lack of power, surging, cHE error

[Miki]

Hi folks, I’m oput of ideas how to bite the problem and need help from people smarter than me.
It’s Hyosung GT650 2012 (EFI i believe. 2 sloted ECU).

I bought it with disabled rpm meter and Fi check lamp lighting, but it worked fine. A bit Jerky, but fine.
Now unfortunately it lacks power, especially at starting from a stop, and at higher RPM. When not operating throtle it also sometimes slows down and gains speed rapidly.

i tried shorting the dealer mode coupler with a “special tool” which was a piece of wire, but all it shows is cHE.

I checked TP sensor – seems to be working fine, changed spark plugs, o2 sensor, checked the pick-up coil – resistance and conductivity are fine.

I’m down to try any idea you have, I just want the nightmare to end.

[♠️ MARCEL]

Hey , don’t worry im sure we will get to the bottom of it, the more you describe the situation or keep updating us.

Dealer Mode =  Did you follow the service manual exactly , if you ECU is “DELPHI”  get the “D-Spec”  or 2012 onwards manuals from this forum ,  if it is DAEWOO ECU < get 2009-2011)

If it is DELPHI = FI light will come on when you switch on bike, but it must go away after it is running and idling.

If it is DELPHI = Fi light will not go away even after 5 minutes idling , then remove battery , disconnect ECU carefully! – Wait overnight , then put everything together,  trick the ECU on more time with dealer switch following the manual to get error code , and tell us what it is.

If it keeps saying CHE all the time,  the manual says there is communication error between “Kill Switch handebar + ECU + Harness”  , so make sure the harness is no damage and the connectors for the ECU are delicate , so check there is no broken pins.

Take picture of ECU and show us , if you are not sure which ECU you have.

Other parts for you to investigate:

• ISCV   (Idle Speed Solenoid Valve Control)
• Airbox Air Sensor
• Engine Temperature Sensor
• Radiator Temperature Sensor
• Radiator ThermoStat (if it is funny, ECU will be confused if cylinder is hot or not because of mixed temperature coolant flowing inside cylinders) (It can make ECU panic or switch bike off automatically)
• Spark Plug HT Caps  (Very common) (Replace if possible with NGK ones as they rarely failt)
• Ignition coils for Sparking = Test Primary & Secondary Resistance Ohms with meter and compare with manual

Stator can act funny, so keep this in mind , even if it works , when it gets hot, then problems start.  So be ready to replace Stator , if it is needed but check the list above ^ first.

• Regulator = It must be 14v idling and 14.5v max at 5,000 rpm
  if regulator is saying 12.x volts in any revs = replace it immediately with Shingden like this one
  Do NOT use aliexpress parts , as EFi Hyosung bikes a very hungry for electric juice, chinese parts will fail quickly and burn expensive ECU.
  Sometimes it can be very hard to find a good ECU

If everything is 100% checked and confirmed OK?   = We may need to buy another ECU.  But i hope not.

// Meditation doesn't mean you have to sit still....

[Miki]

Thank you so much for your help.

I took off the battery and ECU for as whole day, connected again, the FI and cHE still stand. Here’s the ECU.

I checked the following:

-IAT Intake air temp
-IAP Intake Air pressure
-WT Water temp
-TP Throtle posistion – it was slightly off but not much. I adjusted it nevertheless.

Can’t check the termostat without warming up the engine, and i alrteady took off the tank and air filter.

Regulator gives 14,2V at Idle and 14,5 at higher rpm

But the ISCV behaves strangely. The instruction says the valve should extend at switch ON, but my only twitches a bit at most. Tried to make it move for a few minutes, succeded only once.

Couldn’t recreate that event.

I couldn’t unplug the injector couplers to check them, no idea what kind iof magic bounds them.
after discovering the ISCV issue I didn’t inspect ignition coils. Will do when i find time again soon.

You think ISCV can cause the problems?

[♠️ MARCEL]

Hey ,
ISCV issues can cause issues yes ,  is it possible to get a used one locally and be sure ?

It sounds very stupid but follow me;

• Stator = Replace it.   (The timing sensor could be playing havoc when it is hot , which is tripping the ECU)
• Regulator = Keep a very close eye on it  (or upgrade it) (no cheap knock offs as the 650 will set cheap ones on fire quickly)
• Stator Plugs = Use contact cleaner and make sure harness is good.
• Plugs for ECU = Contacts cleaned and make sure it is firmly connected  (without too much stress as pins are very small)

If it says  “Fi  (F Eye) ”  not   “F1  (F ONE)”   ===> F Eye means injectors have problems or clean them hard …. and remove fuel pump (very carefully as it is very expensive) and make sure it is not clogged up    ===== F Eye is fuel injection system , so commonly it is Injectors and Fuel Pumps

It could explain Jerky / Surging behavior on your bike cause by  possibly  “Stator”  ,  Harness Plugs dirty  ,  Clogged or Damaged Fuel Pump ,  Dirty or Bad Injectors

// Meditation doesn't mean you have to sit still....

[Miki]

Injectors were actually cleaned by the only mechanic in my city who was brave enough to touch Hyosung (and failed) so at least that’s off the list.

I will get myself a contact cleaner, and look for a new stator tho finding a replacement part here is not easy.

Thank you for advices. I will update the post when I make any progress.

God bless you kind man.

[♠️ MARCEL]

Miki wrote:

Injectors were actually cleaned by the only mechanic in my city who was brave enough to touch Hyosung (and failed) so at least that’s off the list. I will get myself a contact cleaner, and look for a new stator tho finding a replacement part here is not easy. Thank you for advices. I will update the post when I make any progress. God bless you kind man.

Quote

Send us an email if you need it , as we sell stators on our shop.

// Meditation doesn't mean you have to sit still....

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