[goldchain100]

Hi all memebers. i hope someone can help with my problem i have a 03 vectra 2.0 turbo and it keeps throwing a code for random multiple misfire went i leave the the idleing. car drives great other wise. its just on idle it misfires. i have checked and changed lots of part to try and fix it but to date have not. code is p0300. the car is a bit hard on petrol as it does only 50 mile on £20 went engine mangment light is off an went its on about 65 mile. I've changed coilpacks. temp senor, sparkplugs fuel filter, mass airflow, both o2 senors, checked all vac pipes for leaks, egr vaule cleaned and checked it for leaking, intercooler hoses.
the one thing that pluzzes me is went i switch on rear heater, air con and front window heater switches the car runs fine on idle. hope someone can help.


thanks geoff

[goldchain100]

Hi i have worked on car for 12 years. I brought the car to my local vauxhall garage which said it was coilpacks so i brought new ones but it wasn,t the coil packs. the starts ,drives fine its just misfires when idleing and is a bit hard on petrol. was told could be ecu fault

[goldchain100]

Hi i,ve already done a compression test and it was fine. i have checked most things i could think off just though someone might off came across this problem b4 on this forum. The car will idle fine when i switch on the aircon, front window demisser an rear window demisser at the same time and idle fine nice and even but misfire when i switch all off again.

[zerosu]

Hi, sorry for my bad English,are you try to replace the main shaft magnetic encoder.

[goldchain100]

I have changed both camshalf and crankshalf senors but still not fixed. thanks for the replys

[mpautoservis]

If I understand everything ...
I think you should clean up injectors ... In Serbia, there are many vehicles with error P0300 ...
I use WYNN`S liquid with which clean injectors and clean the dirt from the valve ...

   

[free]

Hi i no it is not a vectra but had a vauxhal astra G I think it was 2013 in work shop with miss fire that we could not find. It ended up to be a bad earth to the ECU body. Fitted a New made up wire from battery to one of the four bults on ECU body. and all ok now may help you !!!

[andrewbishop]

Start with basics is the air fuel mixture right(high hydrocarbons at exhaust)
if high poss air leak before or around upstream o2 sensor
what color are the plugs
does it misfire before it goes into closed loop
what equipment do you have available ie diagnostic to look at o2 values when in closed loop

It sounds to me like its getting to much fuel thats why when you add load it runs ok as the extra fuel helps with the load

[Yoshimura]

Start with basics is the air fuel mixture right(high hydrocarbons at exhaust)
if high poss air leak before or around upstream o2 sensor
what color are the plugs
does it misfire before it goes into closed loop
what equipment do you have available ie diagnostic to look at o2 values when in closed loop

It sounds to me like its getting to much fuel thats why when you add load it runs ok as the extra fuel helps with the load

Check your timing and alternator chargeing rate


BR