I have an 09 Fat Bob, T-Max EFI, has been running great with exception to some decel popping. Just recently thought I'd try the much touted NGK iridium plugs. One pster claimed that they stopped his decel popping problem, that's my excuse. Anyway, I'd read and heard those plugs would cause the ECM to shut off the "spark knock" feature that automatically retards the timing if the ECM detects that condition.

I didn't get the bang for buck out of the NGK plugs that I expected and they didn't solve my decel pop isue, so I switched back to stock HD plugs after just a few rides. That was several weeks ago .. just over the last few days I've noticed a ping when accelerating in 4th 5th, 6th gears from upwards of (I'm guessing, don't have a tac) 2200 RPM. Weird thing is that it doesn't ping until I hit that range.

I thought bad gas to begin with because I haven't changed anything for quite a while. But after several fills at different stations, Chevron, Union, Shell, never one of those quickie marts, still have the problem.

So, my questions is assuming the spark knock feature did get turned off somehow, is there a way to turn it back on? I can easily retard the timing, but didn't want to mess with that just in case the spark knock feature is what's possibly wrong.

Also, question, does anyone think that having used the NGK plugs for even a short period may have permanently damaged my ECM?

Thanks,
Tom

 

Tmax don't have ion sensing. If you can find the rpm zone for pinging then drop that rpm range 1-2 degrees to stop it. Read manual on how to set timing. Plugs have no effect on decel pops. Depending on where the pops are occuring it will require activating the decel cut function and setting it's rpm ranges or low low rpm edits to afrs. Dump the fancy plugs and stay with the stockers. Most of the claims are
Ron

 

Ron:
Thanks, I just assumed that the T-Max had same as OEM with respect to all the wires that are connected, ex; Ion sense wire coming from the coil..

Anyway, will back the timing down a bit until I get the pinging to stop. Weird that it only started recently.

I've tried the decel cut with two different maps so far and didn't seem to make any difference regardless which RPM high / low limits I put in. I had help from Zippers, ref: limits, via monitor logs etc. Just never seemed to work for me. Oh, and I did reinitialize the module to be sure.

Question: What AFRs would you recommend at low low RPMs, I'm assuming that you're referring to RPM values at or below idle?

The pop usually occurs with throttle nearly or completely backed off, usually only if I maintain a steady (2000 - 4000) RPM for an extended period, then decel.

Thanks,
Tom