G oog le BadWeB | Login/out | Topics | Search | Custodians | Register | Edit Profile


Buell Forum » XBoard » Archive through December 02, 2010 » Unstable idle « Previous Next »

Author Message
Top of pagePrevious messageNext messageBottom of page Link to this message

Socalbueller
Posted on Tuesday, October 26, 2010 - 01:06 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Iíve been having this issue for a while but it got bad enough for me do something about it. It got to the point when cold my bike wouldnít idle unless I cracked the throttle and tried holding it around 2k. What happened when I started it would idle about 1200 rpm for 2-3 seconds and just die like it ran out of gas. I would restart it and hold the throttle so it would be at 2000 rpm and after 3 seconds it would chug down to 1000 then rev up to 2000 then back down to 1000 and so on all with out moving the throttle from where I had it to keep it at 2000 rpm. As it warmed up it would eventually stay running but would idle about 700rpm. When fully warmed up it would idle at about 800-900rpm. Resetting the TPS did not make any difference.

In the past week or so using ECM spy I have found a bad head temp sensor, the timing was retarded and a possible bad O2 sensor. I also checked for intake leaks and found none. I have since corrected the timing, replaced the head temp sensor, replaced the O2 sensor, and reset the TPS. It is running much better, mostly I think for the corrected timing, but still wonít idle when cold (warms up faster though). When fully warmed up the idle will climb to 1300 rpm then drop to 800 then in 4 seconds will be back to 1300 rpm and drop again. The readings from the TPS look good Iíve opened the throttle slowly and didnít see any jumps and snapped it open a couple times and the readings remained consistent when shut. Off idle it runs great has a lot more power then it did a month ago. Itís just at idle it runs like ass.

I have been looking at the readings on ECM spy when the bike is warm and idling I am not sure what I am suppose to be looking for but the only thing that looks strange to me is after 30 seconds or so the O2 sensor stays at .1 volts. If I give it a couple revs it seems to wake up and bounces between .6-.2 volts. Also I noticed looking at the injector pulse width it is between 3 and 4 goes to a 2 when the idle drops to 800 rpm, then back to 3-4 until it hits 1300 rpm again.

Is there anything else I could check or does anybody have any idea what the issue could be? I think all that is left is the TPS and air temp sensor. Like I said the TPS looks good and the air temp sensor reads correctly from what I see on ECM spy.
Top of pagePrevious messageNext messageBottom of page Link to this message

Terrys1980
Posted on Tuesday, October 26, 2010 - 09:49 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Have you burned any EEPROM changes to the ECM lately? I have had similar symptoms after what I thought was a successful burn. I burnt the stock settings after wards and the bike ran good.
Top of pagePrevious messageNext messageBottom of page Link to this message

Socalbueller
Posted on Wednesday, October 27, 2010 - 12:28 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

No changes to the ECM it is still stock. I still have the stock muffler but I did take out the snorkel years ago and this past summer put in a K&N. I'm not sure that would have anything to do with it since you set the idle speed by the throttle stop cable. I could understand the K&N causing a high idle but it shouldn't cause my cold start symptom.
Top of pagePrevious messageNext messageBottom of page Link to this message

1_mike
Posted on Monday, November 01, 2010 - 05:38 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

PM sent

Mike
Top of pagePrevious messageNext messageBottom of page Link to this message

Petebueller
Posted on Tuesday, November 02, 2010 - 02:07 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

You could check your TPS volts at idle to see if they are fluctuating.

Also you could look to see if you have a broken throttle butterfly shaft.

The IAC is also a possibility
Top of pagePrevious messageNext messageBottom of page Link to this message

Socalbueller
Posted on Tuesday, November 02, 2010 - 07:59 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

The TPS is ok and idle was pretty consistent going up and down I would think a broken shaft would be more inconsistent. Wouldn't hurt to check it though.

None of that matters now anyways since I am pretty sure I have a bad rod bearing. Happened Saturday while doing a track day. Not sure what I am going to do next.
Top of pagePrevious messageNext messageBottom of page Link to this message

Petebueller
Posted on Wednesday, November 03, 2010 - 03:10 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

When the shaft was broken on my friend's bike the idle was really erratic. The other telling sign was that it wasn't possible to set the TPS consistently.

I hope it's not the bearing. Maybe worth checking the oil pump drive and oil pump.
Top of pagePrevious messageNext messageBottom of page Link to this message

Socalbueller
Posted on Friday, November 05, 2010 - 01:37 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Hmmmm... the TPS does move a little if I check it after a few days, not by much though. It still hunts at idle though with the reading being consistent through the day. The oil pump gear and pump were replaced less than a year ago. Still not sure what I am going to do about it.
Top of pagePrevious messageNext messageBottom of page Link to this message

Petebueller
Posted on Friday, November 05, 2010 - 07:14 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

A friend had a noise diagnosed as a big end that turned out to be a lifter. I hope you don't have to split the cases.

A broken butterfly shaft is a possibility still. I have seen that cause the same sort of fluctuation at idle.
« Previous Next »

Add Your Message Here
Post:
Bold text Italics Underline Create a hyperlink Insert a clipart image

Username: Posting Information:
This is a private posting area. Only registered users and custodians may post messages here.
Password:
Options: Post as "Anonymous" (Valid reason required. Abusers will be exposed. If unsure, ask.)
Enable HTML code in message
Automatically activate URLs in message
Action:

Topics | Last Day | Tree View | Search | User List | Help/Instructions | Rules | Program Credits Administration