Mini Cooper r50 2002
Hi
currently got a misfire in cylinder 1 on idle and under load. I have changed spark plugs, coil packs and injectors and still misfiring. Engine light comes on only sometimes but the misfire is constant. Wondering if it’s the exhaust valves but not sure as I’ve done the paper/ tissue test on the exhaust exit (not sucking the paper/tissue back in). Anyone have any suggestions?

 

Welcome to the forum

 

Welcome And a couple of questions, how did you determine it was #1 cyl & what was the colour of the spark plug electrode from #1 compared to the other 3, did you do a compression test,? As you have already replaced most of the elec components & injectors it does sound compression related
Russ from downunder

 

I plugged a code reader in and it came up with cylinder 1 misfire and engine running too lean.
all spark plugs were not wet, they were dry however,
whilst screwing in cylinder 1 spark plug it didn’t seem to get tight enough to stop screwing, it just kept turning which I found weird.

 

if your saying that #1 spark plug would not tighten then it would not be sealing in the head and could be sucking in air on the intake stroke, causing your lean/misfire problem, the cause would probably be a stripped thread in the head, which is a major problem, remove the plug and get a flashlight to inspect the thread in the head, if it's just turning on not tightening you should be able to see the damaged threads
good luck
Russ

 

Hope it is the spark plug threads that are stripped and not the head. You DEFINITELY have stripped threads on at least one of the surfaces. Sorry.

 

Heli coil if its stripped out.

https://www.ecstuning.com/Mini-2003-...Thread_Repair/

 

okay thank you, I’ll have a look!