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User avatar
By Mr4Square
I'm hoping someone here can help me with a problem with my 2016 C5?

The bike (6000 miles) has a new battery, K&N and free flow exhaust . It has always run well apart from regular fouling of the spark plugs. I tried hotter plugs ( NGK 8,7,6,5, and Iridium ) which just extended the time before the plug fouled. Then I went to NGK 4 and that problem disappeared. Till the mechanic took one look at the 4 and said "oi ... you'll burn a hole in your piston !" So on his recommendation, I bought a matching Power Commander from Hitchcocks.

First up he found a bent pin on the Throttle Body which he reckoned was the root of my plug fouling problem. One new Throttle Body ( because that's the only way to get a new pin) and then on to the dyno tune to fit the Power Commander.

A £1000, 20 hours and two months later, the bike is just awful. He says has done all he can to map the Power Commander to the ECU but can not correct a section of performance at the low end of the throttle. The bike blips and bucks when held at constant low revs . He says it's a problem with the quality of the original ECU and no amount of work on the Power Commander and the dyno has fixed the problem. He also says he has come across poor connections on the electrics, including disconnecting the side stand cut-out while trying to get the Power Commander "tuned.

Today's test run was diabolical. The bike was warm and idling nicely when I collected it. He said apart from the low throttle problem he couldn't tune out, it had been running well.

When I accelerated away the engine immediately started cutting in and out on the run up the road and I almost lost control while turning. He now says there must be electrical problem (none of which were there before fitting the Power Commander.) and suggested he start by investigating the "ignition pick up" ...

The garage is the city's oldest. 50 years in business, experienced with British bikes, Dyno tunning and Power Commanders.

Has anyone seen or heard of these problems or have any suggestions?
-a section of the throttle (low end) that the Power Commander can not "tune"?
- electrical faults after fitting the Power Commander?
- electrical faults that match some of what I have described (sadly that's a pretty large category)

I've seen some very knowledgeable and helpful people here on the Forum and I'm hoping you can help.

Kind regards
User avatar
By Haggis
I have not experienced any off your problems with my 2016 C5 with or without my power commander v fitted.
It does run a little richer but an NGK bpr5es burns clean with no fouling.
Pcv made the small throttle openings much smoother than standard and much stronger right through the rev range.
I use the Hitchcock map for free flowing exhaust and free flow air filter.
I think you need to fix your original running problems before you fit the pcv otherwise you are just adding more complications.
Have you checked the output from the throttle position sensor?
Should be 0.6v at tickover rising up smoothly to around 4v without any jumps or spikes.
User avatar
By Mr4Square
Thanks for your suggestions. Good to hear all went well with your PCV. It can work !
I'll write to Hitchcocks and ask for their PCV map for my setup. (assume that's how I get it)
Just confirming you run NGK bpr5es after you fitted the PCV ?

The bike was performing beautifully before I started this change to PCV, so I'm trying to understand if the problem is PCV or electrical, and if electrical what are some likely causes and diagnostics.

The TPS reading is a good place to start
User avatar
By Haggis
You can see the tps voltage on the power commander software on a laptop.
You can also look at the fuel and ignition tables to see if there is anything that looks out of place.
What map have loaded at the moment?
That may be irrelevant if your dyno guy has altered it.
And yes, I changed to 5 as the 6 was a getting a little sooty from the richer mixture from the pcv.
User avatar
By Mr4Square
I wrote to Hitchcocks as I bought all the parts from them ... here's their reply which was an idea we hadn't thought of ...

"The first thing I would do is just set what we call a zero map. Save a copy of the map which has been created, then fill the entire tables with a “0” and send the map to the PCV. Once this is done, it is effectively leaving the PCV connected into the system but running all of the standard fuelling and ignition settings, if the running issues disappear I would say that the map might be running too rich in certain areas, but once you get to that stage it would be easier to advise along with a copy of the map that has been created. If the problem persists with the zero map, I would say that there is an underlying issue somewhere (else)"

"The only other issue we have experienced and found similar issues is with the relays, the factory ones are not the most reliable setup and it is very common to upgrade these to a proper branded type and is the reason we offer the upgraded type (92059)."

As someone wisely said (roughly) elsewhere on this forum "most carburetor problems are electrical"
User avatar
By Mr4Square
Removed the PCV and have gone back to the original setup.

The fault is still there, so currently fault-finding through all of the inputs (TPS, Engine temp sensor etc ) and the per Hitchcocks suggestion, replacing the Ignition Relay.

Any thoughts on EFI reliability? ( The bike is a Euro 3 so has the first model EFI)
User avatar
By Haggis
There is loads of stuff to check, just takes a bit of time.
Battery must be good condition, 12.8v .
TPS voltage rising smoothly from 0.6v (closed throttle) up to around 4v on full throttle.?
Injector spray correct pattern.?
Triple check every electrical connector.
Might be worth checking the throttle body to cylinder head joints as well.
I have had the spacer fall to pieces
The EFI system is Japanese and very reliable.

User avatar
By Boxerman
Mr4Square wrote:
Sat Jun 18, 2022 4:35 am
Any thoughts on EFI reliability? ( The bike is a Euro 3 so has the first model EFI)
Will a 2016 bike have the first model EFI? mine's a 2009 and the EFI's were introduced in 2008 weren't they? so are you saying that the system wasn't changed until 2017?
Don't know what 'Euro' mine is but it is reliable [after fixing the fuel pressure issue].

User avatar
By Haggis
Euro 3 has rear drum brake.
Euro 4 moved to rear disc with abs and a different ecu.
As far as I know there were no changes to the initial EFI up until Euro 4.
My RE are all euro 3.

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