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Discussion Starter #1
Refer to this thread for more info http://www.gixxer.com/forums/showthread.php?t=351623

Have a K8 ex Superstock race bike that I have put back on the road but have been having some cooling & idling issues with it since day one. Dont have much history ont he bike so can't answer any questions there. I have never seen a stock K7/8 start up & idle so have no reference point to base any of my current observations on except to compare them against my stock K6.

Can anyone tell me how the bike should behave normally in a stock setting with the ISC valve? I have reset the idle speed manually to about 1300RPM hot & it seems to run well there. The engine doesnt rev higher during start up like my K6 does & the STV's are also not fitted to my K8 if that makes any difference.

Can the ISC be removed & plugged up & would that be something race tuners would normally do>


Cheers,

Kenny
 

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The ISC is a bleed air valve that allows additional air around the throttle plate to maintain steady state idle under all conditions including warmup. It's preety old technology, actually, having been around for decades and used on many EFI applications. If the idle is rising there are so many reasons why this might be happening that don't involve the ISC that you can't nail the problem to that.

Don't know what ECU, don't know what map, don't know what engine specs, etc. etc.

ISC failure typically allow a VERY fast idle, 4000 rpm or so and this is the issue Suzi recalled to fix.
 

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I have reset the idle speed manually to about 1300RPM hot
I have limited knowledge of the ISC system but was under the impression that there wasn't any manual adjustment and that it could only be done electronically via SDS, etc. Can you expand on what you're doing?
 

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Have you read the service manual Kenny?

There is a procedure for setting the ISC. You will need the Suzuki tool to do it. May be worth taking it to a big Suzuki dealer that has the SDS tool.
 

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Discussion Starter #5
Havent read the manual yet! Also am wondering if engine tuners actually remove & plug up the ISC or leave it alone... Dont know if this ECU has been flashed either (doubtful though due to the years the bike was used). Am wonder also why the bike doesnt run at higher RPM when i start up initially & then settle back to normal idel speed like my K6 does.

When I got the bike the engine would start at about 1200 RPM & then the idle speed would creep up to 1700 RPM when fully warm. last wee I adjusted the idle stop strew (clutch side of throttle bodies under tank) so the engine runs at about 1300RPM hot but it still starts at 1200RPM (& off the 1st turnover too - nice).

If the ISC bleeds air in to raise control the idle speed I would surmise that the idle stop would have to be set lower than 1150 RPM (stock K7/8 ECU idle speed) so that the ISC can actually be capable of bleeding air in to control the idle speed. Setting the idle artificially higher means the ISC will be permanently shut as it's trying to lower the RPM back to 1150RPm right??

I didnt set the RPM lower than 1300 as the bike was hunting slightly lower than that. Reckon its just lack of use (was barely used for 2 years) & the injectors need a bit of running to get them flowing good again. Will run some injector cleaner (Have that Caltex Techron stuff to try) too. Other than that I can check the throttle body synchronisation also.

The idle has been very stable the last few days so maybe I'll try lowering the throttle stop position 200RPM & see what happens??
 

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I couldn't see anything in the K8 service manual about high idle setting for cold start.

The K6 SDTVs control the high idle on start up by opening the SDTVs fully and the cam on the SDTV shaft throttle pulley side pushing the fast idle mechanism.

K8 TB doesn't have this mechanism.

This one is at 24°C and doesn't high idle
 

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If you go through the K7 service manual, the only places where fast idle is mentioned are two places that are just carryovers from the K6 manual. Per 10-55, the fast idle RPM has been removed from the specifications. The sample SDS check on 2-34 doesn't show a fast idle like before. I conclude that it's gone.

The guy in the video is an idiot. Within 6 seconds of starting a cold engine, he has it over 11,000 RPM.
 

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For what it's worth, my 2c since that is what you originally asked.

My K7 has never idled higher than the normal 1150 odd rpm, no matter the temperature. That includes cold mornings with air temperatures of 1-3 deg C.

And as per Bill's comment I have not seen much mention of it in the FSM. There is no need for the high idle since the bike starts and idles very easily no matter the temperature. This can be expected since this is the same method for idle control used by most modern cars and they also do not have "high idle" modes anymore to simulate a choke's operation.
 

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Hey guys, Kenny was asking about the K8. Even though the K7 is virtually the same. Yes, the SDS graphs give a clue also but not conclusive IIRC,

The relevant part of that video was that it was brand new and presumably stock, there was no high idle when it was stone cold sober and it was a K8 not a K7. So Kenny, you can sleep easy on that one that your bike is behaving normally.

BTW, you owe me when I have some questions on AC. Don't leave the country, all right!
 

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And different part numbers for the ECU or ECM and not the exact same software IIRC, correct me if I am wrong on the SW.
 

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From this thread:
http://www.gixxer.com/forums/showthread.php?p=4934679#post4934679

Found this posted by RidgeRacer on this site:

The ECUs are physically the same. The Part numbers are.

32920-21H00 K7 EU
32920-21H10 K7 US
32920-21H50 K8 EU
32920-21H60 K8 US

Both the US and EU have anti-theft that will immobilize the bike but they are different. The "immobilizer" on the EU version has a little antenna around the lock that broadcasts an Radio Frequency (RF) signal. The keys have little RF identification (RFID) chips in them that broadcast their unique number when they detect the query from the ECU. The number in the key needs to match the number in the ECU or the bike won't start.

The US bikes have a resistor in the ignition lock that makes the voltage on one of the power wires coming out of the lock to the ECU a fraction of the battery voltage. The ECU measures this voltage and if the ratio is not correct the bike will not start.

So if you use an EU ECU you will need an RFID lock/harness and the matching key. If you you use the US ECU you will need the lock with the resistor in it. However by wiring the resistor into the harness you could get a US ECU to work on an EU harness.

For what it is worth the only difference between the two ECUs software some of the Secondary throttle and Exhaust servo maps are slightly different.
I stand corrected. But nothing to do with the ISC, either.
 
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