Trottle body STPS motor

[Idh]

I have surrendered, going into a suzuki garage to get sorted or part exed!

[Eric GSX1400K3]

Hmmm, have you checked the TPS and STPS on both the original and rebuilt throttle bodies?  each should be getting 5V input, and if you connect a multimeter across the sensor pins, and reading Ohms, you should get a steady change in Ohms as you move the little rotating bit through its motion.  Best done with the sensor off the bike and on the bench.

Watch the Ohms carefully, what can happen is that the tracks in the sensor corrode, so the signal drops away, leaving the ECU without an input, causing erratic running.

Usually a C28 code pops up, which when you read the book, is unrelated to the STPS.  I had the same as you, ended up replacing both the TPS and STPS with genuine, she runs well now.  Oh, and don't trust cheap aftermarket injectors, they fit, but don't flow enough fuel.  Make sure the fuel rail is clean, plus the in tank filter and pump assembly.  Injectors are pretty robust, mine are 24yo originals, still working fine.

[Idh]

Thanks Eric.

I have checked the ohms on each TPS and STPS on both.
I had to adjust to get the required setting. So they are good.

Not checked voltage. Will look into that.

Am tempted to replace them, but as both bodies have issues, not sure it's worth the expence just yet.

I suspect my original bodies have a power supply issue to the STPS motor.

Injectors are all original as far as I know.

[Hooli]

If you test the SPS & TPS as the manual says, there's an extra check to do.

The manual says -
Test between the power & signal leads for a smooth change of Ohms over the full sweep.

Every one I've had fail passes that test but doing the following finds a fault -
Test Ohms between the power & earth leads over a full sweep - it shouldn't change, but all the failed ones I've had do change. I think they short to the resistive track the signal wire uses.

Someone on here found the info on a GSXR forum as they use almost the same sensors.

[Idh]

Thanks for all the assistance.
I have found that the STPS motor isn't working. It's getting 5 v supply, but not moving. Can't see where I can source a new one, but will keep looking.

So I am sticking with my spare second hand set. Was running very rough but after a second balance and TPS/STPS adjustment,it's running a lot better.

My balancer is a cheapy one, so going to fork out and go through the process again.

If no  better, then this is now well beyond me, so will have to decide what to do.

Again, thanks for all the input.

Ian

[Eric GSX1400K3]

Check the large grey connector on the lhs under the cover, thats what feeds power to the various sensors up at the TB.  Could be a corroded connector or pin.  From the photos you STVA looks clean and undamaged, they're well protected up under the throttle bodies.  Maybe inspect the wiring coming into the stva.  Also, double check the main connector at the ecu under the seat, lots of small pins there, easy to get one bent so it doesn't seat home.

[Hooli]

I'll be impressed if you've broken the STVA motor, as I've never heard of that before. Except for the magnet issue mentioned earlier.

I know you said it's got 5v but is the earth ok? I believe the basic 5v signal voltage is just for the ECU to confirm it's plugged in, without a circuit at 5v you'd get the C28 error and as I recall you don't get any codes?

[GSXKING]

Sorry guys I take my hat off to you guys who delve this far in to bike faults. I've got zero clues about these things.   

[Mr Gee]

Sorry guys I take my hat off to you guys who delve this far in to bike faults. I've got zero clues about these things.   

I second that GSXKing. 

[Irish in Oz]

Thanks for all the assistance.
I have found that the STPS motor isn't working. It's getting 5 v supply, but not moving. Can't see where I can source a new one, but will keep looking.

So I am sticking with my spare second hand set. Was running very rough but after a second balance and TPS/STPS adjustment,it's running a lot better.

My balancer is a cheapy one, so going to fork out and go through the process again.

If no  better, then this is now well beyond me, so will have to decide what to do.

Again, thanks for all the input.

Ian

I had a throttle body in my hand a couple of days ago and to me it is a solenoid so it gets its voltage from the ECM depending on temperatures from other inputs, you should get a reading across the coil. You could put an external voltage 6 volt should be ok to see it it actuates if not it may be jammed or even the throttle body shaft.

[Idh]

OK. So, after all this time, there is a fault in the loom of my original throttle body. So, I have tested it on the loom of the spare body and the lead running into the STP motor has a has fault in it. So, tonight is swapping everything over and balancing and TPS/STPS adjustment.  I might be liking her again by the weekend!

[Hooli]

Nice find, I've not seen that before but the wiring on these is getting older after all.

[Eric GSX1400K3]

Good find.  I have noticed that some of the wires are tight, especially the wire leading from the lh grey connector to the stps sensor if its not routed correctly.

[Idh]

Throttle bodies in.
Balanced as best I can with a cheap guage
TPS set to 1102 ohms
STPS set to 803 ohms with valves closed.

I really didnt think I could make it any worse   but apparently I can!

Missing a cylinder or 2 when running,  even at high revs.

Think I am done. Not even running well enough to hide as a trade in!!

[Hooli]

FFS what a  moment!

Without seeing it, it's hard to suggest anything as you've gone through loads of stuff already.