S4 running pig-rich

spuggy · 21-09-2020, 10:23 AM

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...

21-09-2020, 10:23 AM	#1
spuggy Registered User Join Date: Apr 2016 Location: Farnborough Bike: M900sie Posts: 171	S4 running pig-rich 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...