[Gabor]

Hi all,

I've got a misfire which I can't seem to solve.

The misfire occurs once the car is warm and idles for more than a minute or so. After the odd shakes and vibrations, it starts to shake quite a bit and flashes the CEL (DME fuel mode also switches from 2 to 3). It can also occur while driving slow (low revs, low load) but not when driven enthusiastically.

Codes (always come together):
29CF - Combustion misfires, cylinder 3
29D9 - Misfire at low tank fill level (tank is not actually low)

Plugs and coils were changed around 15,000 miles ago + walnust blast to clear carbon deposits.

What I tried:

- New spark plugs (I did notice some oil on cylinder 3 spark plug - possibly valve cover gasket leak)
- Swapped coils 2 and 3
- Upped IDLE rpm to 950
- Changed MHD map back to stock (was stage 2)

Regardless of the changes and brand new plugs, I keep getting cylinder 3 misfire almost straight away.

It's driving me crazy so I thought I make a post here in case anyone can guide me in the right direction. Thanks in advance!

[Rule1977]

Originally Posted by Gabor

Hi all,

I've got a misfire which I can't seem to solve.

The misfire occurs once the car is warm and idles for more than a minute or so. After the odd shakes and vibrations, it starts to shake quite a bit and flashes the CEL (DME fuel mode also switches from 2 to 3). It can also occur while driving slow (low revs, low load) but not when driven enthusiastically.

Codes (always come together):
29CF - Combustion misfires, cylinder 3
29D9 - Misfire at low tank fill level (tank is not actually low)

Plugs and coils were changed around 15,000 miles ago + walnust blast to clear carbon deposits.

What I tried:

- New spark plugs (I did notice some oil on cylinder 3 spark plug - possibly valve cover gasket leak)
- Swapped coils 2 and 3
- Upped IDLE rpm to 950
- Changed MHD map back to stock (was stage 2)

Regardless of the changes and brand new plugs, I keep getting cylinder 3 misfire almost straight away.

It's driving me crazy so I thought I make a post here in case anyone can guide me in the right direction. Thanks in advance!

Check your battery's health. A low battery can cause misfires. Also could be injectors.