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HELP! Engine bobble between 1300-1800 rpm.

bryguyslc

bryguyslc

Member
New guy here so sorry if this is in the wrong place. I am currently riding a 2003 FLHTCUI and it is now running a 103 CID SE conversion and is built up pretty good. The engine build included: going from the stock 9:1 pistons to 10.5:1 pistons bored 10 over, the head was also milled .010, went from the stock 45mm throttle body to a 55mm, larger valves, roller rockers, High Performance valve springs, SE 258 cams, adjustable push rods, Hybrid hydraulic conversion cam plate with Zippers dual piston cam chain tensioners (just finished this part actually!), High performance roller lifters and a high flow oil pump......ummm, I think that is most of it.. I now have a bobble between 1300-1800 rpm. I have checked the wires, changed the plugs and the fuel. any ideas?
 
What are you using for a fuel tuner? When you say "bobble", does that mean it backfires and if so from where? Does it just stumble? Did it always do it, or did it just start doing it? What was the last thing done before the "bobble" started?

Welcome to the forum!
 
Bodeen said:
What are you using for a fuel tuner? When you say "bobble", does that mean it backfires and if so from where? Does it just stumble? Did it always do it, or did it just start doing it? What was the last thing done before the "bobble" started?

Welcome to the forum!
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Oops...sorry and thanks for the reply. Tuner is a power comander V, loss of power no backfire just sputters and wants to die, just started doing it on first rides after I was done with the cam plate conversion. It runs out great once it hits 2000 RPM.
 
Try the wiggle test. Wiggle the injector wires while its sitting still and see if you can make it stumble. The wire right up to the entry to the injector.
 
Also I noticed that it idles fine but when you rev it up then let it fall into that rpm range and get back on the throttle as it drops into that rpm range it will die.
 
Unplug the Power Commander and try without it in the loop at all. It wont run perfect because it will be lean but check to see if the dead spot goes away. If it does you found the issue.
 
Check the coil resistance and check for loose or broken wires, have you checked your voltage out put?
 
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