Spark plugs

[Karkaliev]

Hi guys, my bike 98 California with 44k miles started misfiring really bad out of nowhere. I just removed the spark plugs and they were all black. Prior to that the bike ran fine. I noticed getting worse mpg lately. The question is what is causing this.
Here’s the photo or the spark plugs
Thank you

[MMRanch]

 

A family of mice move into your air filter ?

 

That really happened to an old Jeep I had years ago !   

[nc43bsa]

Is it fuel injected?

I don't remember if it is or not.

[Karkaliev]

A family of mice move into your air filter ?

 

That really happened to an old Jeep I had years ago !   

I ride it daily and we don’t have mice in Las Vegas. Air filter was pretty clean a few days ago

[Karkaliev]

Is it fuel injected?

I don't remember if it is or not.

It’s fuel injected.
Also the weather was pretty cold last couple of weeks.
Just noticed that the battery was almost dead.
Maybe a combination of everything.

[fotoguzzi]

Inspect the plug leads and caps, are they original?  Does it misfire at all RPM or at a certain point in the rev range?

There is a fuel trim dial on the side of the ECU box. I wouldn’t think it could get out of wack overnight.. don’t mess with it until you know what it does.

[nc43bsa]

If it is FI and the problem started suddenly, I would suspect the temperature sensor circuit, either in the wiring or the sensor itself. 

Most of the time the sensor fails to an open circuit, telling the computer that the temperature is -40°.  You can imagine how much fuel the computer will demand at that temperature.

[Karkaliev]

Inspect the plug leads and caps, are they original?  Does it misfire at all RPM or at a certain point in the rev range?

There is a fuel trim dial on the side of the ECU box. I wouldn’t think it could get out of wack overnight.. don’t mess with it until you know what it does.

It did misfire at all RPM. I replaced the plugs already.
I tried to clean the old ones and the black soot came off right away. It looks like it was not a long term

[guzzisteve]

If the throttle body air bypass screws are full of goo they richen up black just like closing the screws. Check how far unscrewed they are, back them out & clean then put back. Clean passageways too. I clean my throttles every 10Kmi.

[pehayes]

Ah, the '98 is notorious for cold weather enrichment.
The engine temperature sensor is located in the left valve cover.  Its up high, out in the wind.  In cold weather, the sensor never really heats up and thus the ECU always thinks it needs extra fuel for a cold motor.  This is especially important on short rides and slow speeds that don't drive engine heat.

Buy a cheap Honda for short town trips.  Use the Guzzi for serious rides.

You might find some old reports about people building an electronic bypass to fool the ECU into thinking the engine is fully warmed up.

What plugs are you using?  They all get black on one side very quickly.  However, I own two 98 EV's.  Both have 100K miles.  They go for many years without the slightest issue from spark plugs.  Here's what I use.  I have convinced a few other people.  YMMV.

http://www.guzzipower.com/Sparkplug-pehayes.html

You can still find NOS  units on Ebay.

Patrick Hayes
Fremont CA

[pehayes]

Have you removed and cleaned the timing sensor on the flywheel at the right side of the bell housing behind the right cylinder?  The flywheel and clutch are a dry chamber.  The starter motor makes metal-to-metal impact with the flywheel ring gear for starting.  Thus, there is plenty of metallic dust and swarf which can stick on the timing sensor and distort its readings.  Remove, clean, reinstall.

Patrick Hayes
Fremont CA

[LowRyter]

I change the plugs when I adjust the valves.  That's 9k miles for me or 6500 miles, whatever you believe.

[John A]

Have you removed and cleaned the timing sensor on the flywheel at the right side of the bell housing behind the right cylinder?  The flywheel and clutch are a dry chamber.  The starter motor makes metal-to-metal impact with the flywheel ring gear for starting.  Thus, there is plenty of metallic dust and swarf which can stick on the timing sensor and distort its readings.  Remove, clean, reinstall.

Patrick Hayes
Fremont CA

That’s what I suspect, hopefully just some swarf on the pickup throwing things off enough that it goes into “limp home” mode.

[Karkaliev]

Ah, the '98 is notorious for cold weather enrichment.
The engine temperature sensor is located in the left valve cover.  Its up high, out in the wind.  In cold weather, the sensor never really heats up and thus the ECU always thinks it needs extra fuel for a cold motor.  This is especially important on short rides and slow speeds that don't drive engine heat.

Buy a cheap Honda for short town trips.  Use the Guzzi for serious rides.
That might be it. I ride it very short time. About a mile and a half and I’m pretty sure the engine doesn’t warm up at all.
Will try long drive this weekend since the weather will be in the 60s.
Just in case. Does anyone sells new temp sensors?

You might find some old reports about people building an electronic bypass to fool the ECU into thinking the engine is fully warmed up.

What plugs are you using?  They all get black on one side very quickly.  However, I own two 98 EV's.  Both have 100K miles.  They go for many years without the slightest issue from spark plugs.  Here's what I use.  I have convinced a few other people.  YMMV.

http://www.guzzipower.com/Sparkplug-pehayes.html

You can still find NOS  units on Ebay.

Patrick Hayes
Fremont CA

Short trips might be the answer. I do a 3 miles round trip every morning and I’m sure the engine cannot gets warm at all

[Tkelly]

If the above don’t solve the problem,it might be the throttle position sensor.