Misfire on constant throttle

blueranger said:
With surging though do you not feel the bike want to go faster then slow again, with this it feels like it's going to stall then picks upagain.

Sent from my LT30p using Tapatalk
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Try riding at exactly 30 in third or 40 in fourth. If you are unable to maintain the speeds smoothly, that's the symptoms that I had - surging...
 
If it feels like the bike's cutting the spark, causing jerkiness when on a constant throttle, which clears when you hoof it and returns again once you go back to a constant speed - it could be a couple of things not mentioned yet.
Pull your tank breathers off and remove the filler collar and give everything a damn good clean all the way through. If the pipework's partially blocked, this can cause uneven fuel delivery on a constant throttle, which clears when you open it up and hoof more fuel through the system.
If that doesn't cure it, try sourcing a known good CPU and swap it with yours. If that doesn't cure your woes then you've got to look for wiring shorts/faults and possibly blocked injectors. There are other things to look at as well, but it's all a process of elimination.
 
Mike O said:
Try riding at exactly 30 in third or 40 in fourth. If you are unable to maintain the speeds smoothly, that's the symptoms that I had - surging...
Click to expand...

Oddly a 2.5k in 3rd and 4th it seems okay but 1st feels like a bucking bronco at times.

I have yet to install the Eprom chip to match the zorst so will be interesting to see that that does.
 
Update, finally got around to setting the TPS, managed to get to 369mv then my patience gave up. 371 was just to fiddly for 9pm at night.

Bike has been much smoother most of the time.

What I have noticed is that it seems worse when I'm filtering a riding within a reduced speed range with steady throttle usage.

Still havent installed the EPROM chip worried in case I trash the ECU, probably why I have not done it yet.
 
Eprom chip finally fitted, bike feels much better now. Seems smoother and pick up from 1500-2000 rpm in higher gears is much smoother too.
Will have to see now how well it does on fuel to see if there is any noticible change.

The chip has 99% cured the misfire now, only felt the very occasional slight missed beat, guess its possibly down to it running to too rich.
 
I had this problem last year, it turned out to be split manifold rubber ( yes the left one) . Its worth checking.
 
Get your injectors cleaned and their spray patterns matched up :thumb

It only takes a fraction of a squirt's difference to cause a mismatched firing....and any injector specialist should be able to do it for around 35 quid, ultrasonic clean, spray pattern check and new o ring seals :)
 
SCOTTY said:
I had this problem last year, it turned out to be split manifold rubber ( yes the left one) . Its worth checking.
Click to expand...

It seems you were very close. The previous owner had made his own throttle body test spigot caps and one had fallen off.
Recovered, problem solved.
 
Fanum said:
Get your injectors cleaned and their spray patterns matched up :thumb

It only takes a fraction of a squirt's difference to cause a mismatched firing....and any injector specialist should be able to do it for around 35 quid, ultrasonic clean, spray pattern check and new o ring seals :)
Click to expand...

I take it the injector cleaner stuff just doesn't cut it for cleaning?
When you say the spray pattern matched I take it that its erosion of the nozzles that causes a mis-match. Is that not just an issue for high millage bikes?
 
blueranger said:
I take it the injector cleaner stuff just doesn't cut it for cleaning?
When you say the spray pattern matched I take it that its erosion of the nozzles that causes a mis-match. Is that not just an issue for high millage bikes?
Click to expand...

I don't think it's erosion of nozzles......there are 4 (i think) tiny holes and the head material is either ceramic or some very hard plastic.

It's more likely general crud build up, perhaps from running too low on juice which dredges up tank crap, or the normal shyte that gets added bit by tiny bit when nobbers drop filling nozzles onto forecourts, they get crap on them from dirty filler necks etc etc......SOMETIMES injection cleaner can help, but only if it's a substance that it will dissolve/remove, and that won't include tiny particles of metal, rust, stone, swarf etc etc.

On a proper injector clean, I think they blow them back through, but they certainly clean them out thoroughly and do a spray pattern test to make sure you're spraying a mist rather than dribbling a squirt..

They also renew all the O rings (there are 3 or four on an 1150 injector) and test the resistance of the thing.

I found it made a significant difference to my running, even though it wasn't the answer to the core problem I had.

You can pick up pairs of injectors for under 20 quid on ebay, then you can swap them drekkly to see if there's any improvement, or send either the new second hand pair off or the original pair off for testing/pattern matching....the worst case scenario is that you end up with a spare pair for future use (I've got 3 still here and I sold two sets a while back :blast)
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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