Try to figure this one out.

Sympton: Bike gets false reading (ghost codes) on the computer. The codes are saying misfire codes on the front and back cylinder. And some codes have even come up saying there is compression lost on the front and rear cylinder of the bike. Oh, almost forgot to add this as well. The bike's speedometer was acting up. The speedometer was bouncing, or jumping, if I was going 35, it would bounce up to 40mph, and then back down to 35, it would jump an average of 3 to 5mph.

What was done to the bike to possibly cause this.
2007 Ultra Classic
I have changed exhaust system. (True Dual's)
Arlen Ness air system
Power Commander PCIII
NKG spark plugs
Ultima spark plug wires.
And YES the bike was Dyno...

Solution:
After about a week of tracing down the source. Believe I have found the source of the problem (THE SPARK PLUG WIRES)....

We have changed out the wires (went to SE plug wires), and plugs, and guess what. NO MORE SYMPTOMS. And yes the speedometer is working correctly now.

They state these wires (Ultima) are: 8mm plus, 40 ohms of resistance per foot, which gives the highest spark energy transfer and the highest EMI/RFI supression. KevlarŪ core center with a nickle copper alloy conductor wire, which is wound 124 times per inch.

I am wondering if anyone else has had this type of problem or symptoms with there bike, and have made the same conclusion.. Would like to hear from you, and thanks

ToadsUltra

 

On the late model bike the spark plug wires are part of the computer sensor array. They use some type of feedback (ion I believe ) to talk to the computer. Changing wires to a high performance wire that has a different signature could/will give you false codes. The same is true I believe about the spark plugs. This is just another way that the MOCO makes you spend your money with them. Hope this helps.

 

I also was getting stored dtcs in the computer for rear cylinder misfire. The bike seemed to run fine. no speedometer issues though.Followed the diagnostic tests in the manual, to no end. Finally read a thread hear about similar problems. Mine was ,I had put in NGK iridium plugs. Switching back to Harley plugs eliminated problem.

 

Thanks,

It does in a way explain the problem, and why.

Just in a way, wish there was a way around it. With the those spark plug wires, you could really see a difference in the spark fire. Had it on a tester, and compared the stock, to SE, to Ultima wires. The Ultima wires, had a hotter, deeper blue spark, compared to the others.

Thanks,

ToadsUltra07

Seen this shirt the other day, it brought a laugh to my wife and I.
Stock bikes are like tampons, every ***** needs one.

Might make it my signature, LOL. That is if the Admins. dont get fussy about it.

 

My 2004 V Rod is having sparg plug coil issues. No spark to the rear plyg. I replaced the spark pmug coil and still same problem. I switched it to front then front would not fire. I switched it to back and back would not fire. I took original coil and stretched the coil spring inside of wire and it ran great till cooldown. I started the bike and the miss came back.

 

................Holy old thread, Batman!