Ducati.org forum banner
1 - 2 of 2 Posts

· Registered
Joined
·
6 Posts
Discussion Starter · #1 ·
This has me and my friends at a loss. I have a 2003 999 with 40,680 miles on it and up until about 30 miles ago it ran reliably and strong. Out of the blue the idle dropped from 1,200 rpm to 1,000 and would skip a beat or, sometimes, quit running altogether. Thinking that the injectors might be getting gummed up I put some cleaner in with the gas but over the course of about 15 miles or so it got worse. I hooked up the ELM / M5X app and checked to see if I had any fault codes. Yes, yes I did. Some were listed just once while others more than once. Everything from Crank Angle Senor to MAP Sensor to Wheel Speed Sensor to Air Intake Circuit Malfunction to Ignition Coil Malfunction to Cooling Fan Loss of Signal to Immobilizer Invalid Signal and one that is ever-so-helpful, "U165B: Unknown". SMH. I cleared those codes then disconnected the battery, joined the two battery cables together for while to reset the electronics then reconnected the battery. I started the bike up and no codes appeared. No, I did not get my hopes up.

As the engine ran okay once running above idle I opened the airbox and adjusted the idle speed screw back to 1,200 rpm which initially helped a little though the engine did skip a beat every now and then. Hoping to aid the injector cleaner in doing its job I took it out for what we called in my long-past youth an "Italian Tune-up". That is, running the engine at high rpms for sustained periods of time and it ran reasonably well until I did my first WOT blast and got up to around 8,000 rpm and POW! The backfire was LOUD and the engine noticeably skipped a beat. This was going from not good to not good at all!

I read a forum comment that a faulty Crank Angle Sensor can lead to other codes so I changed it with no improvement. In fact, I took it for a short, very short as it turned out, test ride and when I pulled out into traffic it died leaving me at the mercy of on-coming traffic. Fortunately, I got it re-started and out of harm's way quickly then headed back home counting my blessings the entire way.

Since then, I have changed the Speed Sensor, installed a replacement Ignition Coil first on the horizontal cylinder then onto the vertical cylinder and soldered a new Absolute Pressure Sensor onto the instrument panel circuit board. None of these changes showed even a trace of improvement.

In a nutshell, this is what the engine is doing now: When it is started up cold, which it does just fine, it will idle nice and smooth. (I would like to rev it at this time to see if it would backfire at higher rpms but we all know to NEVER rev a cold Ducati, right?) I keep an eye on the engine temperature as it warms up and shortly after the temp gauge stops flashing and steadies around 140 - 145 degrees F the idles becomes unsteady and, more often than not, the engine just shut itself off. It will restart just fine and continue to run rough. If I raise the rpms up somewhere between 3,000 and, say, 5,000, and try to hold it there, it's a lost cause.....the engine will either increase or decrease in speed and refuse to hold a steady setting. If I rev the engine hard from idle it will rapidly gain rpms without a stumble but it will backfire most often around 8,500, sometimes before that speed and sometimes after and always loudly with a huge stumble in the engine.

The plugs, timing belts and fuel filter were changed within the past 100 miles and the plugs have excellent color, light brown with zero signs of oil or excess gasoline, they are dry and the gaps are correct at .030" / .76mm. The voltage display on the dash shows 14.1 at idle and 14.3 when cruising. The battery is a Shorai Lithium and it will reach a full charge in less than a couple of minutes according to its charger even after a long ride.

I am out of ideas and would appreciate any and all opinions from the Forum members. Thank you all in advance.

Rrudytoo
Simpsonville, SC

Tire Wheel Fuel tank Plant Automotive lighting
 

· Registered
Joined
·
6 Posts
Discussion Starter · #3 ·
Thank you for your thoughts, Bott. Right now, replacing the ECU is being considered due to the rash of various and sometimes unrelated fault codes. I will keep updating as troubleshooting continues.

Rrudytoo Tire Wheel Fuel tank Plant Vehicle
 
1 - 2 of 2 Posts
Top