Minor misfire

echelon · May 21, 2013

Hi All

I was wondering if anyone can help me with an annoying problem that I’ve had for a long while, I seem to have a very minor misfire or stutter just as I pull away at exactly the same point on the rev range it also happens when I’m cruising along at low revs at the same point.

Sometimes the bike will run very smoothly without any stutter for a period then sometimes I will have the annoying stutter back. The bike starts with no problem in fact it is very good at starting and it idles well. I have put new plugs in (Irradium), new air filter, check all the vacuum pipes and manifold for leaks, checked wiring, checked coils you name it and I’ve possibly checked it. I started putting in Shell ultimate and it ran so beautiful I thought I had found the problem but it’s back.

Any ideas?

:banghead

gregorious77 · May 21, 2013

Have you checked and balanced the throttle bodies Vac and CO?

echelon · May 21, 2013

No not yet!

It does seem strange that it only happens sometimes and sometimes it runs really well, if it was a balancing problem it would be there all the time, which leads me to believe it's electrical.

gregorious77 · May 22, 2013

Its ****** ill give you a tenna for it!!

redratbike · May 22, 2013

gregorious77 said:
Its ****** ill give you a tenna for it!!

:biggrin

AR1 · May 22, 2013

I fixed a bike 4 weeks agoo with a similar sounding fault, would suddenly lose a little power and then pick up, he described it as a miss fire, turned out to be the TPS was out by -1

echelon · May 22, 2013

AR1 said:
I fixed a bike 4 weeks agoo with a similar sounding fault, would suddenly lose a little power and then pick up, he described it as a miss fire, turned out to be the TPS was out by -1

Thanks I will try that, think a little trip to the shop is in order

gregorious77 · May 22, 2013

no need to go to a shop for a TPS check.
You only need to join the diag wires (behind right hand panel under seat), switch on ignition and look at the code on the dash.

echelon · May 23, 2013

gregorious77 said:
no need to go to a shop for a TPS check.
You only need to join the diag wires (behind right hand panel under seat), switch on ignition and look at the code on the dash.

I have the Aprilia Tuono Fighter 2003 and the wires are all the same. What wires are they, colour and position behind the panel. What should the reading be in the code and how is it displayed.

Thanks

redratbike · May 23, 2013

Look under the seat 2 plugs that connect together
http://www.apriliaforum.com/forums/attachment.php?attachmentid=173632&stc=1&thumb=1&d=1319504474probably under the mesh panel on yours

gregorious77 · May 23, 2013

Yep what he/\ said.

TPS check.
Wind out fully the fast idle knob
With ignition off connect the diagnostic wires (behind right hand cover under seat)
snap throttle closed a few times to make sure it is fully closed
Turn on ignition
Dash should read zero (0)
If there is a 1 or -1 it needs to be reset to zero.
wires look like this

The TPS is on the end of the Throttle bodies.

Connect two diag wires together
Wind tick over screw right out
Turn key on - dash shows -1
Lift tank
Loosen Torq bolts on TPS
Turn TPS unit until dash reads 0
Tighten Torq bolts and rechecked dash - still 0
Put everything back together
Disconnect diag wires
reset tick over
Test ride

echelon · May 24, 2013

Cheers checked all that and tested, came back as 0, it's ******! you can have it for a tenner

mad biff · May 24, 2013

echelon said:
Cheers checked all that and tested, came back as 0, it's ******! you can have it for a tenner

feed the ****** some red-x in the tank mate and go and kick its **** in for a few miles that should fix it if not i`ll give you 15 quid for it

echelon · May 24, 2013

That's a better offer than Gregourious77, I will try the redex first though and report back.

echelon · May 30, 2013

Just a little update, still no change after putting redex in the bike and giving it a good hammering. What I did notice was that I stalled it the other day when I forgot it was in gear and it jumped like a kangaroo on steroids about 10 feet forward, after that it ran like a dream with no misfires, as sweet as aconked nut. Driving tonight and slowing down for a roundabout it gave a hiccup and conked out, when I restarted it, it was misfiring again. Feck knows what it can be.

gregorious77 · May 30, 2013

gremlins

mikee · May 31, 2013

character.?

echelon · May 31, 2013

gregorious77 said:
gremlins

If I catch one of the fooking gremlins I'm going to cut his balls off

lairylarry · Jun 10, 2013

Just testing a reply - I replied earlier and it said it was being sent for moderation and haven't heard anything since...

lairylarry · Jun 10, 2013

Ok, that worked, so I'll try again.

I've got the same problem. Somewhere betweem 3 & 5k on a constant or slightly open throttle, its a bit stuttery. Mine's always done that when cold, but its previously been fine when up to temp.

I've got Iridium plugs too - a new set, except...I wasn't able to get to the front plug so I couldn't change that at the time. Its only done about 5k miles though so didn't think it would be a problem. However, it might be, so when I get back down to the garage I'll change that too and see if that cures it.

You said you've got new plugs. Did you change the yourself? I've heard of garages not changing the very front plug as its too difficult to get to so could be worth checking it...

Minor misfire

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