S4 running pig-rich

[spuggy]

S4 runs pig-rich around town/short runs - like fuel warning comes on intermittently at 65 miles, goes solid around 70 miles and then takes 10.5 or 11 litres to the "correct" fuel level again. So not a bogus warning like I first thought.. It gets somewhat better mileage on longer runs (did 80 miles yesterday with no warning light yet). Still pretty bad...

Yeh, lifted the tank, cleaned everything up (which seemed to be oil mist or over-generous use of some lubricant spray or other) - no tell-tales from leaks that I can see. Was thinking it was a mobile bomb for a while...

Other clues are:

• inside of termis dark - no heavy soot deposits, but yeh, black.
• eight strokes on low throttle openings/overrun
• sometimes/often "sneezes" back through throttle bodies on re-opening throttle from idle/low throttle openings

My usual strategy for cold starts w/ the manual throttle lever is

• full on for start, let it fast-idle for 30 seconds or so
• move to half-way, ride off
• after 2-3 minutes, knock it all the way off

If I overlook the last step, it just dies when I stop at a roundabout or red light. Which seems weird, as my EFI 2 valvers would have a fast idle - I suspect the lever may do something different/more complicated on the S4? On the 900s it seems to behave purely as a manual throttle...

Bike used to sport a Power Commander, according to a 12 year old email from a PO. If it has one now, damned if I can find it... There's also a couple of unused holes in the tray under the seat; I assumed it was removed.

Plan was to get it to Moto Rapido to check/re-map after I changed the airbox lid to a DP one. I still intend to do this - but I'm really no longer worried about it running lean...

I'm now wondering if perhaps a sensor is going dodgy - eg temperature? - and fooling the EFI into thinking the motor is colder than it is.

Thoughts? Does this suggest anything? I hate to just take it to MR like some doofus...

[Darren69]

Try it with the open airbox lid first as it mightbe that. PCIII on the S4 usually live near or on top of the battery as I think the wires might be too short to reach too far, but who knows, it would be fairly easy to spot one. I usually leave mine on a slight fast idle until the LOW temp on the dash changes (about 40C I think it goes off.) That might be why it's stalling. I have to warm mine up really well as it has a lightened crank and so will stall dead easy if you try to pull away on a cold engine.

I suppose it wouldn't hurt to unplug each of the sensors and give them a clean up with contact cleaner. There are 2 water temp sensors the one on the front cylinder is just for the display, the rear one is for the ECU so maybe start with that. You might even be able to swap the actual sensors if the cleanup doesn't improve things. The air temp sensor is underneath the dash but you probably know that if it is the same for the 2V 'ers

[slob]

what do the plugs look like Andy?
eight stroking makes me think (usually front) stick coil but that’s just guesswork really

[spuggy]

Originally Posted by Darren69

Try it with the open airbox lid first as it mightbe that.

It behaved exactly the same with the factory lid, as I recall. Just hadn't put all the clues together then.

Originally Posted by Darren69

PCIII on the S4 usually live near or on top of the battery as I think the wires might be too short to reach too far, but who knows, it would be fairly easy to spot one.

Right, they don't look exactly tiny - and don't see that many places it could hide...

Originally Posted by Darren69

I usually leave mine on a slight fast idle until the LOW temp on the dash changes (about 40C I think it goes off.) That might be why it's stalling. I have to warm mine up really well as it has a lightened crank and so will stall dead easy if you try to pull away on a cold engine.

Hmm - 2001 got the pre-LCD clocks. No temp display that I'm aware of.

Originally Posted by Darren69

I suppose it wouldn't hurt to unplug each of the sensors and give them a clean up with contact cleaner. There are 2 water temp sensors the one on the front cylinder is just for the display, the rear one is for the ECU so maybe start with that. You might even be able to swap the actual sensors if the cleanup doesn't improve things. The air temp sensor is underneath the dash but you probably know that if it is the same for the 2V 'ers

Ah, never had to mess with the air temp (IAT) sensor on anything; don't know where it is

Good suggestion, thanks!

[spuggy]

Originally Posted by slob

what do the plugs look like Andy?
eight stroking makes me think (usually front) stick coil but that’s just guesswork really

Sigh. Working on amassing Yet Another Tool Collection for reasons I won't bore you all with. Don't have a plug spanner yet.

I haven't even pulled the plugs as it seems to run fine at higher RPMs/wider throttle openings, which is where I'd have expected a dodgy coil pack to show issues first what with with higher pressures/faster response times etc?

[Darren69]

Sorry, Yea mines an '02. You may not even have engine 2 temp sensors then, I guessing? I usually get around 100 miles on a tank before the fuel light starts to come one and off. So it sounds like yours is definitely more thirsty.

[spuggy]

Originally Posted by Darren69

Sorry, Yea mines an '02.

