Engine Misfire P0300

[Sam_100]

I have pressed down on the valve. No change. I even tried to make a seal around the base. It sound like it's coming internally. But I am not sure if its normal or not. I can't access another VF with an LFX to confirm one way or the other. So relying on someone on this forum to confirm for me with their car. This also applies to the Evaporative solenoid surge valve and the noise it makes (7 sec into the video in the first post) when you activate it.

 

[Geoff6666]

My L77 manual has developed a cough (not Covid) when I hit the accelerator. It makes the gear changes more difficult to do smoothly when driving quietly. Also a kick-back through the gearbox if driving at low to medium rpm if I give the throttle a stab.
From my old-school days this would normally be caused by a manifold air leak. Should that throw a DTC on a VF?
I run it on E85. 100,000Km.. I have changed the plugs and the old ones looked in excellent condition.
Apart from the cough it runs perfectly.
Any suggestions on what I can check for? Also as I run on E85 should I be using any additives or injector cleaner?
Or any other snake oil?
Thanks in advance for any advice or opinions.

 

[krusing]

Worked out the air sucking noise. It's coming from the PCV that connects to the manifold. It only does it when you give the accelerator a squirt from idle. You can hear it in this video at the 4 sec mark -

I have not noticed/heard this sound before. Is this normal for a VF LFX (and am chasing shadows) or do I have a leak somewhere?

My OCD is starting to kick in with this problem

See if you can get the intake smoke tested, that will show up any vac/intake leaks.

 

[krusing]

My L77 manual has developed a cough (not Covid) when I hit the accelerator. It makes the gear changes more difficult to do smoothly when driving quietly. Also a kick-back through the gearbox if driving at low to medium rpm if I give the throttle a stab.
From my old-school days this would normally be caused by a manifold air leak. Should that throw a DTC on a VF?
I run it on E85. 100,000Km.. I have changed the plugs and the old ones looked in excellent condition.
Apart from the cough it runs perfectly.
Any suggestions on what I can check for? Also as I run on E85 should I be using any additives or injector cleaner?
Or any other snake oil?
Thanks in advance for any advice or opinions.

Run some live tests and should indicate any errors,
Scan it for any Historical DTC's.

 

[Sam_100]

Been a while but thought I better provide an update in this issue.

1. I checked the plugs myself and the correct ones have been installed.
2. I replaced the purge valve solenoid myself and noticed it was making the same noise. Haven't had a chance to connect my mechanic's scanner (he's back from his holiday) to see if it is still reporting 'malfunction'.
3. As far as the misfire is concerned it only did it once more about a week after the first time. Since then I have driven it regularly to work and back and even too a return trip to Melbourne. No misfires or engines lights have come up. I think the problem may have been bad fuel.

As for the vacuum noise when applying throttle in park, my mechanic said that's normal.

Hopefully the misfire doesn't come back!