
10 Posts
Discussion Starter #4
Thanks for the info BillV..... It's looking like they changed the resistance of the various position sensors quite a bit.... Was hoping they had just stuck with something that worked.... But that's not how Japanese bike makers think unfortunately.... I don't run secondary butterflies (the motor is in a light single seater racing car ('open wheeler' to you guys I'd guess) used for tarmac speed hillclimb in the UK.... I'm in the off-season now so I'm going to go through the whole fuel system starting with pump pressure and flow.... And if there's nothing else showing then I'll come back to the TPS. 🙂

Thanks again

K
 

Attachments

·
You should listen to me. No, seriously, listen to
Joined
·
7,701 Posts
The K6 TPS resistance is 4680 ohms. I'd think that this would be a useful thing to check but it's not listed for K9. Part of the problem is that K9 has a secondary harness from the main harness to the TPS, STPS, IAT, and ECT with the leads all interconnected and Suzuki, for whatever reason, wants to do the diagnostic checks at the end of this harness instead of at the various isolated sensors. I think that this forces the checks to only be by voltage instead of additional resistance checks. I could be wrong but I'd really expect the K9 TPS to also be 4680 ohms. One thing that I'd be doing is measuring the resistance between the TPS sensor's wiper lead (P/B) and either the ground or 5V supply lead as the throttle is rotated. I'd be looking for dead spots or erratic behavior.

SDS can provide useful diagnostic insight about such things.
 

·
Registered
Joined
·
10 Posts
Discussion Starter #6
Thanks for all the info so far.... It's now got really odd.... I have a digital multimeter hooked up so I can monitor the TPS output voltage to ground.

With the ignition on and the engine not running the voltage sweeps nicely as the throttle is opened..... If I now start the engine (with everything the same) the TPS output voltage just sits there static when the throttle is opened.

This seems really strange .... Could it be a vibration issue?..... Something inhibiting the voltage when the engine's running.... Any thoughts??

K
 

·
You should listen to me. No, seriously, listen to
Joined
·
7,701 Posts
That's definitely weird. What voltage does it sit at? Measure the voltage at the R lead and see if it's anything other than 5 V. Also try measuring the voltage on the Y/W lead from the secondary throttle sensor. I'm thinking that there's some sort of short or bad connection. The most likely location is at the 3 way or the 6 way connectors associated with the sub-harness between these sensors and the main harness.

The service manual/wiring diagram suggests that the P/B lead level is not associated with a load at the ECM, i.e. that its level is not be affected by the connection to the ECM. If that's right, you ought to be able to remove the P/B lead from the 3 way connector and measure it straight from the TPS. You'll probably generate a C14 error but that's not what this is about. While the lead is removed, you could also measure the voltage on the P/B lead on the main harness side of the 3 way connector, i.e. on the lead in the main harness that runs to the ECM.

Carefully inspect the harness for damage from rubbing, etc.
 

·
Registered
Joined
·
10 Posts
Discussion Starter #8
Thanks for your patience with this Bill... Your help is much appreciated. I'm really scratching my head over this... If there's a wiring or internal TPS fault, why does the TPS output voltage just sit perfectly at the voltage it does when the throttle is closed and the ignition on.... You would expect its to float to something unreasonable if it went open circuit... 5v supply to the TPS when the engine is running will be worth a check... Checks out statically (but thinking about it, it would have to vary exactly in synch with the TPS resistance to keep the voltage steady... Seems unlikely).... As the 5v is common to lots of sensors you'd expect some other effects if it was shifting.
Unfortunately this is a race engine with removed secondary butterflies, non standard loom and no bike dash (and hence no fault codes).... It's worked faultlessly for the last 4 seasons so I don't think there's anything inherent in the mods that's causing this.... Something has recently failed (and quite possibly the TPS in some mysterious way.) Interestingly if I pull the TPS plug off and just leave it dangling the symptoms disappear.... But that's not really a solution as, although it runs better, it will be far from optimal fuelling to be actually using in anger on the track.
 

·
You should listen to me. No, seriously, listen to
Joined
·
7,701 Posts
If you can afford all that, you can afford SDS. I won't vouch for it but its available for $116 here. All you need is ECM pin 62 (grey), ground/pin 36, and (I think) 12 V/pin 12. Plus a computer to run the software. The pics are of a real SDS but I'm suspicious that they're selling something else. There are other sellers. Brand name MAOZUA is suspect as I believe that the real unit was made by Hitachi Car Engineering. The white CD that is seen in other sellers pics is definitely a copy. But if it works, who cares? Among other things, it will tell you what the ECM thinks the TPS is doing.
 

·
Premium Member
Joined
·
661 Posts
I am not really familiar with this issue, but, is there a way to put a better temporary ground or other connections? You did mention that you thought it may be vibration related. It could be not getting a good wire contact somewhere. If you have any wire connections you could clean them with some contact cleaner or sandpaper if its big enough. Also check for suspicious looking wires that are kinked or crushed. I know its basic stuff but even if it has nothing to do with the issue its good to go over. You probably have pretty good mechanical abilities if you put that motor into that car! That is sick. Do you have any videos on you tube so we can see it go?
 

·
I know things... A lot of things.
Joined
·
3,147 Posts
Where/how exactly do you measure the TPS output voltage by the way. And, as Bill already asked, what value does it sit at with the engine running?
 

·
Registered
Joined
·
10 Posts
Discussion Starter #12
Hi Guys

Thanks for your help on this... The info was really useful.
I have rock solid 5v and earth readings and have disconnected the ecm and proved the wiring end to end..... It's now almost 100% that it's the TPS... I have a replacement on the way. Many thanks for your help

Don't have any up to date vids of the car on our narrow scary hillclimbs but here's one from six years ago when I had just fitted the K9.... It's a fair bit faster now the bugs are out.



https://m.facebook.com/story.php?story_fbid=2436284156384776&id=100000096464557

Hopefully you can open it.

Thanks again

Keith
 

·
Registered
Joined
·
10 Posts
Discussion Starter #14
Thanks again for the info.... Received the replacement TPS and it solves the problem..... Now4i can get on with the other 127 items on my 'to do' list. 🙂

Cheers

Keith
 
1 - 14 of 14 Posts
Top