PV Knock Retard Front Cylinder Only

Started by vtwinjim, November 26, 2021, 09:26:26 AM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

vtwinjim

110 2015 CVO Limited

PV installed about 3 years ago.

Bike started knocking a few weeks ago. Downloaded the log from PV.
For some reason it is only retarding the front cylinder. I looked for a switch in WinPV that would do this but didn't find one.

Any thoughts on what can cause this?

I'm going to reload map to see if that helps.

rigidthumper

You can edit just the front timing table in any specific area, if you're convinced everything else is OK.
Ignorance is bliss, and accuracy expensive. How much of either can you afford?

HV

One thing to look at....with bikes that have a lot of miles on them we see a lot start to carbon up bad and more on the front then the rear as the rear runs hotter ...this causes detonation due to the hot Carbon ....it will detect more on the front and pull timing to compensate  run some combustion cleaner through it may help....worth a try ...Its really more pronounced with the High compression M8s  but Ive seen Twin cams do it as well 
HV HTT Admin ..Ride Safe ...But Ride informed with HTT !!
Skype HV.HTT

vtwinjim

I've scoped both cylinders and neither has much if any carbon build up.

What I don't understand is how PV would know to retard just one cylinder when I believe it only gets temperature from one MAP sensor and one Head temperature sensor.

Shouldn't PV knock down both cylinders the same amount?

rigidthumper

The ECM uses an 80 volt signal sent down the plug wire immediately after combustion to check for the presence of ions. This ION sense data is used to detect detonation about to occur, or occurring, and the ECM will retard timing as it feels is/will be necessary. Aftermarket plugs & wires can alter this signal, causing false knock retard events. Easiest way to ensure you have actual issues or not is to make sure you're using stock spark plugs & wires, with firm contact between the plug wire terminals and the spark plugs. If all that is good, and the system is indeed pulling timing in that one area consistently, you can add fuel, reduce spark advance, or both, for that cylinder in the PV map, to address the issue.
HTH
Ignorance is bliss, and accuracy expensive. How much of either can you afford?

hrdtail78

As RT stated.  Each cylinder is treated independently.  A couple of things that can cause this on a well tuned engine that I suggest checking before addressing it in the tune.  Fuel pressure, fuel filter, plugs, screw on tops if not using solid plugs, plug wires, bad fuel......
Semper Fi