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[Jon]

Hi I am hoping one of you clever tuning people can answer a question for me.
Long story short, 2007 FXSTSSE fitted with Dynojet power vision with target tune.
Question
Can you confirm if the IAC warm up steps table is active all the time. The reason I ask is I thought this table was only used during warm up, but when I monitor the IAC steps on the Power Vision it appears to use the IAC warm up table continuously even when bike is up to temperature.

Hope that makes sense

Many Thanks

Jon

[IA17RGU]

Yes and no. It should have a decay, or time to stop looking at this. However....I forget what your bike has either a iac motor or it just turn the throttle plate like my 17. Either way steps are steps. So what you should be seeing is steps to let air in at idle.


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[IA17RGU]

I’ll pull my laptop back up but there are two or three iac steps. Crank run and fuel I think


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[grc]

The 2007 has an IAC stepper motor (cable operated throttle).  The ETC (electronic throttle control) bikes use the throttle plate control, those didn't come out until 2008 for Touring bikes, and much later for the other models.

Jerry

[Jon]

Hi guys
I had hoped for a definitive yes/no answer, but perhaps not to be, IA17RGU like you I thought the warm up steps would decay as engine came up to temperature, but I do not think that is what I am seeing, don't see this as a fault but rather just the way the ecu works, I believe this may only be on 2006/7 bikes as there were some changes to ecu and iac control on 2008 and later.  I did also put a call into Dynojet tech support and they were not sure either. I am hoping to set up some tests over the weekend to prove one way or the other. A bit of background why I believe the IAC warmup steps table is being used continuously even when bike is up to temp.
Bike runs great, I have one minor issue that I think I can now reproduce as required. Tickover occasionally increases to about 1200 rpm rather than its normal 1000 rpm (not a big deal but it does annoy me). When I have been cruising at about 70 mph for about 15 minutes or so pull over and tickover is at 1200 rpm, engine temp 270, iac steps 33. If I leave bike running for about 5 minutes, temp increases and iac steps drop to 30 and tickover drops to 1000 rpm and all is fine. Having discovered this is a repeatable scenario I adjusted the iac steps in the iac warmup steps table down 2 steps in the 270 degree range(from 12 down to 10). Then went out and repeated run, when I stopped tickover was 1000 rpm, engine temp 270, iac steps 31, this is what leads me to believe the iac warmup steps table is used even when bike is up to temperature. Not very scientific as many other variables could be having an influence, however I have now repeated this 4 times with the same result.  For the record I did make the idiot mistake of throwing parts at a problem without truly understanding it and replaced the iac valve - £40 wasted(I should have known better). It did not resolve the issue. This has only occurred since fitting Power Vision previously had a Power Commander 3.
I will keep you posted on progress in case this is useful to anyone else

Regards
Jon

[IA17RGU]

Sorry. Yes it is normal. This stepper motor is how your bike breathes when the throttle is closed. Perfectly fine


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[Jon]

 IA17RGU I am confused - not an unusual situation lol. Are you now saying that the iac warmup steps table is active when bike is up to temperature, I thought in your first reply you said you thought there was a decay over time.
I do understand how the iac works to control air intake at idle, but was surprised that the iac warmup steps table appears to be active when bike is up to temperature.

Thanks
Jon

[IA17RGU]

There is a decay and the warm up table will die/expire however you wanna say it. But the iac motor is still moving. Let’s say your balls deep in third gear and A cop pops up on the corner so you slam the throttle shut. The iac opens to let air by to keep the motor running. I understand your looking at the warm up table but if the iac moves...I bet they all read. I’m guessing as I have not seen your bike. As I said before mine runs off the throttle plate. I’ll change a page on my power vision and see what mine looks like tomorrow.


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[Jon]

 IA17RGU Thanks for reply, I don't think I have explained my question very well  - what I am struggling to understand is why changing the steps in the iac warm up table makes a difference when the bike is up to temperature, if it decays over time I would not expect it to have an effect when bike is up to temperature. I thought it would only effect idle speed whilst it was coming up to temperature. When I originally tried changing the iac warm up steps table I did not actually expect it to effect the idle with the bike up to temperature and was surprised when it did, you could say changing the table was a 'poke and hope' change as I could not think of anything else.

I think we are agreeing it is behaving as it should, and I am probably missing something obvious.
I do appreciate you helping with this as I hate it when something works and I don't understand why.

Thanks again
Jon

[Jon]

I think I may have got to the bottom of my misunderstanding - I found an article describing how IAC valves work. This claims many people(including me) misunderstand how the IAC warm up table works, and think the steps in the warm up table are added to the figure calculated by the ecu. It says that in fact the warm up table is used as a reference when ignition is turned on to set start/reference points for the IAC valve, all subsequent changes to IAC position are from these start/reference points either up or down. That does make sense to me and would explain why it appears to me that the iac warm up table is always active although it is in fact only actually used at startup. How true this is I don't know but I have no reason to disbelieve it, and it does explain what I have seen in my tests.

I think I am going to claim a success on my fix as it is working for me, and put this post to bed

Thanks for replies and help
Regards
Jon