High Idle, Popping Exhaust

Need some help here. I've had this intermittent problem for several thousand miles. At first it was an annoyance, then a nuisance, then, after I finished my PacNW ride it happened nearly all the time.

Problem:
· High Idle (2-4k rpm) mostly when hot, but a few times when starting from cold
· Inconsistent idle (sometimes low/stalls, usually after a start).
· Exhaust ‘popping’ or ‘coughing’ at idle, sometimes with high idle, sometimes at normal idle
· No issues at normal RPMs/riding
· No real consistency. Sometimes hot, sometimes cold, sometimes after cruising on the freeway, sometimes in the city, sometimes not. Sometimes during a cold start, sometimes not. (Though come to think of it, it does happen after filling up more often than not.)


Things I did (some prior to taking it in for service) with no permanent effect:
· Removed charcoal canister
· Battery disconnect for 12 hours
· Manual reset of TPS (turning ignition on and off 5 times).
· Replaced throttle housing (tab holding it to clipon had broken off the first one)
· Removed/inspected/wiped down RPM timing speed sensor


Problems I found:
1. Airbox seal hadn't been properly seated after the dealer replaced the rear heat shield = meaning unfiltered air was getting into the engine.
2. Oil breather tube had been unplugged from its location on the plastic in the bottom tray (vacuum leak). Assuming this also happened when Ducati Seattle replaced the exhaust.
3. Both the fuel vent lines had been disconnected.

#2 and #1 had me very concerned—basically for at least 3000 miles fresh air was bypassing the filter. This was a particular dealers fault and the heads were replaced.

The popping at idle and the high idle seem to suggest a vacuum leak, but all the vacuum seals check out.

ECU was replaced with the heads, which solved the problem for about 1,000 miles. Now it's back and intermittent. It's driven me and three dealers nuts.

Possible issues I'm thinking:
Sensor that's misreading something and as the ECU 'learns' the symptom doesn't appear until the next start or the next ECU change cycle.

Or

Possibly a component in the system responsible for blipping the throttle as the revs dip is misreading something and causing the issue?

Or O2 sensor?

RTW clock is ticking....

Thanks, guys. All great suggestions. I'll try the ones I can't convince my dealer to do on their own.

O2 Sensors are $268 bucks...hope that's one of the ones they do try.

Phl said:

I will have a pair left over soon.

Lemme know if you need them in exchange for art.

Click to expand...

I think we might be able to arrange something.

Hey Brad--I replaced the throttle tube that contains the TPS. No luck. That was actually one of the first things I did. Second thing was removal of the charcoal canister.

I'm gonna drive the .... out of it and take it into the dealer while it's happening. Hopefully they can put it on the diagnostics right there. If they don't see it on diag it doesn't exist. ....... wish it just threw a code or something.

Base map is a novel idea, though, Phil....can't hurt.

Long story short: dealer has diagnosed that it was the exhaust valve. The cable and bushings in the midpipe were completely worn out. Exhaust valve is moving, cable was stretched and frayed.

I'd disconnected it a while back, so I'm not sure why it being worn out makes a difference, though perhaps it sits at an angle that obstructs the exhaust? No idea until I can see it myself and take a few pics of the jacked up item.

New parts will be in on Friday. Can't wait....should know within a day or two of riding that the ghost in the machine has finally been exorcised!

Take 'er to the dealer. My bike was fixed (though it wasn't the exhaust valve) after I traded it in. I don't know exactly what they did, but apparently it's proven to be a rare issue.