I need some help in diagnossing an engine stumble or miss. First I have a 01 RK with 31000 miles, 95 in. with 253 gear drive cams, PIII, map is a custom that was done when dynoed. Today I noticed the idle was slightly lower than usual. Later this afternoon, it started a stumble just off idle, intermittened when using 1/4 throttle. Felt like a spark plug miss( but no backfire) or maybe a fuel inj. hesitation. Also seemed to be lacking the usual power. When I used more throttle, no problem runs great. Tonight coming home from work. it got worse. Heavy miss off idle and continued some what but still pulled great when given more throttle. I pulled the plugs and they are clean although a little carbon on the ground elect. the map is a little rich in some areas. This scoot has always ran perfect. It has a half tank of fuel. Fuel pump sounds good. I have heard that some fuelees have inj. wire issues. Is this an internal wire problem? External wires look good although I have not check with a multimeter. Any ideas? I have experiance with carbs. but no fuelees on scoots.
Thanks,
Dave

 

Dave unplug the PCIII and ride it again....if it doesn't miss it's your PCIII....if it does still miss Check for codes, if yo udon't know how to check the codes take it in to the dealer so the techs can put the Digital tec on it to find the problem

 

Check the battery connections. Cut & paste from my early school notes in case you need them:

RADIO PROBLEM DIAGNOSTICS

To enter the radio diagnostic mode, press any two (2) station preset buttons simultaneously while turning ignition on. There are five (5) diagnostic modes (D1-D5) plus Automatic Volume Control (AVC) setting. Digits will change from 0 to 1 when function button is operated. If digit does not change, there is either a short or open on that circuit (see Service Manual or ED for codes). To cycle through the various diagnostics, use the LO/DX button.

D1: Switch Function Mode will display a five (5) digit binary code at the top of the LCD.
Digit 1=Mode set, up & down
Digit 2=FPTT, RPTT, Volume up & down
Digit 3=Audio in, Squelch-, Eject
Digit 4=Audio-, Squelch+
Digit5=Audio+

D2: LCD displays an 8-digit code
Digit 1=PTT microphone Digit 2=Vehicle speed Digit 3=VOX break Digit 4=CB SQ break Digit 5=IC on/off Digit 6=CB on/off Digit 7=SPKR SW B Digit 8=SPKR SW A

D3: LCD function=Illuminates all display items in LCD.

D4: Model year=Select model year as prompted.

D5: Software=Displays software information

AVC: Automatic Volume Control=Adjusts volume to engine speed. 0 to 4 range with 2 the factory setting and 4 being the most aggressive setting.

ENGINE PROBLEM DIAGNOSTICS

Engine Light function: Normal operation=light comes on for four seconds after IGN SW on, then goes out if no present DTC. DTC in History=light comes on for four seconds after IGN SW on, then goes out, then comes on for eight seconds, then goes out. Current DTC=Engine light stays on after IGN SW on indicating current fault (note: some codes will only trip at engine run i.e.: CKP)

Speedometer diagnostics (WOW Test): To access function, hold in speedometer trip reset button while turning on IGN SW to ignition or run position (engine start/stop sw must be in RUN position or it will display "no rsp" for ECM). Press reset sw to cycle through selections, then hold in to select that function. Hold in again to clear from history. Start bike and recheck for recurring codes (current).

P=ECM & P/N S=TSSM & P/N SP=Speedometer & P/N T=Tachometer & P/N (if equipped)
*Part number of component follows each item after pressing reset button.

 

Thanks for your imput Doc and Robzuc. I don't think I can unplug the PIII as it seems to be hardwired to the ecm... and the check engine light never has flashed but I still checked for a DTC and it was clear. I have no radio so I cannot use those procedures. Tonight I ran it up to temp ( in the garage) and wiggled the inj. wires did not miss a beat and checked the tank for any odd noises inside, none. I guess I will check the plug wires next and see if they are arcing on anything. The only other thing I can think of is to replace the fuel injs. and the PIII.... I just hate replacing parts untill it's fixed. Again, thank you for your help.

Dave

 

Radio codes only good for the radio if installed but I just cut & pasted it on for TFOI in case you had one on the RK. Usu but not always throws a code so I guess it's the PC getting funky but I have bo experience with those just the SERT. Good luck.

 

Just a quick update on my scoot. I unpluged and repluged every elect. connection on the main wiring harness and did not see anything wrong but went for a short drive later and no problem??? Then on Sunday, went on a long (260 miles) poker run and no problem. Well it seems to be ok.. anyway, thanks again for your help.

Dave