2021 Defender Knocking and stalling

[plumber802]

I ONLY use non ethanol premium (91 octane) fuel in my HD8 with no issues. Good to hear you got yours fixed.

 

[lonestar 2021]

i had the same issue with my 2021 lonestar, i took it to destination cycle in kerrville and they had it for a day and ended up changing out the IAC valve and that cleared it rught up. i have had it for about 2 weeks now and no issues. thank you destination cycles

 

[honda400ex2003]

Some other things to check for others reading in the future-

Just went though this with mine, put plugs in it and so far it's been good. Gap was .010" on one of them.  Fuel pressure was good and was heading towards tps sensor and crank sensor when someone suggested plugs on Facebook so I figured I'd give that a shot.

.031"-.035" is spec for the hd10 for gap.  Fuel pressure should be 51+/-1 psi as well if anyone checks it.

Mine was running rough, misfiring and chugging bad at 10, 20, 30mph.  Didn't matter if it was 87 or 91 octane.  

Just glad I didn't need a regular like the op.

Steve