Solving Spark Knock
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Road Warrior
Joined: Apr 2006
Posts: 1,621
Likes: 1
From: Matthews, NC
Solving Spark Knock
I am getting spark knock in 5th and 6th gears (sounds like loose change in the front cylinder). I am using Chevron/Texaco 93 octane. What can I do about this?
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Road Warrior
Joined: Apr 2006
Posts: 1,621
Likes: 1
From: Matthews, NC
RE: Solving Spark Knock
ORIGINAL: Norm
How long has this been doing this? Did it start after refueling? Any mods? Need a little more info.
How long has this been doing this? Did it start after refueling? Any mods? Need a little more info.
Cruiser
Joined: Dec 2005
Posts: 180
Likes: 1
From: Harrisburg, PA
RE: Solving Spark Knock
+1 with what hotpursuit said. No check engine lights, no codes. I don't really thing your additive will hurt but, I don't think it will really help either. I'd also try a different brand fuel just to see if there is an improvement. I'm sure you just didn't start lugging in the last two months. Don't the 07's have a knock sensor?
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Road Captain
Joined: Oct 2007
Posts: 634
Likes: 8
From: Plum & Nearly
RE: Solving Spark Knock
Have you changed plugs or wires that are not H-D? Could affect "ion sense". Search if the search is up for an explanation.
Also the calibration that you might want to look at...
the last bulletin was issued 2-7-08 and was M-1186A (product program 0903) regarding calibration upgrades for 2007 big twins...this should be free but you would need to talk to your dealer to see what you currently have.
good luck
Also the calibration that you might want to look at...
the last bulletin was issued 2-7-08 and was M-1186A (product program 0903) regarding calibration upgrades for 2007 big twins...this should be free but you would need to talk to your dealer to see what you currently have.
good luck
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Road Warrior
Joined: May 2006
Posts: 1,479
Likes: 4
From: SoCal
RE: Solving Spark Knock
A safe short-term solution to engines with knock sensors is using 10, 20, or up to 30% toluene or xylene (chemical or paint supply stores, about $ 3.50 / gallon) to increase the octane rating and raise the knock threshold. Engines with knock sensors retard the retard the spark timing (robbing you of power) at the onset of knock. This higher threshold will allow combustion and charge expansion to occur so that more force is put into the power stroke. However, higher octane fuel only helps you make more powerat the verge of detonation, so a tuning device is still the most cost-effective long-term solution. Cooler thighs too! 
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Road Warrior
Joined: Apr 2006
Posts: 1,621
Likes: 1
From: Matthews, NC
RE: Solving Spark Knock
I just checked with HD. There has indeed been an issue with spark knock in many 2007's. They have issued a FREE download to resolve this problem. If any one needs it, it is on HD's Digitial Tech 2, part number 32903-07E. Mine will be installed tomorrow morning. Thanks!!!