[Alex1704]

Hello guys,
I have a 2008 gsxr 600 and I have an issue with the idle. It stays only at 1000 rpm and it dies if I don’t speed up when i leave and also is sputtering . After 4k rpm the bike runs good, no problem. I don’t know if there is a conection with that but when the engine is hot and I refuel the bike will start like normal (all the time) . Sometimes is working good when is hot, but only sometimes.until now I changed the spark plugs, fuel pump with the filter, adjust the TPS sensor, I bought a PC with the hope that it might work, changed the ISC valve (if I loosen the 2 screws that hold the isc valve and pull the valve a little bit out while is running the idle is increasing) so I think is something with the air-fuel ratio mixture . I also checked the primary injectors. They have a good spray pattern. I will try to attach a video so you can see.
I checked the vacuum hoses also and tried to start with the IAP sensor unplugged with no luck.
Any thoughts?? Please help
Thank you

2008 gsxr bad idling

youtube.com

Attached a video with the problem

 

[rv6john]

Welcome to the forum.

Check that all cylinders are firing when at idle by checking each header with a spray of water.

I was trying to hear in your video of it sounded like all cylinders were firing but you kept blipping it so that didn't work.

The other thing is that the idle speed needs to be set with the Suzuki diagnostic tool or equivalent. I'm sure changing the ICS did not help this.

 

[Alex1704]

Hi. Thanks for reply.
i checked the the exhaust for each cylinder and they are all hot immediately after I start the engine. And for the ISC valve I bought the healtech tool and I reset the valve with no succes.

 

[rv6john]

Just listening to the video again, it does sound to me that one cylinder is not firing correctly.

I was hoping you could pin it down with the header check.

Just watched and listened again and I believe the low rpm (1k) is due to a cylinder going off line at idle.

You an also use a an infrared heat detector gun and I've also used WD40. WD40 will flash off a running header but usually just smoke on a cooler one.

 

[Alex1704]

Ok. So your saying that i need to start the engine and put some WD-40 on the exhaust pipes and one cylinder if it has problems is gonna smoke and flash off. Ok, I will try this today. Thank you

 

[rv6john]

Ok. So your saying that i need to start the engine and put some WD-40 on the exhaust pipes and one cylinder if it has problems is gonna smoke and flash off. Ok, I will try this today. Thank you

No, the running, hot cylinders will flash off the WD-40. If the cylinder is cooler, it will just smoke and dribble.

Just try it, any difference will be obvious. I do this about a minute after starting the engine, the exhaust is hot enough by then to give results.

 

[Alex1704]

I’m back. I tried with the spray and it seems that they are all at the same temperature.tomorrow I will try with an infrared thermometer. What to check next? Any ideas. Thanks

 

[XPOH]

I’m back. I tried with the spray and it seems that they are all at the same temperature.tomorrow I will try with an infrared thermometer. What to check next? Any ideas. Thanks

Did you synchronization of throttles procedure? I don't know is it actually for 2008 model, but on 2006-2007 it is very important to do for good idle.

 

[Alex1704]

Hi guys. I tried with the infrared thermometer and my 1st cylinder is colder with approx 30-40degrees celsius. I tried to Swap the coils 1 with 4 and Still the same, So the coils are not the problem. I checked the coils plug caps with the multimeter and all of them are around 5-6v when crancking. Could be the CKP sensor ? What do you think?

 

[rv6john]

30-40 degrees is not a huge difference.

I would check the throttle body sync first.

 

[Spyder13]

but 30-40 degrees CELCIUS is a big difference. If you really meant Celsius, I would check that you are actually getting good spark with the plug in that cylinder. Then I would sync the throttle bodies according to the procedure in the manual. Last would be to test the injectors. You could have one hanging open, and flooding that cylinder. My money is on the throttle body sync.

 

[Alex1704]

So if the throttle body is not sync Could cause such a rough idle?

 

[rv6john]

@Spyder13 Good catch! I did not see the Celsius.

@Alex1704 yes, especially at idle where the amount of air metered is so small.

 

[Alex1704]

Hi again. So , i tried to make the throttle body sync but now is worse than before, it doesn’t want to idle . If I’m not keeping the throttle is dying. I just orderd the CKP sensor . I hope is that one

 

[rv6john]

Hi again. So , i tried to make the throttle body sync but now is worse than before, it doesn’t want to idle . If I’m not keeping the throttle is dying. I just orderd the CKP sensor . I hope is that one

What happens if you hold the throttle open a bit? Does it run well? Sound good?

I'm not sure why you are replacing the CKP.

 

[Alex1704]

Is running like crap. Very rough. I think that if the CKP sensor is bad it doesnt send the right signals to the Ecu and maybe that’s why I have a rough idle .

 

[rv6john]

I think you are just throwing parts at it now, hoping something will fix it. I can't see why a bad CKP would cause your issue.

So back to my question. It runs like crap with the throttle held opened to 2, 3 or 4k rpm?

 

[Alex1704]

Yes

 

[XPOH]

After 4k rpm the bike runs good, no problem.

t runs like crap with the throttle held opened to 2, 3 or 4k rpm?

Yes

Where is hidden a white dog? 🤨

 

[rv6john]

If it runs like crap at higher power and you still have the big exhaust header temperature difference you have a problem with one cylinder (the colder one probably).

Swap that spark coil with another and see if the problem travels. If it doesn't I'd do a compression check to confirm the engine is mechanically sound then move on to the injector.