Yeh, no worries - I like the old-school clocks, but the early S4s share a few parts with aircooled 900s - or, like the clocks, parts that look like them, but are actually specific to the S4...

Originally Posted by Darren69

You may not even have engine 2 temp sensors then, I guessing? I usually get around 100 miles on a tank before the fuel light starts to come one and off. So it sounds like yours is definitely more thirsty.

Yeh; my main concern is actually the unpredictable response; would prefer not to be heeled over and open the throttle only to have it spit back/sputter.. It also died at a traffic light yesterday, the instant it turned green. After having idled fine for a while. Re-started at the first compression stroke. Odd.

Certainly has a sensor on the rear pot - but every time I look at the front of the motor, my eyes are invariably drawn instead to the radiator and wondering WTF is up with that

(my end tanks, unlike almost every other S4 I've seen, don't have the screw bosses for the heat shields, and the mounts are assembled weird/wrong; I've wondered if it's an ST2/ST4 or some other random radiator bodged on. Browsing prices for an S4 rad, it dawns on me why someone might do that..)

[Darren69]

Originally Posted by spuggy

Yeh, no worries - I like the old-school clocks, but the early S4s share a few parts with aircooled 900s - or, like the clocks, parts that look like them, but are actually specific to the S4...



Yeh; my main concern is actually the unpredictable response; would prefer not to be heeled over and open the throttle only to have it spit back/sputter.. It also died at a traffic light yesterday, the instant it turned green. After having idled fine for a while. Re-started at the first compression stroke. Odd.

Certainly has a sensor on the rear pot - but every time I look at the front of the motor, my eyes are invariably drawn instead to the radiator and wondering WTF is up with that

(my end tanks, unlike almost every other S4 I've seen, don't have the screw bosses for the heat shields, and the mounts are assembled weird/wrong; I've wondered if it's an ST2/ST4 or some other random radiator bodged on. Browsing prices for an S4 rad, it dawns on me why someone might do that..)

Yea, I noticed that when you first got it. I think it's an ST or similar radiator. I did find someone on ebay selling new S4 rads quite reasonably priced and s/hand ones do occasionally pop up on there too. I'll see if I can find the link for it.

[Mr Gazza]

My first thoughts would be to change the spark plugs, especially as you don't know their mileage.
I generally give my plugs 6000 miles, sometimes they go more if there are no problems.
There is often a definite "going off" around 6000 miles, similar to all the symptoms you describe but not quite so acute.
Plugs might account for some of the thirst if they are missing so many beats per 100? but that's not really running rich as such. I wonder if she's geared down from standard? That would account for the lower MPG unless of course this is a new thing?

Could also possibly be dirty injectors? If you have access to an ultra sound cleaner a quick blast in one of those should do the trick.
The electrical connection to my injectors failed prior to my buying it as a non-runner, and was fun detecting the fault, but once made good has been no trouble during my ownership.

[Darren69]

I'm sure it was bookmarked in my ebay research list but I can't even find how to access that list for some reason.

[Darren69]

https://www.ebay.co.uk/itm/DUCATI-MO...S%7E6&LH_BIN=1

I haven't bought one as I have a spare anyway but seeing the prices for s/hand ones these seem like a very good deal.

[alan s4]

Something clearly not right. I get 120-140 miles before the fuel warning light comes on.

Your fast idle start routine is also different to mine. I use full lever when cold and don't use it at all in the summer (in Scotland!).

Once the engine starts it gets turned down to about a 1/4 for 30 seconds or so and it's then fully off. Even in the depths of winter I've never used it when the bike is actually moving.

Plugs and coil sticks (used from a CBR600R) were changed on mine recently to cure poor running. The front stick was in an atrocious condition due to water ingress. Might be worth a check.

Good luck

PS - I'm running standard airbox with open Termi's and DP race ECU.

[Darren69]

It usually takes mine around 5mins to get up to temp during normal riding temperatures and as it is warming up I knock the fast idle back a little bit at a time to keep it around or as close to 1500rpm when the revs start to rise and so on, so it's not racing away. The LCD temp display is really helpful for this obviously, when it stops flashing we're good to go!

[jerry]

As an S4 owner of 14 years the 1st thing to do is a full TPS reset to 152mv on fully closed throttle with the throttle adjuster srewed open so the stops are resting on open slide reset,, and balance

thats before you try anything else

[Dukedesmo]

Originally Posted by jerry

As an S4 owner of 14 years the 1st thing to do is a full TPS reset to 152mv on fully closed throttle with the throttle adjuster srewed open so the stops are resting on open slide reset,, and balance

thats before you try anything else

Not familiar with the S4 injection system but I have a 916 which is basically the same engine and so probably uses the same setup? and this would definitely be where I would start.

I had a broken screw on the TPS bracket so it was being held with just one and moving about. It ran really badly, popping, misfiring, stalling and wouldn't idle until I repaired and reset it.