Hello,

I have 2006 Heritage Softail Classic, Fuel Injected. I have the weird 'sucking' sound intermittently, happens every few minutes. I attached the recording of how it sounds at idle, but basically I can hear the same sound while riding. Engine seems to be a bit jerky at lower RPM as well.

Any suggestions of what is causing it and how to resolve it? I changed already fuel filter, fuel pressure regulator/housing (this was actually cracked), fuel lines, throttle position sensor. I measured ignition coil and it measured within spec, both primary and secondary windings. I put in new spark plugs as well.

Thanks,
Erik

 

Can you isolate where the sound comes from? A few times it sounded like a chirp. Which may indicate a lifter roller. How many miles on the motor?

 

I can't open your attachment but if you believe you have an intake leak look for it with a small propane torch bottle. Put a length of rubber hose on the end and just turn the gas on and slowly run it around all the intake joints while the bike idles. If the idle changes then you've found the leak. This is my preferred method over spraying flammable and caustic fluids all over the bike.

 

Engine has 44K miles on it. I put in new Feuling HP+ lifters, S&S TC3 fuel pump and cam plate and Feuling Reaper 525C conversion cams. However, I had this sound also last year (stock cam plate/lifters), but much less frequent. Bike has straight pipes and K&N high flow filter.

 

I tried with WD40 but couldn't find any leak. Let me try with your method as well, though. May be easier to find a leak...

 

Does it pop on decel?

 

A little but I had a bigger pop with stock setup, as far as I can tell.

 

Usually popping or backfiring on deceleration is an indicator of a intake leak. You can take your time with lp bottle, no mess.

 

Doesn't look like intake leak, I couldn't detect change in RPM. One other thing, using stock fuel map, idle seems fine. However, using map for new cams (I have Dynojet PV4, map was sent to me by Fuel Moto, specifically for my bike), engine seems to almost die and 'sucking' air is much more frequent. I captured some datalog and AFR seems to be way too low with new map - around 12, 12.1 - although based on RPM/TPS and AFR table, it should be around 14.

I also ran bike without PV4 connected, issue was still there.

 

Sounds like it could be mapped wrong. Can you modify AFR's?