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Discussion Starter #1
Anyone know if this is normal? My butterfly valves in the airbox appear to be stuck open. I imagine something is wrong since there is no point to a valve that is just open all the time...here is the vid.

 

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So I did some research which I guess I should have done before making this thread but I had no idea what these valves were called so wasn't sure what to even look for. They are the secondary throttle valves and controlled by the secondary throttle valve actuator (STVA). From what I can gather looking online, my actuator is actually working fine since it can pull the valves through the full range of motion and also explains why it isn't throwing a code. I guess I'll research how to fix this - if I can't - I'll just remove the whole thing since it makes no difference. They have been stuck open since I got the bike and I have no qualms about the performance. It also explains why it idles high initially which is something I've been wondering
 

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Alright, made some progress tonight although I am a bit puzzled. Pulled the airbox and used a muiltimeter to check the resistance as instructed in the service manual.

However, my multimeter is showing an insane reading of 208 with the key off and -0.8 with the key on. I am not sure how to interpret these but I'll pick up a torx set tomorrow and play around with the adjustment screw a bit.
 

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From what I can gather looking online, my actuator is actually working fine since it can pull the valves through the full range of motion and also explains why it isn't throwing a code.
I dont see it moving the valves through any range of motion.
I'd suspect STVA motor gears stripped. That or the secondaries have been dissembled and resembled incorrectly.
 

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+1 on stripped gears. TheGeek might have the parts to repair it. There are threads here as well as this about how to take it apart to check. A less likely possibility is that the sensor is bad. Your measurements don't make any sense. Are they volts or ohms or what? What year?

Suzuki claims that the secondary throttle valve improves the throttle response.
 

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Dreaming of buttsecks for years...
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It's doing what it's supposed to do. They are supposed to be open during prestart. Do another video, but start the engine and let it run for 30 seconds and then they'll close.
 

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+1 on stripped gears. TheGeek might have the parts to repair it. There are threads here as well as this about how to take it apart to check. A less likely possibility is that the sensor is bad. Your measurements don't make any sense. Are they volts or ohms or what? What year?

Suzuki claims that the secondary throttle valve improves the throttle response.
The readings make sense because he's measuring the resistance of the ECU too...
 

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Discussion Starter #10
It's doing what it's supposed to do. They are supposed to be open during prestart. Do another video, but start the engine and let it run for 30 seconds and then they'll close.
Thanks, I didn't know that. I actually can't start the bike right now because it's inside my office in a commercial building more or less winterized. I am sure I will set off some kind of alarm if I turn this monster on.

You are right, I was measuring the resistance of the ECU, not the actual sensor, which I measured at 0.58 which is slightly out of calibration. My issue now is I can't seem to adjust this damn sensor to get below 0.54. (I need to get it to 0.48-0.51)

There seems to be some threshold of movement where if I go below 0.54, something messes up and the reading just jumps to 500. This threshold is razor tight too so I wasn't even able to get the 0.54, but with some luck I'll be able to. The issue is how can I get into proper spec at 0.48-0.51
 

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Thanks, I didn't know that. I actually can't start the bike right now because it's inside my office in a commercial building more or less winterized. I am sure I will set off some kind of alarm if I turn this monster on.

You are right, I was measuring the resistance of the ECU, not the actual sensor, which I measured at 0.58 which is slightly out of calibration. My issue now is I can't seem to adjust this damn sensor to get below 0.54. (I need to get it to 0.48-0.51)

There seems to be some threshold of movement where if I go below 0.54, something messes up and the reading just jumps to 500. This threshold is razor tight too so I wasn't even able to get the 0.54, but with some luck I'll be able to. The issue is how can I get into proper spec at 0.48-0.51
It would help if I paid attention to what bike we're talking about......
 

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Discussion Starter #13
The manual's resistance value is wrong. Unplug the sensor and adjust it to 1.5k ohms across the outside 2 pins for fully closed.
Sorry but I am a bit of a noob when it comes to this stuff - what does that mean exactly? Currently the only thing I can get out of the sensor is the voltage ranging from either 0.54 (lowest I can go when closed) or a max of 4.5ish when it's wide open.
 

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"proper spec at 0.48-0.51"

Where are you getting that spec? Everywhere that I look it's 0.48 - 0.52 V.

The readings still don't make sense to me. He was initially reporting "208 with the key off and -0.8 with the key on". The 208 value could have been a resistance but I know of no way to get a negative resistance. Later he says "if I go below 0.54, something messes up and the reading just jumps to 500". It sounds like he's measuring voltage at first but it somehow jumps to resistance (or is that 500 V?). OP - Is your multimeter working OK and do you know how to use it? These readings and your apparent refusal to list measurement units has me wondering.

"The manual's resistance value is wrong. Unplug the sensor and adjust it to 1.5k ohms"
There are specs in the service manual for the TP sensor resistance but I can't find any for the STP. Where is a resistance spec listed?

The secondary throttle seems to chatter, both visibly and by sound, when it reaches full open in the video. I don't recall that on my K6, which is why I'm suspicious. Perhaps it's associated with a misadjusted sensor.
 

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Sorry, rough morning. I lost focus on which forum I was in. Now that my head is back on straight, I realize in the 1000 forum.

OP, what year is your bike?
 

