Has anyone got any idea about this problem.
Coming home from work and the bike lost power, felt like it's running on one cylinder. Easing right off on the throttle and it cleared, did it a few times more and then ran fine. OK for about a week (yes I know I should have looked further but not much time at the moment)
Started the same thing again, each time it seems to start after giving the bike max throttle, revving to about 9500 rpm. This time I struggled to get home, every now and then chiming in on both cylinders and then cutting back to one again.
EcmSpy check is giving fault
IAC position too high 34 7 7
Front O2 always lean 0 8 7
I have looked at the connectors to the front and rear coils and contacts look good. The front plug area is pretty filthy from the recent rain and I have sponged this off before looking further.
The IAC connectors and air pipe from the air box look OK - I have not removed the throttle bodies yet.
The bike has only done 26000 miles and was running very well, the valves, looking down the throttle bodies look fine. Oil changes have been done every 2500 miles. Plugs last changed at about 21000 miles and valve clearances checked at the same time.
Anybody got any pointers?

If it's saying the front cylinder is always lean it could be a possible front injector fault ............maybe swap the injectors front to rear if possible and see if it then flags a problem on the rear cylinder ??

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2001 X1 2009 1125CR 2006 Uly X3 2010 Uly a fully Maz'd S1 and a 1991 RS1200 Westwind.

Do the 1125 have one or two IAC? And if it's one only, which cylinder is it attached to? Error messages seem a bit opposed to me.

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"It is often said that before you die your life passes before your eyes. It is in fact true. It's called living."
Terry Pratchett

I havn't removed the throttle bodies yet but the IAC appears to connect to both cylinders.
The injector swap may tell me something and looks easy enough to do so i'll try that next.
I'd like to rule out the front plug also but it probably isn't possible to remove without rotating the engine which i'd hoped not to need to do.
I should have mentioned that i'm sure it is the front cylinder missing as the exhaust feels noticably cooler.
If I run the injector test on EcmSpy they can both be heard pulsing and I have tried cleaning the plugs as the manual says. It does sound as if a spark is jumping the gap.
If I can get the front coil out I'll try another plug in it against an earth to confirm it sparks and potentially rule out the coil.
After that I guess it's remove the throttle bodies for a better look at the IAC.
Thanks for the replies I'll post what I find.

I was going to suggest a coil internal breakdown. May not show up until hot or under load.

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08 Specialized Langster

Thought someone had done a thread on here explaining how to change the front plug without a rotation, it involved the removal of various gubbins and no doubt skinned knuckles .

Failing front plug would be rich all the time not lean???

Try swapping injectors.

IAC connects to both inlet stubs.

And yes you can remove the front plug in the frame,it's just a bit scary the first time as you need to bend the coil a little to get it out.Then it's just a case of the right combo of extension pieces to get your ratchet in to undo the plug.Remove and refit plug using a short length of rubber hose.

IAC could be too high because it's trying to maintain idle with only one cylinder running properly????

What do the MAPf/r compare like?

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Nige...1125d 9.43@140mph

If i remember right from when i read my manual when i bought the bike you can't test plugs if you have no plugs fitted because it uses the slowing down of the crank due to compression to keep a track of the engine position ...... so no plugs in equals a freely rotating engine

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2001 X1 2009 1125CR 2006 Uly X3 2010 Uly a fully Maz'd S1 and a 1991 RS1200 Westwind.

You use the plug clearing function.Ignition off,hold wot then turn on.The ecm sparks both plugs multiple times.

Vern, where abouts are you? and what were the valve clearances at 21,000? After another 5000 they could have gone tight? I'm seeing 5thou inlet and 7thou exhaust on 16,000 and 18,000 engines.

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Nige...1125d 9.43@140mph

Thanks for the replies, lots of good direction.
So far I have removed the throttle bodies because I was concerned about a lot of grit around the injector housings. Removed the injectors, cleaned in an ultrasonic bath and although they looked OK a lot of "rubbish" appeared to float out.
Removed rear coil and with plug still in engine tried firing a spare plug. Using the plug clearing technique in the manual - lots of spark action - very impressive.
Used EcmSpy to do the plug test check and rear plug firing fine.
Tried to remove the front coil but I could not see any way of doing it without damaging the coil, reading recent posts I might have another try BUT read on. Front plug sounds like it is firing on both above tests.
Put injectors back in place after cleaning but have swapped previous front and rear injectors as recommended previously. Laid throttle body to one side, but with TPS connected and IAC removed but electrically connected.
Using EcmSpy I ran the fuel pump and no leaks or dribbling through the injectors evident. Ran the injector test a few times running the pump up intermittently. Injectors appear to be OK (Cleared through the remains of water from the ultrasonic clean at the same time. Suprising how much was in there even though I had blown them with an air line. Sucked out the fuel with a vacuum!
Watching the IAC with the ignition switched on it cycles through open, closed, open. Tried blowing through it by mouth while it actuated and it appears to shut off OK.
I,m going to put things back together now and give it a try. I'm tempted to try and swap the coils but A: I've switched the injectors already so don't want to do two things at once and B: I think if what I have done already doesn't work I'm going to have to rotate the engine anyway to do the valve clearance checks. (Done last time by Black Bear so I don't have the figures but I have no doubt that it was done "to spec".) So I may as well do the coil swap then. At least I'll be able to get at the rear one if it is the problem afterwards and I am worried about breaking it.
Thanks for all the help.

Started bike up (No airbox or filter fitted) and running fine for about 3 minutes then cut onto one cylinder. Revved the bike a few times and it came in on two cylinders and running on sidestand for about 10 minutes all is OK.
What I did notice is that on EcmSpy when it was only firing on one cylinder the Front EGO Correction was at 175 and stayed there until the second cylinder cut back in then it went back to approx 87%
Hopefully there is an included file showing readings when bike is running ok,
I'm inclined to think it may be still plug / coil related but could the lambda sensor cause this or is it reflecting the fault.
Any ideas before I try swapping plug and coils?

Can you do a screenshot with it running badly for the same condition?

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08 Specialized Langster

If the front cylinder is missing,remember the exhaust gas is measured with an oxygen sensor. If the ignition fails on some strokes then even though there may be unburnt fuel (which the o2 sensor does not see) there is still more oxygen so the ecu sees this as lean and adjusts for more fuel.
So it may be missing on front cylinder.

Thanks all for the replies.
Work unfortunately now intervenes. I will continue wednesday.
I will get a screenshot if / when it misbehaves but Sod's law, so far it's OK!
I think I'm going to try "bending" the front coil as suggested before rotating the engine!

Don't worry you're not bending the important bit when doing this.

I have spares if you need one to try,or a testbike to check yours on,thats why I asked where you were/live.

As for O2 Colin's probably right,with individual sensors it will only see the unused oxygen.

But when i had a dodgy coil connection it came up on the ic,saved me hours of messing about to find the fault.

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Nige...1125d 9.43@140mph