Fabia 1.2 Misfire at idle

**paulstewart** · 31-05-2012,10:00 PM

Cheers zenman,

I had narrowed it down to the second cylinder miss firing because of a sticky valve but have been trying to avoid taking the head off.

I have flushed the whole engine (engine and new oil) and have been running forte engine flush thought it on BP premium petrol. The forte stuff used to fix the sticky valves on the Zetec engine.

The problem seems to be getting worse now with the forte but I only hope this is the stuff working, removing the carbon stuck on the valves.

I still have another tank to run through the engine and then if no better then the head has to come off.

I am lucky enough to know a mechanic who said he would replace the valves for £360. That is take the head off, 4 new valves, skim head, all back together.

It was his mate a got the car off so feels a bit responsible I think.

Will let you know how it gets fixed!

Thanks guys for your helps.

**Crasher** · 01-06-2012,12:20 PM

3 new valves, not 4. It will be a burnt valve with a worn guide so you will have to replace the exhaust guides as well, if you don't the new valve will fail again in around 20K miles.

**paulstewart** · 01-06-2012,12:59 PM

I was going to replace all the values on cylinder 2. So 4 values per cylinder (12 valve). As cylinder 2 is the only problem (thinking about it, may only do the 2 exhaust valves now).

I have heard that it is heat not getting away from cylinder 2 that causes this carbon build up, so cylinder 1 and 3 are usually fine.

I hadn't thought about replacing the valve guides, I am only doing this to sell the car as it is sitting doing nothing.

Thanks.

**Crasher** · 01-06-2012,06:32 PM

Originally Posted by paulstewart

I have heard that it is heat not getting away from cylinder 2 that causes this carbon build up, so cylinder 1 and 3 are usually fine

Of the last four we have done that I can remember, one had a number 1 failure, one failed on number 2 and one failed on number 3 so that shoots that theory down in flames! If anything, number 3 will run hotter on the 12 valve due to the EGR valve port being there.

1 on 1

1 on 2

2 on 3

**A4 Lad** · 01-06-2012,07:24 PM

Originally Posted by Crasher

Of the last four we have done that I can remember, one had a number 1 failure, one failed on number 2 and one failed on number 3 so that shoots that theory down in flames! If anything, number 3 will run hotter on the 12 valve due to the EGR valve port being there.

Thats only 3 lol