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Yes, STVA/ stepping motor, and yes again I meant to say secondary throttle plates flutter back and forth. I saw a post by Chuckster saying that he saw hundreds of ECU's fail on 06/07 models, so even thou I never had charging issues I decided to check my voltage regulator. It passed the inspection as per Suzuki shop manual, however it has to small holes in the back of it. Possibly its on its way out and it damage my ECU
I know Chuckster has previously mentioned failures of these ECMs. Hopefully he will describe the failure mode. I have not read about a lot of failures in the last couple of years except for ignored over volt condition and one guy who's friend started disconnecting battery wires while the bike was running.

If you are getting 14.0-15.5 volts measured at the battery at 5k rpm then the charging system is good and not the cause.

It seems when the bikes overvolt they go to about 18 volts, blow headlight bulbs and boil the battery. When the battery boils out it really spikes, the ECM fails and the bike stops. This does not seem to be the scenario you describe.
 

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You are right, that is why I'm confused here. My bike still has original battery in it as I always plug my battery tender when not in use, just a habit. However after hours of testing and searching forums I decided to pull my regulator off and inspect it. Like I said it passed, all I found was two little marks at the back, size of a small screw/head. Just in case I ordered a new one from motorcycle superstore. ( Ricks)
The bike runs/starts fine, except for the C28 and secondary plates fluttering.
 

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Discussion Starter #64
Has to be a 2006 or 2007 ECU. There's really no way to diagnose it other than swapping it with a known good. It's more of a process of elimination to get to that point, which you've already done. It's just a hypothesis and I really don't know the pathology, how much of an over-volt it takes to cause the damager, or any other details. Only a lot of history and testing to show the STVA is good, and reports that the bike just suffered from other electrical issues. Just a lot of reasons to think the ECU is the issue.

The other issue I've seen is a STPS that has cross faulted. Usually that causes a different behavior that a fluttering. I would say your ECU is the faulty component.
 

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Thanks Chuckster, I tried a known STPS today and it made no difference. At this point I'm looking for a used ECU, however so far no luck. Will post as soon as I fix the problem.
 

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As promised here is an update. In my case the ECU was the problem. I installed a used one and the problem went away. I also got a Ricks R/R just to be sure cause I still can't understand what caused the ECU to fail. Here is a little fact:
Suzuki R/R output at idle 14.4V, 5K RPM 15.48V.
Rick's R/R output at idle 14.45V, 5K RPM still 14.45V. Those are the values I took from my bike and Rick's R/R works much better. It is very possible that O.E R/R when very hot at high RPM spikes the voltage past 15.5V. I'm thinking of adding a "volt gauge " to the bike in the near future.
Thanks for all your input and help.
 

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As promised here is an update. In my case the ECU was the problem. I installed a used one and the problem went away. I also got a Ricks R/R just to be sure cause I still can't understand what caused the ECU to fail. Here is a little fact:
Suzuki R/R output at idle 14.4V, 5K RPM 15.48V.
Rick's R/R output at idle 14.45V, 5K RPM still 14.45V. Those are the values I took from my bike and Rick's R/R works much better. It is very possible that O.E R/R when very hot at high RPM spikes the voltage past 15.5V. I'm thinking of adding a "volt gauge " to the bike in the near future.
Thanks for all your input and help.
Glad you got it fixed and thanks for posting the resolution.

Are you sure it was an OEM R/R you had on it previously?

There was another guy that had an Ebay/Chinese R/R that also controlled well when cool but overvolted when it got hot.

I have not read about an OEM unit doing this is why I ask.

Do a search for voltage gauges, there are a couple of neat digital models and annunciator lights.
 

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Has to be a 2006 or 2007 ECU. There's really no way to diagnose it other than swapping it with a known good. It's more of a process of elimination to get to that point, which you've already done. It's just a hypothesis and I really don't know the pathology, how much of an over-volt it takes to cause the damager, or any other details. Only a lot of history and testing to show the STVA is good, and reports that the bike just suffered from other electrical issues. Just a lot of reasons to think the ECU is the issue.

The other issue I've seen is a STPS that has cross faulted. Usually that causes a different behavior that a fluttering. I would say your ECU is the faulty component.
Same problem as mentioned above. STVA checks out good abot 7.4ohms then checked the stps also good readings open and closed butterflies. What I'm wondering is if it's possible to use an ecu from an 09 an long as you get the wiring harness for that year also? Because the ecu for 06-07 gsxr 750 seems to be hard to come by.
 

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Discussion Starter #69
There's a reason they're hard to come by.....

I don't know if the 09 would be compatible with the 06/07, but without some concrete confirmation, I wouldn't even try it. Just one pin different and you could risk bricking the thing.
 

