R56 Cylinder 4 misfire at idle only

Reply Subscribe

Thread Tools

Search this Thread

Jan 30, 2020 | 06:43 AM

1silvermini

Thread Starter

Neutral

Joined: Jan 2020

Posts: 3

Likes: 0

From: South Florida

Cylinder 4 misfire at idle only

I have a 2010 Cooper S with a cylinder 4 slight misfire on idle only. Misfire clears up with the slightest increase in RPM . I have swapped injectors, and coil packs...no change.

Jan 30, 2020 | 09:06 AM

MiniToBe

6th Gear

iTrader: (2)

Joined: Jan 2015

Posts: 4,339

Likes: 437

From: Philadelphia PA

did you do a compression test? how many miles? timing chain ever replaced? carbon cleanup on the intake valves? did you also swap spark plugs, are they gapped properly?

Jan 30, 2020 | 10:17 AM

1silvermini

Thread Starter

Neutral

Joined: Jan 2020

Posts: 3

Likes: 0

From: South Florida

I did a compression test and they were all between 10% of each other ,the timing chain and guides,tensioner was recently replaced.i swapped the plugs and had the same results.checked the timing 3 times

Jan 30, 2020 | 10:31 AM

MiniToBe

6th Gear

iTrader: (2)

Joined: Jan 2015

Posts: 4,339

Likes: 437

From: Philadelphia PA

any carbon build up on the intake valves? did you check for codes, even if there is no check engine light?

Jan 30, 2020 | 10:37 AM

Minidogger

4th Gear

Joined: Mar 2018

Posts: 418

Likes: 79

From: Iowa

You can try cleaning the MAF too.

Jan 30, 2020 | 11:00 AM

1silvermini

Thread Starter

Neutral

Joined: Jan 2020

Posts: 3

Likes: 0

From: South Florida

It’s throwing a P0304 code for misfire as well as the check engine light. I soaked the valves in sea foam overnight but did not get them walnut blasted