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Buell Motorcycle Forum » Old School Buell » Archives OSB 001 » Archive through September 25, 2007 » S3T hesitation/stumbling problem « Previous Next »

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Yo_barry
Posted on Wednesday, September 19, 2007 - 04:05 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I have a 2001 S3T with about 42K miles, race ECM, gutted airbox with K&N filter, Supertrapp exhaust.

The bike doesn't like to run at a steady speed in the 2600 to 3000 rpm. If I'm riding at that speed and try to accelerate it stumbles and hesitates before going. Also tends to stumble a bit just riding steady speed at that RPM range.

I had the TPS set when I installed the race ECM about two years ago. Does that need to be reset occasionally? Any other thoughts or suggestions on what causes this? Maybe it's just something I need to continue living with..

Thanks,
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Sloppy
Posted on Wednesday, September 19, 2007 - 06:32 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

A similar thing happened to me with my supertrapp -- a bolt that holds the discs in the muffler sheared off and allowed the disc assembly to move back and forth in the muffler. As I accelerated the disc stack would plug my exhaust. Make sure this one little screw on the bottom of the muffler is still there.

Other items to try:

Clean the inside of your throttle body, especially around the throttle plate.

Run your bike in a closed loop condition for its DDFI to learn your bike's settings (it's in the Service Manual or do a search here).

Check for an intake seal leak.
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Iamike
Posted on Thursday, September 20, 2007 - 10:10 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

My Supertrapp did the same thing this summer. I had just read a post from someone else that had the problem and looked underneath and the screw was missing.
I couldn't push air through it so it had no power.
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Naustin
Posted on Thursday, September 20, 2007 - 10:32 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

My Supertrapp did that too. THe bike ran like CRAP, and would not rev over 4,000 rpm. THe whole baffle shifted backwards and almost totally sealed off the muffler by pressing up against the venturi deal on the end cap.

That said, I don't think this is your problem. You would know you had a major problem if this happens to you and you'd be afraid to even ride the bike.

Check your intake seals! : D I always say that, anytime anybody uses the word stumbles/hesitates/surges etc. etc.

Good luck.

Nick

PS, I have an `01 S3T (BLue) with Race ECM and Supertrapp too.

(Message edited by naustin on September 20, 2007)
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Yo_barry
Posted on Friday, September 21, 2007 - 12:09 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Thanks for the input. I'll have a look at this stuff over the weekend.

I'm sure I don't have a Supertrapp problem as described, but probably should take it apart and repack it. It's getting a little noisy.

Barry
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Duckbuell
Posted on Friday, September 21, 2007 - 11:19 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Hi Barry, my 01 S3 was cutting out, surging and running really bad at 2600-3000 rpm. I hooked it up to the VDST diagnostic tool and the ECM was storing error code 11. Error Code 11 indicates a faulty Throttle Position Sensor (TPS). It would do no good to simply re-set a TPS that has gone bad.
It was a $35 part - runs like a champ now.
Perhaps the dealer can check for any error codes for you.
CHeers!

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Ratbuell
Posted on Friday, September 21, 2007 - 11:56 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

If you're without VDSTS tools, you can do a quick TPS check with a needle-gauge voltmeter(you can use a digital display model, but it isn't as clear a process). Just pull the TPS, figure out which are the hot (+) and signal terminals via the shop manual, hook the leads to the meter, and sweep the sensor thru it's range with a screwdriver to simulate real action. The needle (with the voltmeter set on resistance, or Ohms) should give a clean sweep from one end of the display to the other with no hiccups or jumps. A hiccup indicates a dead spot or a short.

Think "volume knob" - that's all it is when it comes down to it, a potentiometer that tells the computer where your throttle blade is sitting so it can set fuel and spark.
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Yo_barry
Posted on Saturday, September 22, 2007 - 10:48 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Hey thx Ratbuell... I pulled the airbox and throttle body. Found the throttle body to be really dirty (oily) behind the throttle plate. Cleaned up same.

Don't know if I had a leak but decided to replace the throttle body gasket. Also found a frayed throttle cable and a cracked plug over the CA vacuum fitting. Ordered new cables and gasket. Replaced the plug.

I'll check the TPS with a voltmeter and then wait for the new parts to get here.
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Yo_barry
Posted on Sunday, September 30, 2007 - 10:48 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Just to close this out... I cleaned the throttle body as it was really dirty behind the throttle plate. I don't know if I had a leak or not but replaced the throttle body gasket. Also replaced the plug over the CA port on the bottm of the throttle body, the one on there was split. Installed new throttle and idle cables. Also verified the TPS operation with a voltmeter as described.

Results?? Well, no stumbling between 2k and 3k RPM and overall seems to run really strong. I can't remember it running this good!

Thanks for all the help.

Barry
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