Intermittent misfire

Cody Forbes cody at
Sun Oct 15 21:33:29 PDT 2017

Could be a leaky injector(s) putting a bunch of fuel in the engine overnight. Could be the opposite of they: fuel pressure leaking down overnight and not priming quite enough before starting. Could be oil leaking out of the cam phasers over night maybe.

I'd try some injector cleaner stuff. It's not a miracle product, but it can't hurt.

-Cody Forbes (mobile)

> On Oct 15, 2017, at 8:05 PM, Tihol Tiholov <t.tiholov at> wrote:
> Hi, all.
> The patient is 2002 A4q 3.0, auto.
> Occasionally, when I start it first thing in the morning it'll misfire with
> CEL coming on or even blinking. Usually, when damp and cool, close to
> freezing. After 15-20 seconds with a bit of throttle input (to which the
> engine doesn't always react), it clears up and it's fine for the rest of
> the day. After shutting down and restarting, it's all good.
> Idle is often a bit rough, but again intermittently. Not sure, if there is
> a connection.
> Pulled trouble codes and they were all intermittent:
> - Random cyl. misfiring,
> - Every cyl. misfiring individually, except #6, 5 codes total for this,
> - Catalytic converters heating circuits.
> Seems like something resets itself at 2nd restart.
> This morning it was misfiring at first start with CEL blinking, then after
> shutting it off and restarting, no CEL, all was well for several restarts
> and 30-40 kms short trips.
> Any info, BTDT's, etc. welcome
> -- 
> Tihol
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