| Author |
Message |
    
Tocramed
| | Posted on Sunday, July 20, 2008 - 10:06 pm: | 
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Hello all,
I have just over 2k miles on my bike and it started detonating. Seems to only do it when it gets hot and with a decent amount of throttle.
The dealership has looked at it twice, adjusted the static timing both times, but nothing else. Both times the problem cleared up for a few days and they just say everything is fine.
Right now the timing is perfect, plugs are good and correct heat range, leak down test was good (2-3%), and there is no excessive carbon buildup (had it scoped).
Has anyone else had this problem? Is this common? Any help would be greatly appreciated.
Thanks |
Second_strike
| | Posted on Monday, July 21, 2008 - 11:27 pm: |
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could it be bad gas? i had that happen to me in my mustang. try a SMALL amount of octane boost. |
Bombardier
| | Posted on Monday, July 21, 2008 - 11:41 pm: |
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If you have access to ECMspy and megalogger check the response time for your O2 sensor(megalogger and what the afv is showing(Ecmspy).
If the map is too rich it will adjust the afv to compensate. This combined with a poisoned O2 will give you the lean rattles when the throttle is applied as the O2 is slow to adjust the mixture.
Forgot to mention that f the engine temp sensor has gone out of range( the test procedure for this is in the service manual) it will not be calculating the correct temperature correction and will lean out the mixture excessively.
(Message edited by Bombardier on July 21, 2008) |
Sloppy
| | Posted on Tuesday, July 22, 2008 - 01:20 am: |
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Fairly common detonation problems during high ambient temp and high load applications -- I assume you're using the highest octane available in your area (Pump 91?)
Use a plug with a step or 2 colder range. My preference is NGK. I use a step colder than recommended and have no fouling issues. |
Tocramed
| | Posted on Tuesday, July 22, 2008 - 09:55 am: |
|
This has been happening for several hundred miles for sure. I have filled up at a couple different stations and I only use 93 octane (92 once).
My plugs are NGK iridiums, the heat range is 8. I was going to try putting some stock plugs in to see if that helps.
The ambient temp seems to be playing a big role. I have noticed it more when the temp is above 80F. Last night the temp dropped into the 60s and even when trying to get it to detonate, it was doing it less. The only new mod since the NGK plugs is, last night I rerouted my breather lines to a catch can. Maybe that was helping as well???
I don't have access to ECMspy or Megalogger, but I have a feeling that this is something that I should invest in.
The plugs seem fine. The odd part is they do not show any signs of detonation or fouling. |
Bombardier
| | Posted on Tuesday, July 22, 2008 - 09:59 am: |
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Ecmspy is free.
Megalogger is a $20 donation. |
Tocramed
| | Posted on Tuesday, July 22, 2008 - 10:10 am: |
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Really?...cool. I guess I haven't looked into it enough yet. Off to ECMspy.com I go.
Thanks! |
Sparky
| | Posted on Tuesday, July 22, 2008 - 03:26 pm: |
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Rerouting the breather hoses may have a big part to play with this problem because the vapors from the hoses are, no doubt, hotter than the outside ambient air coming through the air filter.
Inside the air box is the Intake Air Temp sensor which may be correcting mapping based on the ambient temp plus the hotter breather vapor temp.
This is just conjecture on my part, though; I have not measured breather hose vapor temps nor temps inside the airbox. But it kinda seems like there may be a connection there.
Regarding the IAT, clean it carefully & gently with a isopropyl alcohol soaked cotton swap if it appears to have any kind of residue on it. |
Bombardier
| | Posted on Tuesday, July 22, 2008 - 08:19 pm: |
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Here some material that will help you understand the Buell fuel injection system.
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Tocramed
| | Posted on Tuesday, July 22, 2008 - 11:02 pm: |
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Thanks everyone. I have ECMspy and a new cable on the way. I will let you know what I find out.
The IAT looks clean, I never really had much of an oily residue around the intake.
It was a little cooler this evening (low 70s) and it was still detonating, but I really had to get the engine hot and give it to hear it. I still don't think this should be happening with the temp in the 70s or even at 90 or 100 degrees for that matter. |
Sloppy
| | Posted on Wednesday, July 23, 2008 - 02:46 pm: |
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If I recall NGK's plug numbers correctly (that's a big "if"), you'll want to go cooler, at least a 9 or try a 10 if available.
Cooler plugs made a significant change to the detonation tendencies of my bike. |
Tocramed
| | Posted on Wednesday, July 23, 2008 - 03:16 pm: |
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I am sorry, the proper heat range should be 9 which is what I have. I bought the plugs from a small, non-Buell parts dealer who said all Buells take 8s. Well, if I am correct, all XBs take 9s and it was the older models that used 8s. The 8s did cause my bike to detonate the majority of the time; they came out just about as fast as they went in. |
Tocramed
| | Posted on Monday, August 11, 2008 - 03:00 pm: |
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If the engine is running lean because of a faulty ET sensor (or any reason) in turn causing it to detonate, would the AFV show a value higher than 100?
The thought leading to this question was...if it is running lean, would the AFV be trying to compensate? |
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