Help! Kindly diagnose my Small Block trouble

[SmithSwede]

Any suggestions welcome.   Bike is currently at MPH in Houston, but I'm still scratching my head.  I love the bike, but am getting weary of the drama.    Triumph Street Triple is tempting me . . .   Save me from temptation. 

2013 V7 Stone.  Bike will usually run ok at higher speed with constant throttle.  For example, ran 15 miles this morning at steady 75 mph with no issues. 

But then it will bog down and sometimes run on 1 cylinder if throttle adjusted open or closed.  Upon stopping, almost impossible to clear intersection at low speed because no power-requires 3-4,000 rpm and much clutch slipping to crawl along at 15 mph.  But sometimes, after that low speed failure, it will suddenly leap forward with full power, running on both cylinders.   The transition is immediate, almost like flicking a kill switch back on. 

Did not throw engine codes from today's misconduct.  Previous stored engine  codes read yesterday by MPH, and all they showed was some O2 sensor codes.  MPH loaded most recent map, re-set TPS.

2 days ago rode for an hour through severe rain storm after a day with bike parked by ocean in Galveston    That day bike was missing as described above, or running on one cylinder only.   MPH found NGK plug cap full of water.   Dried and sealed them, but problem not eliminated.  That episode causes left chrome muffler to turn rusty brown--excess heat I think. 

Originally we thought it was water related.  But it failed again today in dry weather with engine stinking hot. 

I had Eurosports in Fort Worth look at the bike a month ago when it was getting horrible gas mileage and displaying the opposite set of symptoms -- then it was running ok at low speed/throttle openings but not at high speed.  Engine codes showed faulty connection to engine temperature sensors.  They cleaned connectors and problem solved for a month or so, until my ill fated trip to Galveston

This bike also broke down at Kansas rally several months ago.  Running too rich, with black, wet looking spark plugs.  Now both plugs look perfect, a dry greyish tan. 

This bike had its ECU replaced in 2013 when it was 6 months old.  Prior to replacing ECU, bike had similar issues---would run ok at a steady throttle, but would bog and hesitate upon opening past about 1/2 throttle, and would not cruise past 70 mph.

Bike has one of the "hot" voltage regulators, outputting 15.5 volts above 2500 rpm.  I'm wondering if I've cooked something with excess voltage.

Valves are known to be in spec.  Fresh air filter.  I've been through dozens of new spark plugs.  Spark plug caps are the phenolic NGK ones recommended by Pete Roper.   New battery.  I cleaned battery terminals and main negative engine ground terminal a few months ago.   Oil level lowish, just above fill line, no oil in airbox. 

I've removed crank position sensor--no metal swarf or debris.  No longer has EVAP canister.  When gas tank cap removed, no vacuum sound, and removal makes no difference to problem

Problem may be heat related.  Seems to start cold fine, and runs "ok" while cold. 

Cracked coil?

Dodgy ECU?

[Sasquatch Jim]

  Maybe it doesn't like you personally.  Is it anthropomorphic?

[Kev m]

Normally I say to diagnose around the problem as much as possible.

It could be a single sensor/connection.

And my first instinct was to think a secondary spark circuit was grounding.

But it sounds like that happened and was fixed.

Which leaves me with:.


This bike had its ECU replaced in 2013 when it was 6 months old.  Prior to replacing ECU, bike had similar issues---would run ok at a steady throttle, but would bog and hesitate upon opening past about 1/2 throttle, and would not cruise past 70 mph."

Just a swag...

[twowings]

Did anyone check the grounding of the electrical harness and components?

[lucian]

Sounds a lot like a plugged cat con. Likely from the previous rich conditions.

[rodekyll]

I'm guessing fuel delivery.  There's crud in the pump, bad injector solenoids, leaky injectors, bum tank venting (is your carbon canister installed?), low fuel pressure, etc.  Can you hear the pump when it's running? 

I'd pull the injectors and do a volume test -- catch and measure their output and compare them side-to-side and to specs.  Make sure they shut of completely and immediately upon shutting the bike down, and that they have a nice, uniform, conical spray of atomized fuel.  Fuel pressure is optimized between 36psi and 42 psi, with a minimum 26psi needed to form a cone.  I recently measured a pair of big block injectors (not completely efficiently) at 105cc and 107cc in 30sec @36psi. 

Otherwise it's the cam sensor.

Hope this helps

(either is a WAG.  I don't know crap about small blocks)

[guzzisteve]

If MPH can't find fault, and if you like the bike, TRADE IT in for a 6 speed model.

Dump it, try a different one. Simple, no 5 pages of speculation needed !!

[pete roper]

Sounds like the buggered caps and its previous problems have resulted in a buggered cat in one pipe. No point in trying anything until that pipe is replaced as I'm sure that the cat is history and clogged beyond working.

Decent caps, (XD05F's from memory?) new leads and plugs should rule out ignition problems and it has to have at least one pipe.

As I mentioned in another thread I've now had sufficient problems after uploading the latest 'Factory' updates for the MUIG-3 that I've black flagged them and won't be using them unless the owner insists. There are much better options but a map is NOT a magic bullet. It won't fix a mechanical issue and until those are rectified on your bike the problem will recur or continue.

Pete

[Kev m]

Great point Pete on the mechanical, why did I assume they'd already replaced the muffler/cat. But yeah, if the mechanicals aren't up to snuff the electronics mean nothing.

[lucian]

Replace the burnt pipe and if the pulses from exhaust do not feel even to the hand or the original side exhaust smells like sulfur or rotten eggs, replace them both. It's likely that only one side is toast as it seemed to run normally on one side. I think I would be considering an after market exhaust minus the cat's unless you live in a state with a sniff test for inspection. However once the plug caps are addressed the stock pipes should last a very long time with the factory lean fueling. Extended periods at idle will also plug up cat's over time.

[SeanF]

If the over-producing voltage reg/rec hasn't been replaced yet, I would elimate that variable as well.

Maybe someone local to you has a set of stock mufflers for you to try, before leaping in with the big $$ on that particular front.

Best of luck...you'll get this nailed down!   

[sign216]

I've got some guesses, but MPH has a good reputation, so let them look at it first in real life.
Let us know what happens.