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Misfires at (low) boost

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Hi there again!

The last brain pain creator i have been working on gave me the need to consult you all once more.

The car i have been working on is giving me (random) misfires from 3000 rpm/0.10 kpa. At least it sound like, feels like and acts like misfires. Something with a chicken. So we started with swapping spark and coils. Still the same. The engine has vvt's, so disconnected those. Still the same.

IAT is not weird high. Nor the engine its self. Im thinking something mechanical but its hard to eliminate components. We did a compression test and all where exactly the same pressure(150). When listening to the engine i do think that there is a lot of noise coming from the valve train. I will include a sound clip with this post.

Engine is a VQ35(yes again :) running on RON98

You guy's have some suggestions? Thanks in advance!

Kind regards,

Vincent

Attached Files
  • youri-31-05-missfire-3000-rpm-0.2-bar-002.wav
  • Attachments may only be downloaded by paid Gold members. Read more about becoming a Gold member here.

I can't really tell much from that sound file unfortunately. I'd be starting with the basics such as making sure you don't have a boost limit active. You could log any cut % to make sure that isn't the case. You may find that you need to close up the spark plug gap slightly but you 'should' be absolutely fine at 0.1 bar positive pressure.

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