So I did something careless while cleaning the carbs. I had ordered replacement OEM screws for the TPS along with some other OEM screws as part of my carburetor overhaul. I removed the TPS to clean them, and then screwed it back in with the nice new screws. It sure looked great!
However, since I hadn't read the haynes manual about this component, I didn't realize I was supposed to a) not take it off unless "absolutely necessary", and b) if it is going to be taken off, to make some markings so that it can be re-attached in the exact same position. I basically just shoved it on and tightened it into place with my shiny new screws.
Would failing to restore the TPS to exact same location cause any problems for the bike?
Some more stuff that's happened since I finished cleaning and re-attached the TPS in a random position:
I got everything re-assembled, and took it for a test ride. It was a pretty rough ride, and didn't feature very good throttle response. I could roll on the throttle but not get a corresponding punch of power. I hadn't assembled the carbs correctly (put the diaphragm caps on backwards :oops: ) and I hadn't tightened down the left engine intake clamp properly, which I confirmed upon getting home by spraying some carb cleaner on the intake and immediately the engine RPMs increased.
So anyway, I took everything out again, re-oriented the diaphragm caps, adjusted my mixture screws to 3 full turns out, adjusted my throttle cable so that it was snappier, re-set the idle adjustment screw to neutral. Attached vacuum tubes to the left and right-carbs to perform a carb-sync. Tightened the clamps on the intake real tight.
Started it up and got very low vacuum reading:
http://i.imgur.com/wI1cxt8.jpg
The text in that red zone "LATE VALVE TIMING OR LEAK AT INTAKE MANIFOLD OR HEAT RISER".
I ruled out the leak at the intake boots by spraying them while the bike was running: no increase in engine speed.
The engine was misfiring and there were mini-explosions occurring in the airbox.
Did some googling, and found this post from adidasguy (RIP) which I THINK explains the low vacuum and backfiring:
http://gstwins.com/gsboard/index.php?topic=66330.msg797594#msg797594
I neglected to re-attach the drain hose :ops: . Will take everything apart, slap that thing back on and see what happens.
I can't stand how difficult it is to work with this airbox, and as I mentioned in another post I'm ready to lunchbox it and trash the big bulky airbox.
Man this thing aint got no TPS ...
Cool.
Buddha.
Maybe it's been modded?
The throttle-position sensor is located on the right side of the 2001+ carburetors. On the wiring diagram, the three wires from the TPS feed into the "Ignition Control Unit". It's unclear to me what effect this component has, if any at all.
I've read that TPS influences the ignition timing. I've also read that unplugging has no noticeable effects at all. I don't know if this thing actually does something or not.
I've also read that the TPS is an integral component in Fuel-Injected engines (which obviously doesn't apply here) and that it also might have something to do with emission control (and, since I removed the PAIR valve, that ALSO doesn't apply here).
If the electrical signal from the sensor does impact ignition timing, then I definitely want to restore it to it's proper alignment. Maybe it does nothing at all and was just slapped to appease the EPA. Maybe we'll never know.
Its tricky.......you need an ohmmeter and unless you are shaZam! hot with sums, a calculator.
With the throttle closed you need to see a resistance figure of 3.5K to 6.5K ohms across the two outer terminals.
At full throttle you need to see a figure of 75% of the first resistance figure across the rear and middle terminals.
It will take you 3 or 4 goes to get it right.
Getting meter probes in there is almost impossible, best way is to stick pins in the cables and use croc clips on them.
Latest Haynes covers the procedure in detail.
Have you noticed from the wiring diagram that the ECU also needs to know what gear the bike is in? This together with the TPS and the PAIR system is Suzuki's attempt to get a 40 year old engine to meet emission regs. Maybe there might not be any noticeable drop in performance by removing these things but it WILL result in the bike pumping more shaZam! into the atmosphere. Personally I think these things are there for good reason and that they benefit everyone who breathes air!! but If you want to give it all the finger and can live with this and the potential legal issues involved with tampering with emission equipment its entirely up to you.
