Engine studder below 2000 RPM

[hinglby]

Hello everyone. I've searched the forum and didn't fine any help.

My 2005 Rocket has developed a problem below 2000 RPM (80,000 mile is ran perfect). About 75% of the time the engine will studder/hesitate when giving it medium to hard throttle below 2000 RPM. Example: When approaching a left turn at an intersection, down shifting 5, 4, 3, 2, leaning into the corner and starting to accelerate. There is hesitation, studder then all is fine. When I start off in first, shift to second prior to 2000 rpm and throttle up hard, it stumbles and studders.

Things I've done since problem started: replaced fuel filter, spark plugs, primary TPS (Twice), secondary TPS, verified TPS's adjustment (5 times), checked all vacuum lines (twice), checked coils and wiring (twice), checked O2 sensor wiring, MAP sensor wiring, intake air temp wiring and verified stepper motor function/adjustment. I've reloaded the 20227 tune, downloaded the current 20227 tune and down loaded, tried 20050 and 20226 tunes. Pulled the ignition switch and verified continuity along with visual inspection of solder joints.

It's weird, if I hammer down and keep the RPM's over 2k, all is fine. It acts like an old carburetor with a clogged idle jet. The only thing I noticed was slightly low voltage on the O2 sensor output. It's within limits but a little low. Not sure $177 part swap is a good thing.

Thoughts?!?!

 

[warp9.9]

I got to ask doe sit only do it when you lean in left hand turns or does it do it when leaning into right hand turns?
What the throttle boy balance look like and have you check the plug in from the main harness to the fuel rail harness and the injector plugs for good contact and cleanliness?

 

[hinglby]

Hi Warp... Leaning makes no difference, it studders left, right and straight. Throttle balance seems fine, all three cylinders are within 5 of each other (470-475 at idle). The injectors are clean, secure and the plugs are firmly in place. I checked the main harness and all connections from the ECU to everywhere I can find.

I'm going to try and run the data logger as I ride around to see if anything unusual is revealed.

 

[RocketEd]

Have you checked/cleaned Crankshaft Position Sensor?

 

[hinglby]

Hello RocketEd, Yes, several time to be sure.

 

[RocketEd]

Well, crap, Cap'n, I'm out of ideas for now.

 

[hinglby]

Me too! I just changed the spark plug wires and verified that the coils are securely wired. I swapped the position of two of the coils to see if anything changes.

If this doesn't help I guess I will have to purchase the O2 sensor.

 

[RocketEd]

Can you choose to have your tune ignore the O2 sensor?

 

[warp9.9]

I am starting to wonder if since its lower rpms and higher engine load/vacuum if your Maps sensor is not playing up. But I must admit I am starting to guess!!!

 

[hinglby]

I'm not familiar with turning off the O2 sensor. I'd have to read up and see if or how to do it with tuneboy.

The data loader shows the MAP sensor reading and it appears the same as my friends RIII Touring (since the manual gives no readings). My O2 sensor on idle is reading .95 when the RIII Touring reads 1.975. Wondering if its the problem.

Still trying to get my fried to let me borrow his sensor to troubleshoot.