K7 fast idle on cold start isn't working- should I adjust the STP sensor? - Suzuki SV650 Forum: SV650, SV1000, Gladius Forums

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Old 05-08-2016, 09:53 AM   #1
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K7 fast idle on cold start isn't working- should I adjust the STP sensor?

I noticed lately that my bike isn't starting well in the cold (e.g. after it's sat overnight in 40-50 degree or colder weather) and am trying to figure out what the cause of it is. On a cold start on a cold/chilly morning, the bike turns over once or twice before firing, but the weird part is that it tries to go directly to the standard idle I have it set at of ~1300rpm's. It doesn't try and idle faster for a bit to try and warm the engine up, which makes me think that something is off with the fast idle (as I understand it, on K7's like mine and later, the fast idle is not controlled by a cam like on older models but by the STP sensor?). The end result is that the bike still starts up OK, but it feels like it kind of lags or is struggling for 10 or so seconds as the engine warms up and the rpm's slowly increase from about 1100 to 1300.

I have confirmed by opening up the airbox that when the ignition is turned on, the STV's rotate and go through their cycle normally, so I don't think it's a case of them being stuck. What I did notice through a cold start test that I ran this morning (with the airbox open) is that the STV's didn't open up at all when I hit the ignition button. I found this somewhat worrisome because my understanding is that on a cold start, the STV's are supposed to open up fully to allow the bike to fast idle. That said, this morning (when it's a bit warmer, about 59 degrees), the bike fired right up and went into a steady idle without any issues, so I'm thinking maybe it's just that the temperature wasn't cold enough to cause the brief stumbling issue I described above, or to trigger the fast idle which would open up the STV's.

Before I spend the money on a multimeter to do the STP sensor adjustment described in the service manual for K7+, is there anything else I should be looking at/considering?

For additional context, my battery is only a year old, and it turns the bike over fine so I'm pretty sure it's not that. I also just changed spark plugs so I have ruled those two out as the cause for the cold start issue, which isn't a serious one, but I'd like to get it sorted out if possible as I do ride until it gets to about 25 degrees F.
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Old 05-08-2016, 10:36 AM   #2
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Re: K7 fast idle on cold start isn't working- should I adjust the STP sensor?

Is the bike kept parked outside in the cold or in a warmer location that you roll it out into the cold before you start it ?

I have issue with my V-strom, without a manual enrichment, while it starts quickly,, will not idle on it's own because the water temp is 20-30 or more warmer air intake temp, so the ECU thinks it is warm enuf to idle without enrichment

when I leave it out in cold, it starts and idles up as expected



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Old 05-08-2016, 11:02 AM   #3
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Re: K7 fast idle on cold start isn't working- should I adjust the STP sensor?

I street park it unfortunately so it's exposed to some cold temps- I don't have a garage (yet).
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Old 05-08-2016, 04:48 PM   #4
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Re: K7 fast idle on cold start isn't working- should I adjust the STP sensor?

You mentioned you have the idle set at @ 1300 rpm. On the 07 the idle speed is non adjustable. If you actually made an adjustment to something you thought was the idle speed, but was really something else, that may be the issue.
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Old 05-09-2016, 08:45 AM   #5
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Re: K7 fast idle on cold start isn't working- should I adjust the STP sensor?

Quote:
Originally Posted by locoblanco View Post
You mentioned you have the idle set at @ 1300 rpm. On the 07 the idle speed is non adjustable. If you actually made an adjustment to something you thought was the idle speed, but was really something else, that may be the issue.
Ah, correction- I meant my idle sits at 1300 and I set the TPS to begin injecting fuel just above that at about 1400. From what I saw when I was setting the TPS sensor, I could get the idle out whack/have it run high, like 2k if I got it far off.

A part of me is thinking that it may actually just be my Antigravity battery struggling to wake up from the cold- I'm going to try leaving the headlights on for a bit tomorrow morning to warm it up the battery and see if it changes the way the bike starts.
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