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+--- Thread: Misfire/stuttering (/showthread.php?tid=83952)
Misfire/stuttering - Pal - 14-01-26
Hi Guys.
I have a problem with my 2014 Fazer 800.
It has suddenly developed a stuttering misfire at low revs with small throttle openings. I commute daily, so this is a lot of my journey in this state.
Whack the throttle open at higher revs and it goes like a scalded cat, clears out completely but back to lower revs and smaller throttle opening, it comes back.
Run a bottle of injector cleaner through it, made no difference
Serviced 5000 miles ago with new plugs, checked them again and gaps had opened up quite a bit. Replaced with new Iridiums, and initially was OK, test ride of 2-3miles was fine.
Bike was off the road over Christmas in a dry garage when I changed the plugs, test ride was in the dry as well. Bike was under a cover, but it rained heavily overnight before my commute. Not sure if this is connected but I thought I'd add for completeness.
Just read about an ECU reset procedure so will try that.
Bike has 38000 miles on it, and as far as I know has never had the shims checked, it is booked in for this next week.
Also I tried to buy a fuel filter but Yamaha doesn't list one as it's part of the pump. Didn't know if the plethora of aftermarket ones could be trusted or even if they would fit this rarer bike.
Any help appreciated.
RE: Misfire/stuttering - Gnasher - 15-01-26
Sounds like a sensor fault could either the sensor or supply to it both electrical or pressure/vacuum. Do you have any codes?
RE: Misfire/stuttering - Pal - 15-01-26
(Yesterday, 03:18 PM)Gnasher Wrote: Sounds like a sensor fault could either the sensor or supply to it both electrical or pressure/vacuum. Do you have any codes?
Thanks for the response
There are no codes, leading me to think it is mechanical rather than electrical.
RE: Misfire/stuttering - Gnasher - 15-01-26
Mechanical issues won't cause sudden misfires. You're going to have to check everything, look for the obvious first, split hoses, vac pipes then start testing sensors.
Page 8-114 of workshop manual
CHECKING THE COOLANT TEMPERATURE SENSOR ..................8-114
CHECKING THE THROTTLE POSITION SENSOR...........................8-115
CHECKING THE SUB-THROTTLE POSITION SENSOR..................8-115
CHECKING THE AIR INDUCTION SYSTEM SOLENOID .................8-116
CHECKING THE ATMOSPHERIC PRESSURE SENSOR.................8-116
CHECKING THE CYLINDER IDENTIFICATION SENSOR ................8-117
CHECKING THE INTAKE AIR PRESSURE SENSOR .......................8-117
CHECKING THE INTAKE AIR TEMPERATURE SENSOR ................8-118
RE: Misfire/stuttering - unfazed - 15-01-26
I agree with gnasher, in thinking its a sensor, but the coils can be an issue also. Corrosion on connectors is another
Unfortunately not all sensors fail completly some like can fail intermittantly.
The Intake air sensor and the Coolant temparature would have the same values when cold and the system uses the difference in these two readings plus the reading from the Mass air flow sensor is what the ECU uses for fueling correctly
I uploaded the service manuals to the FOC-UK owners club on facebook as it was too large to upload to this site
Some of the codes on the FZ8 which may help
11 - No normal signals are received from the cylinder identification sensor when the engine is started or while the vehicle is being driven.
12 - No normal signals are received from the cranshaft position sensor.
13 - Intake air pressure sensor: open or short circuit detected.
14 - Intake air pressure sensor: hose system malfunction (clogged or detached hose.)
15 - Throttle position sensor (for throttle valves): open or short circuit detected. Throttle position sensor (for throttle valves) coupler connection is loose.
17 - EXUP servo motor circuit: open or short circuit detected or loose connection.
18 - EXUP servo motor is stuck.
19 - Open circuit is detected in the input lead from the sidestand switch to the ECU.
20 - When the main switch is turned to "ON", the atmospheric pressure sensor voltage and intake air pressure sensor voltage differ greatly.
21 - Coolant temperature sensor: open or short circuit detected.
22 - Air temperature sensor: open or short circuit detected.
23 - Atmospheric pressure sensor: open or short circuit detected.
24 - No normal signal is received from the o2 sensor.
30 - Latch up detected. No normal signal is received from teh lean angle sensor.
33 - Open circuit detected in the primary lead of the cylinder #1 ignition coil.
34 - Open circuit detected in the primary lead of the cylinder #2 ignition coil.
35 - Open circuit detected in the primary lead of the cylinder #3 ignition coil.
36 - Open circuit detected in the primary lead of the cylinder #4 ignition coil.
39 - Open ciruit detected in a primary injector.
40 - Open circuit detected in a secondary injector.
41 - Lean angle sensor: open or short circuit detected.
42 - No normal signals are received from the speed sensor. - Neutral switch: open or short circuit detected.
43 - Power supply to the injectors and the fuel pump is not normal.
44 - An error is detected while reading or writing on EE-PROM (CO adjustment value).
46 - Power supply is not normal.
50 - Faulty ECU memory. (When this malfunction is detected in teh ECU, the fault code number might not appear on the meter.)
59 - Throttle position sensor (for throttle cable pulley): open or short circuit detected. Throttle position sensor (for throttle cable pulley) coupler connection is loose.
60 - Throttle servo motor: open or short circuit detected. Defective throttle servo motor. Malfunction in ECU (servo motor driving system).
Er-1 - No signals are received from the ECU.
Er-2 - No signals are received from the ECU within the specified duration.
Er-3 - Data from teh ECU cannot be received correctly.
Er-4 - Non-registered data has been received from the meter.