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Buell Forum » Old School Buell » Archive through September 01, 2017 » S3 DDFI Idle surge when hot « Previous Next »

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Williamscottrobertson
Posted on Thursday, July 20, 2017 - 10:40 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

So my S3 started this Idle surge. Granted it's been 95+ degrees the past few weeks here in GA. Come off of a ride or at a red light, it'll Idle fine for about a minute or so. Then, I was waiting for a train to pass, and this surging began, like someone flipped a switch. I was thinking maybe an ETS but I don't want to throw parts at it. It also has a little hesitation at about 2500-3k rpm with a throttle roll on.

2000 S3, 4,800 miles, stock intake, V&H pipe, "race" map on ecm. Replaced the cam sensor and re-timed a couple weeks ago. No surging before the cam sensor change but hard starts were common.

YouTube video of the surging after a ride the other night, sorry it's in the dark.

https://youtu.be/ICOvEBQmeBA
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Hootowl
Posted on Thursday, July 20, 2017 - 01:31 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Turn your idle down a smidgen.
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Natexlh1000
Posted on Thursday, July 20, 2017 - 03:43 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

+1 on the idle reduction.
I set mine to 950 when hot.
Cold starts, I have to hold the throttle a tiny bit til it's warm but that's it.

Plastic bodywork doesn't rattle in traffic like it used to also.
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Buelliedan
Posted on Thursday, July 20, 2017 - 04:54 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

when's the last time you replaced the intake seals? If you never have it is a good idea to change them every 3 years or so as they do go bad.

The surging idle is often caused by leaking seals.
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Ocbueller
Posted on Thursday, July 20, 2017 - 05:57 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Injected tube frame Buells go into skip spark mode when hot in order to help cooling with excess unburned fuel. Probably what you are experiencing.
SteveH
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Two_seasons
Posted on Thursday, July 20, 2017 - 06:15 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

+1 on skip spark. Normal in hot weather. Turn off bike while waiting for trains.

There are lots of trains in GA
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Williamscottrobertson
Posted on Thursday, July 20, 2017 - 06:22 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

That's what I was thinking was maybe skip spark but didn't seem as abrupt as I thought it would be in that mode. The intake seals are original, I did the old brake cleaner test and it checked good, no changes in in the Idle.

I'll Idle it down some, I think the book called for 1050 rpm hot after I did the race map and zeroed the TPS.

Thanks for the input.
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Hootowl
Posted on Friday, July 21, 2017 - 09:36 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

1050 is what the manual calls for. I ignore that and set mine at 950. Less vibration. Comes back to idle better. Stable idle.
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Natexlh1000
Posted on Friday, July 21, 2017 - 12:12 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Yeah it idles in traffic much more cool too.
Don't try for the "cool guy with the Harley" idle though.
The flywheels are lighter and the alternator won't be able to keep up with the injection and other crap.

950 for mine at least is a sweet spot.
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Williamscottrobertson
Posted on Saturday, July 22, 2017 - 09:06 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Rode today, 95 degrees this afternoon. Idle dialed back to 950. Definite improvement. No more surge, just the potato gallop. Thanks for the suggestions!
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Hootowl
Posted on Saturday, July 22, 2017 - 09:48 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

: )
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