missfire hiccup only at tickover????

[jerry]

my S4 missfires sometimes at tickover its a hiccup that only occurs every 5 seconds or so and only at tickover . Power commander and airscrews make no difference , raising tickover to 1500rpm cures it , bike runs fine at higher revs , and TPS is spot on .And it does it regardless of which fuel i have in it.


any ideas , i dont like mysteries?

jerry

[dunlop0_1]

Is it something that has developed over time or just appeared. The list is endless of things to check but plugs would be my first. Balance the throttle bodies and double check the TPS.:confused:

[DevilBoy]

I have this at low revs. Its like a millisecond where the engine cuts out, and makes a hiccuping noise!

Mine does it when i'm crawling along at low speeds too though. Including when i'm on roundabouts! yikes.

I thought a Power Commander might sort it. But if you have one, I dunno what else it could be!

[jerry]

It only does it at tickover,not when moving, plugs ,balance and TPS are ok,its always been there before PC3 and all mods .

[Scotty]

my favourite suspect would be the coils, (I hate them with a passion)
your sure its not this suspect petrol your using ?

[jerry]

could be the gas but it runs Ok on 95 once the revs rise above 1500rpm

[johnny k]

Have you checked the valve clearences?
I was told that tick over problems are often due to gases getting past the valves.
I have just set mine and replaced the belts, I`m so proud!

regards

JK

[jerry]

Valves recently checked and spot on .

jerry

[jerry]

OK problem seems to be solved , .... probably ,, I downloaded a different PC111 map and tweaked the tickover 5% richer then adjusted the air screws and it seems more stable ,,,raised tickover a bit to 1150rpm also... added bonus it now revs like a nutter bouncing off the redline and rev limiter easily , the new map is a hotter tune.

jerry

[jerry]

I was wrong , the missfire has come back again ,,,even worse now God I hate this bike ..... I am at a complete loss ... It could be the coils but i have swopped them around and it runs OK above 1500rpm ,although not so smooth as before, also they are £300 each here so thats not an option , i wish i had never bought it , impatience should have waited for an M900 .

Dealers here dont do PX so unless i can find a private buyer i am stuck with it.

[ianrjam]

Have you got aftermarket cans fitted? The rhythm you describe could be the pressure dropping and picking up again. I've found that it is easier to set things up to idle and run evenly if you put back the standard cans which produce back pressure and, I've found, allow the engine to heat up in winter as the baffles stop the heat being dumped with the exhaust gases. I had trouble with my M900 until I got everything retuned with the standard cans. You can probably put the nice sounding ones back on in warm summer months. I have a nice cheap M900 (yr 2000) to sell if you get fed up. Ducati proteam in Wimbledon are good at tracing these things. They sorted me out. It took two or three visits but you could phone them to see what they say.
Ian

[jerry]

Have you got aftermarket cans fitted? The rhythm you describe could be the pressure dropping and picking up again. I've found that it is easier to set things up to idle and run evenly if you put back the standard cans which produce back pressure and, I've found, allow the engine to heat up in winter as the baffles stop the heat being dumped with the exhaust gases. I had trouble with my M900 until I got everything retuned with the standard cans. You can probably put the nice sounding ones back on in warm summer months. I have a nice cheap M900 (yr 2000) to sell if you get fed up. Ducati proteam in Wimbledon are good at tracing these things. They sorted me out. It took two or three visits but you could phone them to see what they say.
Ian

The S4 is in Thailand and it never gets less than 80f here so cold weather issues never happen , i may try putting the standard cans on and see what happens but i really want to cure this .

jerry

[jerry]

OK I found a cure , the bleed screw on the rear cylinder injector was leaking air , i changed the O ring and all is now fine , tickover is balanced and constant.

But i have now noticed a bad flat spot in the rev range at 2-3000rpm so am going to richen the PC3 maps on both injectors a few % at atime at those points till the flat spot goes away.
From 1250-2200rpm the bike pulls clean and smooth then it suddenly goes flat before going like a rocket from 3000rpm to the red line , the power is raw and a little harsh but it does fly.

I have to persist because even though i want to sell the bike a buyer may be elusive here in Thailand so i want to get it running a sweetly as possible.:spin:

Jerry