999 burnmarks in throttle body

**safetyfish** · 06 Jun 08, 03:25 PM

Bike is a 999R - 2005 model
ECU is a Corse racing ECU / Racing Air filters
Rest of bike is standard
TPS was reset
Cylinders balanced / CO set at 4.2% / Idle rpm at 1300

Problem: Bike will stall on idle at high temp, or whenever the mood takes it.
Coming into a roundabout this AM the thing died as I changed down in the gears, clutch was pulled in, the rpm dropped to around idle speed, just as I was going into second gear. This is getting annoying apart from dangerous. It feels almost like a sledgehammer is hitting the piston as it dies. It is not the running out of speed kind of dying. It is a violent stop.

Apparently, one thing to check is that butterfly valves opens equally. So I opened the airbox and had a look to see if this has any bearing on the problem. (I can already see trouble with getting that middle throttle cable back in position.)

here is the problem, it would appear that the front cylinder throttle body has seen flame at some point internally.
Am I paranoid or is this normal?
Why would this happen?
How do you fix it if it is a problem?

**Ghost** · 06 Jun 08, 03:41 PM

On my 749 the air bleed screws had 2 big lumps of gump (crap) atached to them. Count the turns in then you can pull them out to check the tapers are clean.

Do not touch the throttle linkage as these are set electronically at Marelli and virtually impossible to get back to the as new position. All this is alledgedly but I've been told it by some eminent Duke peeps Mr Hacket and Baines to name but 2.

**safetyfish** · 06 Jun 08, 04:05 PM

front cylinder airbleed looks OK, bit of carbon but nothing serious.
Vertical cylinder difficult to get out with the fast idle mounting plate in the way. I am very reluctant to touch things around here.......

**Ghost** · 06 Jun 08, 04:08 PM

Its very black mine were nothing like that. The orifice above that just vents into the airbox.

**safetyfish** · 06 Jun 08, 04:15 PM

I have unscrewed the vertical cylinder fast idle jobby. WHat can see of the taper, it looks cleaner than the one in the picture.
I would like to take the screw out completely but the fast idle adjuster mounting plate blocks it. There would appear to be a circlip in there that holds it in position, but I really do not want to mess around with the throttle body assembly.

Any idea why it would backfire on one cylinder only?
Do you think the CORSE ECU has something to do with it? (When I installed it originally, it ran fine. This stalling only started recently)

SF

**Ghost** · 06 Jun 08, 05:31 PM

How many miles on it? Could it be tight tappets?

**safetyfish** · 06 Jun 08, 08:14 PM

Bike has 11500 km on it. (just over 7000 miles)
Picture is the condition of the spark plugs.

SF

**Ghost** · 06 Jun 08, 10:17 PM

Its sort of due for a tappet check but its a pain of a job, all day...ish and even longer if they are tight. As you prob know loose is better on the openers.

**ducati2242** · 07 Jun 08, 04:32 PM

Bike is a 999R - 2005 model
ECU is a Corse racing ECU / Racing Air filters
Rest of bike is standard
TPS was reset
Cylinders balanced / CO set at 4.2% / Idle rpm at 1300

When you say rest of bike is standard what exhaust are you running.The plugs look a bit lean which would happen if you have that ECU / filters without a full system.

**safetyfish** · 08 Jun 08, 03:20 AM

The bike runs a 57 mm asymetrical exhaust.

The general feeling is that the ECU is a mismatch to the rest of the bike.
It needs higher spec cams, Corse exhaust etc to make it perform. Secondly, the bike doesnt constantly live at racetrack speeds, which causes problems when you plod along at 2000rpm.

Either make it a track bike and uprate everything, or realise what it is and treat it accordingly - a consumer edition race machine with lots of compromises to make it go on a normal public street.

So, the old ECU went back in again last night. Pottering around I have been unable to get it to stall again, but that was just going up and down the street and annoying the neighbours. It is high summer here at the moment so testing it properly will take some time.