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The secondary throttle seems to chatter, both visibly and by sound, when it reaches full open in the video. I don't recall that on my K6, which is why I'm suspicious. Perhaps it's associated with a misadjusted sensor.
For them to bounce off the upper limit is pretty normal. No two sensors are alike, so for them to have exacting open and closed readings just isn't possible. They make the program have one hard value, which is the closed value. Then the bike reads the upper limit as part of the startup sequence and then it knows the full range. Nothing unusual about it.
 

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Discussion Starter #18
"proper spec at 0.48-0.51"

Where are you getting that spec? Everywhere that I look it's 0.48 - 0.52 V.

The readings still don't make sense to me. He was initially reporting "208 with the key off and -0.8 with the key on". The 208 value could have been a resistance but I know of no way to get a negative resistance. Later he says "if I go below 0.54, something messes up and the reading just jumps to 500". It sounds like he's measuring voltage at first but it somehow jumps to resistance (or is that 500 V?). OP - Is your multimeter working OK and do you know how to use it? These readings and your apparent refusal to list measurement units has me wondering.

"The manual's resistance value is wrong. Unplug the sensor and adjust it to 1.5k ohms"
There are specs in the service manual for the TP sensor resistance but I can't find any for the STP. Where is a resistance spec listed?

The secondary throttle seems to chatter, both visibly and by sound, when it reaches full open in the video. I don't recall that on my K6, which is why I'm suspicious. Perhaps it's associated with a misadjusted sensor.
Yeah, I am not too familiar with electronics nor my multimeter (Fluke), but the 0.48-.51v figure is just what I have gathered from browsing various old forum posts online and remnants of various service manuals. STP information is not too well documented from what I can see, either that or Google's search just confuses it with TPS which makes filtering the search results more difficult.

I am measuring the voltage. When it gets below 0.54, it seems to jump to a 3 place digit which makes me wonder if my multimeter is automatically just displaying millivolts to me instead, although 0.54 seems like a weird cut off point

Sorry, rough morning. I lost focus on which forum I was in. Now that my head is back on straight, I realize in the 1000 forum.

OP, what year is your bike?
It's a 2003 GSXR 1000.

Like I said, the bike isn't throwing any codes at all and this literally poses no noticeable issue other than the annoying chattering during start-up which I suspect isn't normal. It's winterized currently and I got some free time so I am taking the time to do this the right way and also learn from it hopefully.
 

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A Fluke multimeter ought to be fine. I use a Fluke 8060A that's around 30 years old and it's still plugging away. Features vary from model to model but I'd suggest that you look for a setting where it isn't auto-ranging, if it's there. Auto-ranging is just going to be a source of confusion if you're new to or don't regularly use the meter.

The full K3/K4 service manual is downloadable and is a better source of information than online posts. STVA related information is on pages 4-45 to 4-49 and 5-22. The manual isn't perfect though. On 5-22 the sensor adjustment procedure is described, which involves adjusting the sensor while measuring the output voltage. But it leads off by saying "measure the sensor resistance" and later says to set the meter to resistance (irk!). Possibly the original procedure involved measuring resistance and it was later changed to voltage but not properly updated. I've spent a lot of time rooting things like that out of the K5/K6 manual.

TheGeek: I now see that the STP sensor resistance is listed as 0.5 kΩ closed / 3.9 kΩ open in the K3/K4 and K5/K6 manuals. The sensor resistance isn't mentioned at all in the K7/K8 or K9-L1 manuals. Are you saying that the 0.5 kΩ value is in error and should be 1.5 kΩ? I also see that the K7/K8 manual lists the sensor voltage as 0.5 V closed / 3.9 V open. Strangely similar.
 

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Discussion Starter #20
A Fluke multimeter ought to be fine. I use a Fluke 8060A that's around 30 years old and it's still plugging away. Features vary from model to model but I'd suggest that you look for a setting where it isn't auto-ranging, if it's there. Auto-ranging is just going to be a source of confusion if you're new to or don't regularly use the meter.

The full K3/K4 service manual is downloadable and is a better source of information than online posts. STVA related information is on pages 4-45 to 4-49 and 5-22. The manual isn't perfect though. On 5-22 the sensor adjustment procedure is described, which involves adjusting the sensor while measuring the output voltage. But it leads off by saying "measure the sensor resistance" and later says to set the meter to resistance (irk!). Possibly the original procedure involved measuring resistance and it was later changed to voltage but not properly updated. I've spent a lot of time rooting things like that out of the K5/K6 manual.

TheGeek: I now see that the STP sensor resistance is listed as 0.5 kΩ closed / 3.9 kΩ open in the K3/K4 and K5/K6 manuals. The sensor resistance isn't mentioned at all in the K7/K8 or K9-L1 manuals. Are you saying that the 0.5 kΩ value is in error and should be 1.5 kΩ? I also see that the K7/K8 manual lists the sensor voltage as 0.5 V closed / 3.9 V open. Strangely similar.
Yeah, the manual I found didn't say much other than this tidbit

"The sensor should produce following voltage. position sensor 0.15 V sensor voltage < 4.85 V C29 Without the above value, C29 is indicated." and this:

Secondary throttle valve is closed : Approx. 0.5 kO
Secondary throttle valve is opened: Approx. 3.9 kO

Which I assume is referring to voltage.

So based on this, I should just calibrate the sensor to 0.5 when closed and call it a day.

I also found this random document online which says the same thing:

http://www.bugmanweb.com/gsxr/gsxrimages/adjustments/stpsadjust.gif

And thanks for the tip regarding the auto-range, yeah I think that is what it might be doing. Definitely confusing.
 
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