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Discussion Starter #1
I was reading my typically unreliable Haynes manual and it says that I need to use the Suzuki SDS box to *freeze* the Idle Speed Control valve so it doesn't work against me during adjustment of the air screws.


If I understand the ISC correctly, it's just a valve with a stepper motor inside it and it takes filtered air from the airbox hrough the center hose and lets it go out the two other hoses to the front and rear throttle bodies.

I was thinking about buying an adjustable air valve to control the air flowing into a tee fitting and hooking two smaller hoses to the front and rear throttle bodies and starting the engine and warming it up using the ISC and then switching to my home brewed manual ISC.

Does anybody think that wouldn't work instead of buying an SDS box or paying a Suzuki dealer to synchronize the TB's?
 

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I was reading my typically unreliable Haynes manual and it says that I need to use the Suzuki SDS box to *freeze* the Idle Speed Control valve so it doesn't work against me during adjustment of the air screws.


If I understand the ISC correctly, it's just a valve with a stepper motor inside it and it takes filtered air from the airbox hrough the center hose and lets it go out the two other hoses to the front and rear throttle bodies.

I was thinking about buying an adjustable air valve to control the air flowing into a tee fitting and hooking two smaller hoses to the front and rear throttle bodies and starting the engine and warming it up using the ISC and then switching to my home brewed manual ISC.

Does anybody think that wouldn't work instead of buying an SDS box or paying a Suzuki dealer to synchronize the TB's?
I'll vote that it won't work. The ISC circuit is controlled by the ECU. This circuit determines idle and low speed air flow and keeps this balanced between the throttle bodies. Doing a TBS with an 07+ SV only affects this circuit; it does absolutely nothing to the air/fuel flow above idle or just above idle.

You cannot alter this circuit without the SDS software, either Suzuki's or an aftermarket supplier like Healtech. You can mess with the plumbing all you like but it won't alter the settings in the ECU like the software can. You can mess with the bleed screws but you may make things worse because the ISC circuit will try to compensate for whatever you did. You have to cut the ISC out and then reset it to accept the changes you make, and you can only do that with the SDS as far as I know.

Synching the ISC circuit does make a small difference in the smoothness of the idle and it makes a bigger difference at low engine speeds, as when you are rolled mostly off at maintenance throttle in a turn. Throttle response coming out of that turn is much smoother. Above this speed, however, you will notice no effect whatsoever.

In addition to allowing you to set the IBS circuit, the SDS software allows you to trouble shoot most of the electronic circuits on the bike. It is worth the cost if you do your own bike work. Beyond that, I suspect it is not worth the cost. Most people will not even notice when the ISC is a little off.
 

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Discussion Starter #3
I wasn't planning on permanently replacing the ISC with an adjustable air valve, I was just thinking about using it while synching the TB's to temporarily eliminate the ISC's effect on the idle speed.

I don't want to buy a specialized tester that I might only use once or twice
 

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I wasn't planning on permanently replacing the ISC with an adjustable air valve, I was just thinking about using it while synching the TB's to temporarily eliminate the ISC's effect on the idle speed.

I don't want to buy a specialized tester that I might only use once or twice
Oh, I understood you. I didn't want to buy it, either, but I did because you can't get around the ECU.

What is the problem you're trying to resolve?
 

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Discussion Starter #5
I'm not sure what is causing the problem, it's like I have far too much compression braking.

When I'm riding at 6000 RPM and roll the throttle off and downshift from fourth into second gear to enter a series of 45 mph downhill blind corners the engine seems to idle down too far and I can't get a small amount of maintenance throttle for control.

So I have to ride along at about 30~35 mph, annoying the rednecks in their pickup trucks who don't believe in driving that slow through the blind curves.

(This road goes right through the middle of a historic 1850's ranch where freight and mail haulers would change horses and it has become the public right of way, even though the road passes between the ranch house and the barn and corral. There are driveways and stock loading ramps and corrals all along the road, but the locals never slow down.)

So far I've installed Steve's TRE and reset the TPS to transition to rich mixture at about 1450 RPM.

I also measured the difference between the front and rear secondary throttle valves and the front valve seems to be closed about 0.030"more than the rear valve.

But I will have to remove the airbox for an accurate measurement.
 

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Discussion Starter #7
Thanks, for that link, the voltage method should be easy, all I have to do is plug my voltmeter into the dealer mode connector.

I have never seen that video and I initially set my TPS using the the less accurate tachometer method as advised by another popular thread on SVRider.com.

