Cylinder dropping

[Will s]

Working backwards on a issue that started as engine cut mid throttle and progressed to a puff of smoke on start and throttle blip just after .
  Have replaced teabag , fuel pump , reg and plugs . The teabag and return bowl were pretty dirty . The bypass external filter was OK.
One issue I can see is the spark caps are sparking from the side of the caps halfway up when I placed them on the side of the motor when trying find which cylinder is missing at idle . No4 is the miss . I can pull No1and the idle becomes lumpy . No4 on , bike idles  but you can here the miss at the pipe but not lumpy .
This brings me to the next situation.  With 4 connected  I get a puff of smoke at start and then throttling on from idle . With 4 disconnected I don't get this . Fuelling? Throttle body sync ?
Also are there any aftermarket plug caps that suit ?
Thanks

[seth]

If your teabag was very dirty it might be a dirty or partly blocked injector .
Try swopping injectors between a couple of different cylinders and see if the problem moves

[Will s]

Just a update . Balanced throttle bodies , no change to miss but idles nicer . Compression test all cylinders are close enough. Looks like i will get the injectors professionally cleaned next . Still need to work out what top do about the coil and spark plug cap situation. Number 1 wire is stiff and hard back to where the sheath starts the rest are soft and flexible. Coils test up ok but unless i can replace the plug wire i might be up for new coils and caps . Is their an equivalent to the Taylor leads available in Australia ? Found coils locally just not leads  with a cap long enough to reuse the rubber cover , like pictured, that stops crap getting down the plug holes.

[Eric GSX1400K3]

I reckon you're one the money with a faulty ht lead. Have you tried swapping the lead to another to see if the problem moves?

[Hooli]

I believe if you pull hard enough the leads come out the coils. I know they do at the plug cap end.

[Will s]

I reckon you're one the money with a faulty ht lead. Have you tried swapping the lead to another to see if the problem moves?

Strangely the miss is on 4 with the good lead . 1 with the dodgy lead fires ok .Just eliminating replacing stuff as I find it . Seems like spark is ok even with the couple things that aren't 100% . Looking more like a fuel or throttle body issue on 4

.

I believe if you pull hard enough the leads come out the coils. I know they do at the plug cap end.

Wish I had spare I would give it a go . Read on a old suzuki forum were someone had got one off and replaced . Sealing it back up was a bit tricky .

[gsxbarmy]

Are the coil brackets ok? I vaguely remember some years back someone (on the old forum I think) who had a similar problem and found a cracked bracket which was giving a poor earth. May be worth checking and even if no cracked bracket, just generally cleaning up around the bracket and where it bolts to the frame. Stranger things and all that.

Also - if the caps swap ok - have you tried just doing that between coils?

Finally - have you checked you don't have dry joints on the connectors to the coil packs. Could be a joint going off, may be worth checking resistance etc.

Just odd thoughts, as this seems a bit of an oddball problem

[Will s]

Are the coil brackets ok? I vaguely remember some years back someone (on the old forum I think) who had a similar problem and found a cracked bracket which was giving a poor earth. May be worth checking and even if no cracked bracket, just generally cleaning up around the bracket and where it bolts to the frame. Stranger things and all that.

Also - if the caps swap ok - have you tried just doing that between coils?

Finally - have you checked you don't have dry joints on the connectors to the coil packs. Could be a joint going off, may be worth checking resistance etc.

Just odd thoughts, as this seems a bit of an oddball problem

Brackets are good . Coils seem to be doing what they need to even with a stiff lead.
Might be getting closer number 4 port on the fuel rail, looks like degrading o ring and gunk .
Backyard injector tester shows 4 not having the same spray pattern as 1 , the only two I tested .
Be calling the mobile injector mob tomorrow.

[Will s]

Got me stumped . Injectors cleaned . Smoother idle  but still got number 4 dropping . Pulling number 4 plug lead makes no difference to idle . Swapped lead from 1 to 4 no difference.  So to date replaced fuel pump,reg , teabag, back flushed pump housing  . Cleaned fuel rail and injectors . New plugs . Balanced throttle bodies and reset tps .Pairs removed .

[Hooli]

You might need to take the TBs off to do it, but I'd be thinking of checking the secondary throttles. If they are well out of adjustment it could be No4 is totally shutting & knocking that cylinder out at low revs. As you rev the bike up the ECU will open the secondaries too & the cylinder will cut in.

As for your plug caps, the connector for the plug is about halfway up the plastic body internally. So a spark jumping from that area makes sense to me as it's the shortest route to ground.

[Will s]

Think I have got it close to being sorted. Looks like my elcheapo carb balancers had a gauge out of the 4 not reading right.  Using 2 of the 4 guages across the cylinders I rebalanced and 4 came on . Still need to reset tps and bolt a few other things back up before I can take it for a run . Had just ordered bits prior to getting it sorted to do a cop conversion  as it worked out cheaper than replacing the coils doh .
Into the spares bin