I have reset TPS / balanced cylinders / set CO at 4% / idle at 1300 rpm / reset TPS again. It is looking good so far with limited testing. I will keep an eye on the condition of the plugs now with the old ECU back in there.

Thanks for feedback, appreciated

SF

**CarsOrBikes** · 08 Jun 08, 07:25 PM

i dont know much about Ducati in particular, but there is a throttle potentiometer right? these don't always sweep clean, and if they cause a problem, at the initial part of the sweep (low revs) you will encounter a 'stop' sensation, as it is not the throttle butterfly opening that determines the fuelling, but voltage from this potentiometer, to the ecu. If the swept track of it is dirty or worn, or poor contact to do with it, you will enjoy the 'real' engine braking effect of a litre twin as it 'returns to idle'. Potentially an 'ouch'!

**Ghost** · 08 Jun 08, 07:54 PM

Quote:

Originally Posted by CarsOrBikes

i dont know much about Ducati in particular, but there is a throttle potentiometer right? these don't always sweep clean, and if they cause a problem, at the initial part of the sweep (low revs) you will encounter a 'stop' sensation, as it is not the throttle butterfly opening that determines the fuelling, but voltage from this potentiometer, to the ecu. If the swept track of it is dirty or worn, or poor contact to do with it, you will enjoy the 'real' engine braking effect of a litre twin as it 'returns to idle'. Potentially an 'ouch'!

These tps are non adjustable and only have to be zeroed out with the DDS or Mathesis. They are quite reliable.

**CarsOrBikes** · 09 Jun 08, 06:09 PM

thats understood, but the sweep can be poor internally, and skip a section of voltage, this will cause an engine to return its revs to idle, or the next good reading along the swept area of the tps if throttle kept open. Am i right in interpreting the problem in that it doesn't cut out, it just loses power very suddenly? But always stays running? See if it always does it at a similar throttle position if it is common enough. (fwiw...Air mass sensors will cause the same. But have no idea if a Ducati has one).

I had a backed out wire on a tps connector once, bloody dangerous.

only my 2p

hope it gets sorted sharpish

**blackie** · 09 Jun 08, 08:47 PM

Quote:

Originally Posted by safetyfish

The bike runs a 57 mm asymetrical exhaust.

The general feeling is that the ECU is a mismatch to the rest of the bike.
It needs higher spec cams, Corse exhaust etc to make it perform. Secondly, the bike doesnt constantly live at racetrack speeds, which causes problems when you plod along at 2000rpm.

Either make it a track bike and uprate everything, or realise what it is and treat it accordingly - a consumer edition race machine with lots of compromises to make it go on a normal public street.

So, the old ECU went back in again last night. Pottering around I have been unable to get it to stall again, but that was just going up and down the street and annoying the neighbours. It is high summer here at the moment so testing it properly will take some time.

I have reset TPS / balanced cylinders / set CO at 4% / idle at 1300 rpm / reset TPS again. It is looking good so far with limited testing. I will keep an eye on the condition of the plugs now with the old ECU back in there.

Thanks for feedback, appreciated

SF

Yer not jokin its a bit hot..Just got back today from Al khor. working at RLOC, should be back next month . If yer need owt let me know & i,ll bring it over

**safetyfish** · 10 Jun 08, 03:53 AM

50 deg Celsius / 60 km/h winds and dust restricting visibillity with sand blown across the highway for the past week. You got to love summers in this place - NOT!!!!
and all I want to do is to take the bike for a short spin to see how she is doing now after I tweaked things around.

Just for clarity,
When the bike idles, it will just stop violently.
It is not a slow cough splutter fart then stop, it is almost like the piston is smacked into a standstill with a 20 pound hammer.
There is burnmarks in the front cylinder throttle body which makes me think the bike is backfiring into the throttle body.
When you dial in the power, it is smooth and intoxicating. There is now power dips, surges or spluttering.
If you snap the throttle open in first, second or third this bike will kill you in an instant.
It is only when she is supposed to be standing still and purring that she acts up.

SF