13 total wires go into/out of the Ignition Control Unit
http://i.imgur.com/8O9CG7Z.jpg
Red, blue, and black
to/from the TPS
Black/yellow, and white
from the RH and LH ignition coil/spark plug, respectively
green/black
to a solenoid
orange/white
to the solenoid, and to the RH and LH ignition coils
black/white
goes to a lot of components, but the sidestand switch is probably the relevant one
brown, and black/blue
to and from the pulse generator coil
black/red
from the Tachometer
red/black and green
to/from the Neutral Switch
It doesn't look like the current gear would affect it.
My new filter arrived today, so I'll be taking off the carbs anyway. I'm hoping that I'll be able to see some distinguishing marks which might clue me into it's prior position, and try to re-align based on those. Fingers crossed
My friend has some experience as an electrician so I'm sure he has an ohmmeter. I'll test it out sometime soon.
Quote from: bertreynalds on November 18, 2015, 03:16:14 PM
red/black and green
to/from the Neutral Switch
It doesn't look like the current gear would affect it.
I see a blue, a red with black hoops and a green going to the neutral switch.
Now ask yourself..........Why would a neutral switch need three wires? and why do 2 of them. feed straight back to the ECU?
There is a common wire that circuits with one of the others when in 1st gear and circuits with the other when in 2nd gear.
Check out a schematic from a GS5 that doesn't have a TPS, note the switch has a single blue wire that grounds out through it
This is an F version.
Remove all that E-crap, unplug the TPS and advance the timing by slotting the timing pickup plate screws.
With the Pair system active the Ignition (ECU) box would: allow air into the exhaust stream to help the Catalyst
lower the carb needles to lean out part throttle mixtures
and retard timing (maybe, havent tested that)
As you have already disconnected Pair and mis-adjusted the mixture screws from oem (did you have to remove the anti-tamper caps?)- the bike no longer meets the oem emissions targets and the subsequent anemic performance of the stocker. Its time to finish the job and lose the airbox if your going with a lunch box, lose the excess of vacuum tubing, and jet it like a real bike. 4-6 degrees of timing advance wont hurt it either, makes it snappier off of idle and helps fuel economy - which ultimately helps emissions :cheers:
Rant off
So I did a little more research.
http://www.bikebandit.com/oem-parts/2004-suzuki-gs500f/o/m6061#sch503304
Goddamn they added a lot of shaZam! onto these carbs for the 2004 model-year. I'm guessing that the absence of a 2003 model is because they were trying figure out how to make this thing EPA compliant going forward.0
Note items 47 and 57 on the parts fiche.
57, what this thread is about, is the Throttle Position Sensor. It is connected to the ICU (ECU?) by three wires.
47, is the "Vacuum Control Valve". What the hell is this you ask?
I BELIEVE that this is the "solenoid" in the top-left of the wiring diagram:
http://www.manualslib.com/manual/791753/Suzuki-Gs500-F.html?page=27#manual
which is also wired into the ignition control. The following is my theoretical understanding of all this extra crap on the 2004+ carburetors:
All the vacuum hose crap they added on this FK4 model is supplied by the right carb vacuum port. This vacuum operates the frame-mounted petcock, and the same vacuum line triggers the PAIR valve to inject air in to the exhaust system. This vacuum line runs through a one-way valve, and then is also connected to the vacuum damper. Finally, it enters the IN port of the Vacuum Control Valve. What happens now is referred to in the Haynes manual as a "piston lift control system".
This valve is operated by electrical signals that are part of the ICU circuit. When it is activated, it sends a pulse of vacuum to the white ports on the diaphragm caps. This vacuum has some sort of effect on the timing of the pistons in the carburetors. What EXACTLY that effect is, I don't know. Perhaps it makes for snappier throttle response by pre-lifting the pistons when it detects that the throttle position has increased. Perhaps it smoothens out the effect when the throttle is released at higher engine speeds, so if you're running at 3/4 throttle and then let it snap back, it doesn't immediately plunge the needles back in and cause violent deceleration.
I'm not an engineer, nor do I understand the effects of the above on emissions, which were likely the primary impetus for the implementation of this system. All of this is theoretical.
Can someone help me as well bike won't start and need a walk through