Mis-Firing...

[GregD-UK]

Hi all,

Since I put my bike back together I have a small electrical problem. Namely, the starter relay diode. The wiring was abit amiss and "Pierre" with my limited knowledge managed to sort it. However, whilst on a ride out a mis-fire was happening, especially whilst throttling off, or on low revs. It became more apparent when the bike got hot around 77-80 degrees. A couple of times it would stall whilst at a junction/traffic light. I changed the ECU and no resolution. Checked my plugs and leads, all OK. I reverted back to my original fuel filter, bought a new one off flee-bay. This worked for a couple of days. Then, on the way home today, a small mis-fire and two stall's whilst stationary

Checked my fuel pressure it was running around 3.3Bar, but, this was checked with a foot-pump gauge, so not terribly accurate. Know it should be around 4.5Bar when under heavy accelleration. I can only summise for now that maybe the fuel is a contributing factor?

Anyone, got any idea's....

[D-Rider]

How are the plug caps?
How are the coils?

The temperature related bit adds to my suspicion of those.

[fatboy]

98% of petrol engine mis fires are electrical.
Sounds like it could be coils, as they get a bit eldery, they break down when hot, work again when cool.
If you know the plugs to be good, try a spare 'slave' plug in the easiest to reach plug cap next time it mis fires

[GregD-UK]

Hi all,

OK FB, will try that thanks....

[GregD-UK]

Hi all,

have put my original coils and aprilia HT leads back in, the magnecour one's seem rather flimsey, to be honest. Rang that AP place in tamworth, told would sort out over the phone, as he didn't want me to go to glasgow (On one of his jolly's around the UK). Rang back, didn't even want to speak to me, very disappointing, obviously doesn't like awkward jobs.

Going to a dyno guy who has a fuchs dyno and he is going to balance my TB's. Hopefully find the problem. Went on the AF1 website and found quite a common problem in hot weather in the states when aprilia's won't start or stall due to heat. Obviously, we don't get really hot weather over the year, except as we speak So, the heat problem doesn't rear it's head in the UK. AP weren't even aware of the issue.....

Let you all know what transpires manana

[Aladinsaneuk]

Do you have an immobiliser / alarm?

Check the bridge on the left under the rear cowl

Check the right hand engine starter switch gear

Check inside the right snorkel inlet

[HisNibbs]

I posted similar symptoms recently and one of the Falco massive pointed me to some very thin sensor wires between the cylinder heads on the left hand side under the air box. These had the insulation worn away.

Was really hard to spot even looking for the specific problem but a little wrap with insulating tape and a cable tie to keep them from doing it again, seems to have done the trick.

[GregD-UK]

Hi all,

Got back from an eventful ride down to north yorkshire to the dyno centre in Bellerby. Missed acouple of times on the way down and whilst I navigated through richmond it stalled on me and took a spell to start again Luckily I travelled early to miss heavy traffic.

Got there and told simon (Dyno Guy) what my symptoms were. We put it on the dyno and the TB's were a little out not much, balanced them. Set away to check the fuelling (which I hoped was the problem). He slightly riched the lower end of the map, whilst on there it didn't miss a heart beat

He was looking at me with a bemused look, so I told him to go for a ride. 10mins later, he rolled back into the courtyard. Sure enough, he said is was missing just on neutral throttle and when slowing down. Pulled ok when on the throttle. My sherlock holmes deductive reasoning, leads me to believe, that whilst riding either I move in the seat (Possible wire or wires under seat catching!) or there is a wire that moves around the engine and might be baired out. Just like Mr. Hisnibbs has just suggested

So, head torch at the ready and try and track ALL my wires under the tank and around the engine.... Will do it this w/end and see what happens. Scared to do a good ride incase I stall on a bend or roundabout. Thanks for the input men

Keep you informed, as always.

[GregD-UK]

Hi all,

Well, my sincere thanks to Keith(Hisnibbs) for pointing me in the right direction. Found said sensor on the left side under the TB's and the connector plug just on the wire was bared to the copper. Coming back into town off a ride must settle the wire and ground out on the engine block, causing my bike to stall

Cleaned the connection and applied good electrical tape and some shrink wrap....

Went for a ride and all is well with the world again

Cheers men.

P.S. If your bike starts to stall or mis-fire check under the TB's

[D-Rider]

That's good news !

[HisNibbs]

That's two correct guesses in a week. Maybe time to play the Lottery...

[fatboy]

Think that one has caused a few some headaches, glad tou found it !

[scottyni]

think i need do same myself!

bodies synched and valves ok plugs changed last year so wirewatch for me!