GS300 cold misfire

[taylo02]

Hi guys,

I have a '55' GS300 and I have noticed that within the last month or so, there is a definite misfire when the engine is cold. I have changed the spark plugs and I followed a youtube video to check for a faulty ignition coil (if the rev drops when it is slightly removed it is ok, but if there is no change in idle, it's faulty) but this has not resolved the issue. I have checked all of the connectors and I have also cleaned the MAF but this has made no difference. Any thoughts? Furthermore, I also note that the car does not like going from 25mph-30mph as there is a bit of hesitation / judder. I am not aware of the gearbox oil being changed, however I am not sure if this would help the problem. I would be grateful for any help as this is my first post on the forum.

Thanks in advance, Craig :)

[ColinBarber]

Hi Craig

The misfire and hesitation at 25 mph, did these occur at the same time? If so I wouldn't spend time thinking about the transmission.

Is the idle rpm low? Do you have any warning lights?

There are a few potential causes such as fuel injectors dirty (have you tried an injector cleaner?), oxygen sensors, VVTi oil control valve, carbon build up on the intake / valves due to vehicle having direct injection.

How many miles has the vehicle done?

[taylo02]

Hi Colin,

thanks for the reply. As far as I am aware, yes, these started around the same time. The idle is 600rpm when in drive and I haven't noticed any fluctuation in rpm when in park or neutral.  I had a VSC light on the dashboard, however I cleaned the MAF and changed the fuel cap and the VSC turned off. I have the tech software and I think that this showed the bank 2 sensor 2 as being problematic, but this error was cleared around 2 months ago. I have tried bg44k around one month ago and it didn't really change how the car performed, but I read it helped with carbon deposit build up. The car is on around 150k miles with full service history. I think the dirty fuel injector could be the problem?

 

 

[ColinBarber]

1 hour ago, taylo02 said:

I have tried bg44k around one month ago and it didn't really change how the car performed, but I read it helped with carbon deposit build up. The car is on around 150k miles with full service history. I think the dirty fuel injector could be the problem?

The additive should help with dirty injectors, but I'm not sure how effective they really are and if one treatment is enough. Unfortunately it won't do anything for carbon deposits with your type of engine because it only has direct injection so the fuel never touches the intake manifold and valves.