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issue after c28

I need alot of help here guys. i had a c28 code pop up on my bike and i am mechanically inclined enough to do the repair myself which is did. 7.2 ohms on both of my connectors and the butterflies now when i turn on the bike go all the way open and rattle a bit but after all of that i get a c14 code which i know is the tps on the stva. i go to adjust it and the line will never go middle even with 1000ths of an inch difference its top line or bottom only. At one point of time when i was troubleshooting the stva i did get the line to go middle once. I tested the voltages coming out of the ecu and it reads 5.0 VDC on the red wire and 4.42 on the other wiring. When i turn on the bike the code pops up and it seems that when it is trying to regulate where it should be at it gets stuck in the middle of moving the secondary valves and the code wont clear. What am i doing wrong with adjusting it? I have bought a new tps thinking mine was bad and that failed.
 

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ive done some more troubleshooting. What i have found is i have 7.2 ohms all the way to the plug that goes to my ECM. Im assuming my only option is that my ECM is bad and i need to get a new one.
 

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Discussion Starter #72 (Edited)
C14 is the TPS UNDER the STVA. The one mounted to the STVA is the STPS. Most likely, you installed your STVA wrong, and unless you're lucky, you've damage the STPS. C14 is completely unrelated to the secondary system. Are you sure you're mechanically inclined???

The STPS can not be adjusted by the line. That's only for the TPS. The STPS has to be calibrated directly. Your ECU isn't faulty, you're just making mistakes.
 

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well, you are right what i was reading out of the manual was totally my fault. I did fix the STVA, and its giving me good multimeter readings, and it is working fine by opening up when i turn on the bike. But after it runs for about 15 secs the throttle vavles go closed and stay closed then a c28 pops up again. i tested the resistance to the wires and everything all the back to the ecu and its all 7.2 ohms. So you say it isnt an ECU at that issue? I am closing the vavles and installing the STVA and that is what is happening. Any advice to me to get this running?
 

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Discussion Starter #74
I'd be real surprised if it was the ECU. More common is a false positive test. I'd say send it to a pro.
 

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Continued Troubleshoot

To this point of it all ive got the motorcycle popping out a C28 code 15 secs or so after it is running. The butterflies open fully then close fully then a C28 pops up. Is this the STPS not set properly? or is this the STVA is still not working properly? Or a faulty STPS? It will run if i set the valves open a little bit and i cant get past 6k Rpm's if i dont open then a little it will die. Please help.
 

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Discussion Starter #76
If they move open, then back closed at powerup, the STVA is usually fine and it's a sensor issue. Pretty easy test. Connect a meter to the sensor in the positions of the black and red wires. Cycle the secondaries. Regardless of position, the reading shouldn't change. If it does, your sensor is faulty.
 

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Thanks for the help chuck, the reading i get is 4.8k ohms no matter the position. If i read correctly somewhere you said it needed to be at 1.6k ohms? if i put the sensor on in the closed position i get a c28 if i put them on with the valves open i get a c14. Definite bad sensor?
 

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Hey guys. Im new to this site and Im looking for a bit of information. Ive read a lot about the testing of the stva but I cant seem to come up with a fix for my issue. Im on an 08 600 and while racing the other weekend I noticed that an injector was hung open. I happened to have a spare throttle body assembly with me so I just swapped it out and put the original stva on the new assembly. I couldn't get the stva to sync correctly. I noticed with the original setup the butterflies were closed with ignition off. When I turned the ignition on they would fully open then close again. After the swap they open probably 1/16th of the way and close back and makes a humming/buzzing sound. I pulled it back off. Opened the stva(turned completely ccw) and opened the butterflies, reinstalled and cycled the key. It completely closed, opened the 1/16th then closed and more humming. Obviously, Im missing something somewhere. Help, please?
 

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Discussion Starter #79
Sounds like a sensor alignment issue. Was it a complete throttle body or did you swap over your working STVA?
 

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Afternoon, master in c28s of thine GSXRs. I'm also getting the C28 code on my 07 Gsxr 600 that I recently purchased with only 1000 miles. The previous owner did lay it down maybe going 5-10 MPH very low speed minimal damage. First i wasn't able to find the testing instructions for k7s on your website maybe i'm just blind since the zip just doesnt work for me. Just some background with the issue, I have disabled the exhaust Set Valve by pulling plug 34 from the pin while in the wide open position I did see some improvement as far as the issue of it not wanting to accelerate at a normal speed above about 6k RPM but now it's moved closer to 8k rpm only in gears 2-6 and will even lose acceleration momentarily and slow down but with no issues in first gear getting well over 10k rpm without issue. I recall you reading that it is most likely the ECU gone bad or could it still be the STVA? I'd like to test it but unfortunately can't open the damn zip folder.
 
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