Suddenly...running on one cylinder.

[gbh]

Just installed a 98" kit, nice item!
Proceeded with running in yesterday.
All was great, paid attention to varying the revs, kept an eye on oil temp and all looked great.
Last evening I was riding downhill whilst accelerating. Suddenly it started to miss on one cylinder, catch again, off again. It was kind of an intermittent miss. Then it just plain started running on one.
Distance all of this occured in was only about 350 yards.
After I stopped I found the following.

Rear cylinder not igniting.
Engine light came on
When I pulled plugs and checked them I found BOTH  leads AND plugs showing spark.
Can't find any loose connectors. Fuses look fine visually.
Checked codes and found do1clr to -do10clr   PPU    51502
Thumb over plug holes shows compression so no holed piston or anything horrific like that.
I did the 30 sec switch ignition on/off thing 3 times
Had my bike decided to go into parade mode...whatever that is?
ANY help is greatly appreciated.

[Admiral Akbar]

It could be about anything..

I assume you just RnRed the top end..

Couple of things to think about.

Crap in an injector from contamination at fitting connection.
Loose / broken Injector wire.
A pinched plug wire.
Fouled Plug.

There are probably 10 other easy reasons that could cause the issue.

You need more than a thumb to test cranking pressure.

Max

[gbh]

Thanks Max. This had me really worried because help is thin on the ground where I'm located and its really expensive too!
I was outside all morning thinking it through. I thought, cant hurt to change a few thing to eliminate possibilities.
Change ECM back to OEM...nothing.
Try with and without O2 sensors ...no change
Staring at engine...hmmm got spark, compressions there when doing thumb check (I know, compression gauge would be better but beggars can't be choosers)
Fuel, yes...pretty sure.....to BOTH injectors....?
Reach in with a screwdriver under tank and nudge rear cyl injector....coughs to life 
Well, I know where I'll be looking next.
I know this isn't rocket science to you guys but...to me it sometimes feels that way 
Please feel free to delete. 

[Rodman]

when someone is trying to explain a problem to me and I hear the word
"intermittent" the first thing that always comes to mind is an electrical connection.
Hope that takes some of the rocket science out of it for you.

[bigblock6912]

yr & model may help. sounds like the old broken wire internally on wiring from frame down to injectors, map, tps,etc. also unplug everything you had apart and check for bent pins.

[autoworker]

Check to make sure the plug wire connector is snug on the spark plug.

[koko3052]

Thanks Max. This had me really worried because help is thin on the ground where I'm located and its really expensive too!
I was outside all morning thinking it through. I thought, cant hurt to change a few thing to eliminate possibilities.
Change ECM back to OEM...nothing.
Try with and without O2 sensors ...no change
Staring at engine...hmmm got spark, compressions there when doing thumb check (I know, compression gauge would be better but beggars can't be choosers)
Fuel, yes...pretty sure.....to BOTH injectors....?
Reach in with a screwdriver under tank and nudge rear cyl injector....coughs to life 
Well, I know where I'll be looking next.

I know this isn't rocket science to you guys but...to me it sometimes feels that way 
Please feel free to delete. 

Explain this "nudging the rear cyl"? & it fired up??

[88b]

The plug on the rear injector. Not sure of the years but didn't they have problems with the injector looms being short and wires breaking ?

[gbh]

Thanks for the helpful advice everyone. 
I should have added the bike is a 2001 flstc
It turned out to be the electrical connector on the rear injector. 

Fired up, the bike was running on front cylinder only. I reached under the tank with a long handled screwdriver and wiggled the injector body connectors. The rear cylinder started firing as per normal when I did this. (Koko, sorry I didn't explain this well previously. I hope it makes sense now)

I took the seat and tank off. Applied a little dielectric grease left over from my thundermax install onto the injector connector wires. Put it back together, rode it round town. All is perfect once again!
I usually try to work through problems like this myself or check the HTT forum for related problems but this one had me scratching my head. I hope I haven't wasted people's time.
Cheers everyone. 

[BUBBIE]

Posted by 88b,

Maybe a good IDEA to Still check that for a broken wire...Common...

signed....BUBBIE

[Hossamania]

gbh, did not find it to be a waste of time at all. One more troubleshooting technique to keep in my pea brain.