I have an S4 with a similar issue.
It used to idle at about 1000rpm, but I got the bike's TB resynced and it idled better at 1300rpm. But after a while, when the bike got warmer, 180 degree and up, the idle would start to get rough and it feels like it wants to die. I haven't changed the sparks or the battery lately.
And this problem just appeared one day a couple months ago. I'm probably going to take it back to the shop, but am hoping for a cheaper DIY fix.
Quote from: s4_icyau on May 24, 2008, 09:22:33 AM
I have an S4 with a similar issue.
It used to idle at about 1000rpm, but I got the bike's TB resynced and it idled better at 1300rpm. But after a while, when the bike got warmer, 180 degree and up, the idle would start to get rough and it feels like it wants to die. I haven't changed the sparks or the battery lately.
And this problem just appeared one day a couple months ago. I'm probably going to take it back to the shop, but am hoping for a cheaper DIY fix.
How many miles on your bike?
When were the valves adjusted last?
How many miles from the TB sync until the hot idle issue started?
My s4 will stall frequently until fully warmed up, and idles really really low (~900 rpm).....I always just attrubited it to the cams I am running (DP SPS cams)....The idle is very rough + slow-sounding compared to other monsters I've been around....An s4rs I saw the other day idled like mine does when the fast-idle lever is on all the way!!
-Upping the TPS for a higher idle would help I think....Nothing really to add, just lettin you know that you're not the only one with an s4 that doesn't like to idle.... :-X
My S4 has about 11k miles on it. I dont know when it values were last adjusted. I bought the bike used.
The hot idle issue came up just after a couple hundred miles after the TB sync. I had it looked at in the first place cause the idle was rough all the time. Now after the sync, the idle run smooth until it gets to over 180degrees. It hasn't been too bad of an issue, but one i would like to figure out.
I split this off from the other topic, it was getting a bit confusing...
The spark advance drops way off under around 1000 RPM. This puts less strain on the starter and makes the bike easy to start but it runs like crap if it gets down that low while idling. I'm not sure if that's affecting you.
Look for any obvious vacuum leaks like a charcoal canister hose that popped off. You may also want to check the valve clearances. If your valves are out the TB synch can have limited benefit. Check/change the plugs and air filter but if that doesn't do it you should take it back to the shop. It shouldn't be dropping out of tune a few hundred miles after the synch. Take it back to the shop and explain the problem and how it happens once it is warmed up.
Also, you shouldn't be monkeying with the TPS to get it to idle properly. The TPS gets set and left alone. If it's not idling smoothly there's some other problem.
Scott
My S4 has the same problem. Runs perfectly until it gets hot. Very unstable idle and one cylinder cuts out untill about 2 grand under light throttle. Give it more gas and it's OK. It was just serviced, valves, plugs, TPS, CO adjust, and TB sync. It was ok for a few hundered miles, but is pretty bad now. Just over 7000 miles.
This idle behavior is very much like what I am experiencing with my 620 "Stumble at Idle" thread.
My old S4 was doing the exact same thing. Started happening at 180 degrees and everything.
Nothing I ever tried made any difference, nor was I able to find any other S4 owners who'd found a solution to the problem.
I'll be watching to see if you get it figured out.
My problem turned out to be a coil. I bought a set on Ebay last fall for $50 and decided to give them a try. Now it runs smoother and idles perfectly, even when stuck in traffic. As Mr. Spock would say, Random chance has operated in my favor.
Do you recall if it was the coil on your H or V cyl? When my bike starts this stumble beavior, I can take the plug wire off of the H cyl and the bike starts to idle lower (obviously), then by placing the plug wire back on and taking it off again and then back on, I can immitate the stumble. If I take the plug wire off of the V cyl the bike stalls. I'm thinking that the H cyl coil is going bad. Not firing properly when it gets hot. ???
Good analysis. Swap parts between the cylinders and repeat the experiment: coils, wires, ignition packs if you ahve them. When you find the part that makes the bike stall when you remove the H plug wire but only idles lower when you remove the V (opposite behavior of now) that's the part that's flaky.
Scott
Changed the coil and the spark plug wires. Still stumbles. Damn! Gonna reset the TPS tomorrow.
Anybody ever make any headway with this?
TPS must be spot on 15omv its really critical a low revs and the balance as well.....also tickover must be 1100-1150 minimum any less and it will run bad , also fuel filter must be clean and Iridium plugs help.The S4 does get hot in traffic .
Quote from: jerryz on September 14, 2009, 06:15:23 AM
TPS must be spot on 15omv its really critical a low revs and the balance as well.....also tickover must be 1100-1150 minimum any less and it will run bad , also fuel filter must be clean and Iridium plugs help.The S4 does get hot in traffic .
+1
The proper plugs may be 30 bucks each but it is critical as is the the TPS. I have my idle set at 1200
Quote from: Rameses on September 14, 2009, 01:10:44 AM
Anybody ever make any headway with this?
Mine was TPS all the way.
Wish I had found this thread earlier.
My S4 used to stall out at about 100C (212F). I had it adjusted at the 20K service... and it got worse: starting stalling at 75C (167F), which made low speed cornering damn dangerous.
Last week, I removed the crankcase breather and fitted a KT filter from TPO parts. I was testing the system... and noticed that my bike wasn't stalling anymore... quite happy to go up to and above 212F.
I have no idea why.... ???
I'm having the same issues. Just had the TPS reset about 50 miles ago and it's stallin sitting in traffic at around 1k rpm........ anybody figured this out yet?
Quote from: djrashonal on November 07, 2009, 12:55:27 AM
I'm having the same issues. Just had the TPS reset about 50 miles ago and it's stallin sitting in traffic at around 1k rpm........ anybody figured this out yet?
1K is a little low for a Duc to idle.
can you get the idle speed set to about 1200?
@ djrashonal
Try opening the air bleed screws a 1/4 turn at a time until you get idle up to 1200 or so.
They usually won't idle reliably at 1000.
thanks guys! i'll try that today!
Athough this topic is rather old i want to give it a try and bring it back to life since i experience the same issues.
I also have a S4 with a Termignoni (stock ECU)
There are moments where she idles perfectly at 1100-1200rpm without a hand on the throttle. As soon as she gets hot one of the cylinders starts dying.
Tried the Air Bleed screws today but the idle did not really change. i even had them out by 4 turns. No effect, thus put them back to 2 turns out.
Next thing is reset TPS and syncing the TB.
Does anyone have new suggestions than what was already discussed above?
as has been said before TPS is really reallly critical and set for 1200-1300 rpm ,,, my S4 ticks over sweetly hot or cold but a PC3 and custom maps does help especially in the region from 1000rpm -4000rpm
Quote from: jerryz on August 10, 2013, 01:09:56 AM
as has been said before TPS is really reallly critical and set for 1200-1300 rpm ,,, my S4 ticks over sweetly hot or cold but a PC3 and custom maps does help especially in the region from 1000rpm -4000rpm
Thanks Jerryz, i checked the TPS and the reading said 230mv. Did the adjustment to 150 and will go for a test now. Actually the first test start in the garage did not sound much better than before :( . Idle is at 1100-1200 but it does not seem to change when changing the air bleed screws. i guess i will have to do that electronically.
As for the PC3, i thought about getting one, but i think i will go for the Rexxer now i hope that will do the trick. And of course the TB sync.