Gen 2 idle issues

[Falkonworks]

I’m posting this without having 100% of the information associated with this problem. My bike has been in the shop getting worked on since January. Bike received cams and a port and polished head. New cam chain and tensioner and a few other parts I’m sure that you just do while it’s opened up. My guy got everything back together and was getting the bike ready to go on the dyno and tune, and he said it runs perfectly until it gets up to operating temp. He said once it gets warmed up the idle starts acting funny. The impression I got from him on the phone was that it’s surging. He also told me that the fans weren’t coming on. I know he had gone into the ecu and programmed the fans to come on at 185 instead of 200 or wherever they were stock. Raised limiter and etc (the normal derestricting things)... He said he took the bike down the road and he is confident with how it runs, until it gets warm. Has anyone here experienced something like this or have any input into where we should be looking? I’m just posting to see if I can get some information because the bike is 4.5 hours away from me and I can’t just get out there whenever I want. Any suggestions are greatly appreciated!

 

[Bumblebee]

I wish I had an answer...it's almost like the heat is expanding something causing more air to enter the fuel system...

I wonder if all the intake boots are tight or if one is getting out of round slightly....It sure doesn't take much to cause a surge in the idle..it has to be something really simple though. He should get it on the dyno and maybe the AFR figures will point to something...if it is ingesting more air, the AFR will spike, then from those numbers, each part of the fuel system will have to be checked systematically-airbox and all fittings, fuel system, intake boots, butterflies, etc...

 

[Hayabusa Wannabe]

When it is warmed up spray starter fluid all around the intake. More extreme changes in idle would indicate that some got sucked in through a vacuum leak.

 

[Falkonworks]

Also, I forgot to add that he said when it started surging FI was flashing. But when he tried checking the code, nothing was in there. He said he hooked it up and tried getting it to happen again but while the bike was plugged in he couldn’t duplicate the FI light even when it started surging

 

[Bumblebee]

...maybe a bad injector getting hot....???

 

[ottafish]

Considering the engines been apart, there's an endless list of "could be this"..
Sadly, I think it's going to be a process of elimination.

I discovered after lots of testing, my fans didn't turn on because the ecu was bad. It never dropped the control line to ground.

 

[Falkonworks]

Talked to him this afternoon. He said he put a completely stock flash back on it and the idle surge was gone. He said the fans still act up though, and now he thinks that is because of a temp sensor. He said they came on the first time the bike ran after being flashed back to stock. He left it for a couple hours and started it up again and then they didn’t come on...

 

[Falkonworks]

Considering the engines been apart, there's an endless list of "could be this"..
Sadly, I think it's going to be a process of elimination.

I discovered after lots of testing, my fans didn't turn on because the ecu was bad. It never dropped the control line to ground.

I hope it’s not the ecu

 

[ottafish]

Me too

 

[Hayabusa Wannabe]

Kudos to this tuner for thinking to reverse an innocuous change and identifying the unexpected problem! Nice work.

I do not know this bike at all, but know with fuel injected bikes it is typically recommended to not tune the idle or low rpm in the fuel map. I am guessing none of this applies here as the tuner would have easily reversed any such change.

Anytime I think of surging I wonder if the O2 sensor feedback circuit (or disable) is working.

 

[GIXERHP]

Compression and leak down test, as well as what is the cam timing set to? Also what cam pin is installed for the pick up?

 

[mjl3truck]

When I did the head and cams on my bike the idle was pretty ugly. I asked Greg Watters about it and he suggested that due to the big cams and cam timing there may be a problem with it running rich at idle. Hooked up the laptop and checked the AFR at idle and it was 10-11:1. went to the fuel map and watched the cells that it was idling in. Knocked some fuel out of those cells so it idled about 13.5:1, idled great then.