I have been having a problem with my '04 Road King Classic throwing codes P1353 & 1356 which means no combustion in the cylinder. It all started when I took off a DFO and installed a Ness Big Sucker and a V&H FuelPak. I also have V&H Basic slip-ons. Took it to a dealer and they reset the codes and said it jsut happens once in a while. It kept happening so back to the dealer. This time they thought it was the FuelPak so we took it off and did a remap of the ECM. Few miles down the road and the check engine light was back on. So again back to the dealer. This time they put it through a thorough diagnostic test. Turns out what was causing the bike to throw the codes was that I was running non-Harley plugs. I have to do with the dealer on this one. They checked out everything else. And it makes since because I installed a set of Champion plugs just before I did the Big Sucker and FuelPak. I had suspected the plugs and relaced the Champions with a set of NGK's. Still didn't help. The dealer installed a set of Harley plugs and ran the bike for over a half hour on the dyno and could not get it to throw a code. I have been emailing TCSTD on this and he agrees with the findings. I also got this response on another forum:

That is very true actually. The ECM reads the resistance of the plugs, plug wires and coil to make sure that there is no knock in the system and to advance throught the MAP correctly. If you change the resistance no only do you risk getting a CEL but you risk the ECM thinking the bike is knocking when it really isn't and therefore running the MAP incorrectly. Had this same issue on my bike when I installed a custom set of plug wires. Bike seemed to run fine but I would notice little nuances every now and then so I learned this the hard way also.

Hope this helps anyone out there experiencing the same problems I had. If you are thinking of changing plugs, you might want to reconsider if you are buying something other than Harley plugs.

 

What an interesting problem/fix. Glad you got it sorted out.

 

George, I'll bet you never checked the DIY forum........I'm gonna get a rubber stamp made for that

https://www.hdforums.com/m_98758/tm.htm


...............with a GIVEN set of Production intent parts.ie , Spark plugs, wires, and even compression ratio can and does change the resistance at the coil. So once folks start changing wires, Plugs ( to non-factory specs) and modifing the engine cams, compression ratio etc,( and even expected A/F ratios, and therefore combustion temperature) the values derived form a production engine are no longer valid and may cause the software to "determine" that knock is present when it's not or fail to dectect knock when it is.

 

TC,

Oh how right you are. My learning curve has been long! I may start switching my bike back to all Harley parts. Air cleaner and pipes. I do know that my next Harley will not see anything but Harley parts. I think that for either buck I think I was going to save it cost me two.

George

 

George

I found over the years that things like oil filters, plugs ,wires and other Harley specific parts that are specked for these bikes are best bought at the dealers. I've heard comments about aftermarket oil filters giving better oil pressure and other brand plugs or wires running better which if I was paid to substantiate, I just couldn't do it. If there is more oil pressure with an aftermarket filter, there's something wrong somewhere because if it were specked to HD specs for these motors, it would make no difference in pressure at all. I'm not about to spend $30 K on a bike and look to save $3 on a filter. It just doesn't make sense to me at all. The ion sensing in these motors retards the spark when it senses knock and to replace the plugs with another type defeats the system. Again here, where's the advantage here? I dislike giving the dealers my money for anything but there are just some things we cant get around with parts without causing ourself a problem.