The tachometer said that the cursor in the LCD was moving to high at 4750 RPM, so I set it to move at 1450 RPM as other SVRiders insisted.

My gas mileage drop from 50 mpg to 44 mpg and the exhaust note sounded heavy, as would be expected from an overall rich mixture.

I reset the TPS, using the tachometer method, to 2250 RPM to see what happens.

I pulled one iridium spark plug out of each cylinder.

The rear plug looked like what I would expect a plug from a four valve engine to look like,
the porcelin was white with very little color and the iridium tip wasn't melting.

The front plug, however, looked like it was *lean fouled*.

That occurs when the mixture is the cylinder is so lean the engine starts burning oil because it's not getting enough gasoline.

That plug's porcelain was a dark grey color.

Suspecting that the front fuel injector might be plugged up, I added some fuel injector cleaner to see if that helps.
 

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The voltmeter method is likely to be more accurate. Let's hope it resolves the issues you're having - please let us know.
 

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Discussion Starter #9
Today I learned that there were complaints about the idle RPM on DL1000's dropping off and the engines stalling, in traffic so Suzuki has changed the TPS sensors and the STV sensors from 13580-27G20 to 13580-27G21 in the parts list.

Suzuki used the same defective sensors on the 2007 and 2008 SV650's.

A rider on another forum said that the older TPS sensors would screw up when the engine was hot but the air was cold and the way to determine this was to spray some cooling liquid on the sensor to see if the voltage would hang up.

Another rider said that the TPS output voltage was spiking during operation, but it never caused an FI fault code.

I did the voltage mode today and saw that the TPS signalled the butterflies were closed at 1.13 volts and open at 1.17 volts, but the voltage never acted strange.

I viewed a youtube video that said I shoukd have used a box fan to keep the coolant temperature down to 190 degrees F while doing the test.

The cursor moved up by about 250 RPM when the temperature rose from 190 to 199 degrees, but the opening and closing voltage was always the same...
 

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Sooo ... assuming you reset the TPS as it should be set, what happened with your compression braking /low speed throttle issue?
 

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Discussion Starter #13 (Edited)
I read everything I could find researching this issue and built a u-tube manometer which I filled with mercury from some mercury switches given to me by the electrician at Griffith Observatory. I wanted a dead nuts accurate reading of how much vacuum the front and rear cylinders were pulling. I used mercury because it is 13.6 times as dense as water and about 27 times as dense as ATF. I did a prelimary vacuum check with the IAC still being controlled by the ECM to see if I really needed to make up a test valve set up like I was thinking about using. The rear vacuum was about 38mm higher than the front vacuum, a definite indicator that something was going on, but what, exactly?
I bought a 5/8" Raindrip irrigation valve, a 1/4" nylon vacuum T fitting and a 9/16" X1" rubber bottle stopper from Lowes hardware store. I drilled a 5/16" hole in the bottle stopper, stuck the T-fitting into that hole and jammed the rubber plug into the end of the Raindrip valve. Then I disconnected the outlet hoses from the ISC and hooked up my test rig using some plastic hoses that came with my Mity Vac to the elbows on the two throttle
bodies. I started the engine up and the front/rear vacuums were in spec. Well, duh! The ISC valve is automatically supposed to synchronise air flow into the TB's and if the TB's have never been "synchronized" since the day they left the air flow bench at the Mikuni factory, they should still be in synch. So there is something wrong with the ISC. I blew through the ISC air inlet hose while holding my finger over one ISC outlet port, then the other port. I can tell by the sound that there is more air coming through the rear cylinder outlet port and less air coming through the front outlet port. I took the ISC apart and found no damage and no evidence that the ports are clogged. I suspect that the little plastic plunger on the stepper motor's shaft may be just a bit off center, restricting air flow to the front TB inlet elbow. In the meantime, I've been riding the motorcycle with my totally reliable test set up installed and the ISC is still hooked up *electricity* and it can do whatever the ECM tells it to do.
I set the Raindrip valve halfway open (it's a half-turn valve) so the engine will idle at 1625 RPM when it's warmed up. There are no problems with cold starting, the engine idles at 1250 RPM cold, hands off the throttle. The motorcycle doesn't lurch everytime I have to go from fully closed throttle to open throttle and back and it is once again a pleasure to ride. My homebrewed Raindrip valve set up is as reliable as houses and it cost me about $10 for everything, including new vacuum hoses and a tywrap to secure it to a bracket so I can reach through the triangular hole on the frame and tweak the idle up or down if I ever need to...
 
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