korider.com | Hyosung Motorcycle Owners Forum

korider.com | Hyosung Motorcycle Owners Forum

  • March 20, 2019, 02:34:27 PM
  • Welcome, Guest
Please login or register.

Login with username, password and session length
Advanced search

News:

Welcome to Korider.com!

Pages: [1]

Author Topic: Erratic Engine Behaviour when Warm  (Read 229 times)

xuraax

  • Learner rider
  • **
  • Offline Offline
  • Posts: 41
Erratic Engine Behaviour when Warm
« on: November 16, 2018, 06:35:43 PM »

After facing several FI errors around the O2 sensors some time back which now seems to have cleared (or at least no FI error is being generated) I am facing another issue.

My bike is a 2013 GT250 with a Delphi ECU.

The bike starts properly and easily and seems to run perfectly for about 15 minutes after which it starts missing and jerking as the second cylinder kicks in. To me it seems like it sometimes looses power on one cylinder but not continuously. No FI error is displayed.

Recently the outside temperature where I live has dropped by about 10C and I have note that this problem appears later say after about 30 mins riding which seems to confirm that it is indeed a temperature related issue.

I have replaced the plugs and the plug connectors with NGK parts. I also found that the side stand switch had developed a high resistance of about 500 ohms when it should be zero. Although this did not seem to cause me any issues I replaced it with a new one but my still problem persists.

I am now looking into the ignition coils. Whilst having this problem the temperature of both coils feels about the same to the touch.

I would like to buy a coil and replace one at a time but unfortunately my local dealer does not have any in stock. Both coils are marked Delphi 28198992 2J26B.

On the internet I am able to source Delphi coils having the same first number but the second number is always different. Any idea what this number implies?
Incidentally the cold resistance of both coils is within the tolerance of what is specified in the manual.

Any suggestions please?


Logged

Register and log in and the Ads below will be gone! :D


xuraax

  • Learner rider
  • **
  • Offline Offline
  • Posts: 41
Re: Erratic Engine Behaviour when Warm
« Reply #1 on: December 14, 2018, 07:12:27 PM »

I am still facing this problem without any apparent solution to date.

I have now removed the fuel injectors and on inspection I have found that the rear injector housing is totally clean.
On the contrary, just beneath the front injector I found a fair amount of dirt which looked like paste with particles in it.
I honestly do not know where this dirt came from since this bike has not even done 12000km.
I also do not understand why dirt was found in the front carburetor but not the rear since they share the same fuel pipe.
Also, when I remove the O2 sensors, the rear one is always clean while the front one builds up carbon on the surface which, in the past, has generated an O2 sensor error.

In any case I am in the process of cleaning the injectors. Can I also install a fuel filter after the fuel pump to avoid dirt getting to the injectors? Is there in fact a fuel filter incorporated in the pump inside the fuel tank?

This is a 2013 EFI bike equipped with Delphi parts.
Logged

umop-ǝpisdn

  • Global Moderator
  • Forum Addict
  • *****
  • Offline Offline
  • Posts: 7535
Re: Erratic Engine Behaviour when Warm
« Reply #2 on: December 15, 2018, 01:40:32 AM »

..and its temperature related?  :-\

The sediment is easy enough to explain. Old fuel absorbs some water which ever so slightly rusts the inside of the tank.
Logged
I used to be a sensitive, new age guy, but times have changed and now I am more of a caring, understanding, ninties type.

xuraax

  • Learner rider
  • **
  • Offline Offline
  • Posts: 41
Re: Erratic Engine Behaviour when Warm
« Reply #3 on: December 15, 2018, 07:18:51 AM »

..and its temperature related?  :-\


The reason that initially I related this issue with temperature is because the problem definitely gets worse after the bike has been running for several minutes.

Maybe the issue only gets noticeable with time!!! I don't know enough about EFI systems but it could be that initially the ECU tries to force more petrol until the engine gets warm by ignoring the input from the O2 sensors. When the engine warms up, the ECU may be trying to reduce the fuel flow to run the engine efficiently but does not know that it has a partially fouled up injector at the end.

Again this is a supposition which I need to test out.

What is certain is that I do have soot on the front O2 sensor and there was muck in the carb just beyond where the front injector sits.

Another thing that I noted is that when I start the engine from  cold and I put my hands on the 2 exhaust pipes at the cylinder exit the rear pipe gets unbearably hot to the touch far earlier than the front one, probably indicating a more efficient burn.

Returning back to my earlier question,  "how do I get to my fuel filter which I presume is inside the tank?"

I have a tank full of petrol which I need to empty without making too much of a mess. I cannot turn the tank upside down since fuel will leak out probable from the fuel cap air vent.
Logged

spit051261

  • Grinding the pipes
  • *****
  • Offline Offline
  • Posts: 1416
Re: Erratic Engine Behaviour when Warm
« Reply #4 on: December 15, 2018, 09:11:00 AM »

Just put your tank flat, safely on wood or the like filler at top.
You won't lose much fuel.
When I do mine it just drips out so long as you don't leave it all day ,should be fine .
« Last Edit: December 15, 2018, 09:12:54 AM by spit051261 »
Logged
2010  GT650R in the best colour RED

umop-ǝpisdn

  • Global Moderator
  • Forum Addict
  • *****
  • Offline Offline
  • Posts: 7535
Re: Erratic Engine Behaviour when Warm
« Reply #5 on: December 15, 2018, 10:26:56 PM »

The temp of exhaust does indicate that the rear is more efficient.

I have an idea:

Swap the front and rear ignition assembly, coils, leads and spark plugs, then test the exhaust temp again. While you have the ignition assembly apart, take a very close look at the ignition leads and the end caps that clip onto the spark plug. Look for rubbing, born spots and splits in the covers; anything to indicate arcing. Also check the copper clip inside the end cap to make sure it hasn't been bent in some weird way.

Regarding the fuel filter. ..there is no fuel filter. Just a 'sock' that covers the inlet, which is shared between both cylinders.
Logged
I used to be a sensitive, new age guy, but times have changed and now I am more of a caring, understanding, ninties type.

Pages: [1]