Cylinder 2 misfire any one have an idea of what to check next?

[Ben Cordy]

Hi all some of you may have seen my post a few days ago about this. I'm occasionally getting a eml with a fault code for a cylinder 2 misfire. It only happens when idling, there are no issues whatsoever when above 10,000 revs but whilst idling below this the car vibrates quite a bit and feels almost like it's struggling to run. Very occasionally (maybe every 3 days or more) it'll be running rough whilst idling then the eml will come on and the revs will become quite iratic. Turing the ignition off an on usually sorts this and the light goes out.

So far:

I've swapped the ignition coil for cylinder 2 but the fault code stayed with cylinder 2.

I removed and checked the spark pugs which were fine, looked pretty much new.

I checked the wiring loom and found the wires going to the cylinder 2 injector had been stripped, so i sealed these with some self amalgamating tape.

I'm lost for what to do next?

Any ideas?

[mattievrs]

Replace the loom next.

[Ben Cordy]

Replace the loom next.

Any idea what sort of price that might be? I would go down the scrappy route but none of the Leeds ones have the 1.2!

Would I need to replace the whole engine bay loom or could I just swap out the injector wiring?

[DanGum]

when i had my mis firing, it was a faulty wiring loom in the head for cylinder 1. it cost me £120 to fix. But that was at a vag specialist so a local indy would be cheaper!

[Ben Cordy]

I'm beginning to think that must be the issue, a number of people have suggested that now and there is clearly damage to the wiring for the cylinder 2 injector. Although I want to be sure, is there any way to test the function of the injector itself to make sure that's not at fault?

[DanGum]

ive got no idea dude sorry :(

[VWD]

Simple suggestion - plug leads ,have you tried a new one on No 2 ?

[Ben Cordy]

At the risk of sounding stupid which plug leads are you referring to? If you mean coil pack I tried swapping them but it didn't help.

[Tech1e]

Personally I'd swap the injector around next and see if the missfire moves, change a lot of injectors, most actually over fuel.

[Tech1e]

Simple suggestion - plug leads ,have you tried a new one on No 2 ?

1.2 won't have plug leads, it's a coil per cylinder.

[Tech1e]

when i had my mis firing, it was a faulty wiring loom in the head for cylinder 1. it cost me £120 to fix. But that was at a vag specialist so a local indy would be cheaper!

Diesel is a completely different set up.

[Ben Cordy]

As I thought! Are the injectors separate? For some reason I thought they were part of a single rail? Any tips for swapping them? Not really done anything with fuel delivery yet (about the only thing I haven't fiddled with)

[Tech1e]

The injectors are separate from the rail. De pressurise the fuel system by removing fuel pump fuse or disconnecting the fuel pump under the rear seat and turning over. Remove the two screws holding the rail down and lift up. Pop the clip off holding the injector into the rail and remove. When you refit make sure all the seals are there and in place properly.

[Ben Cordy]

That's brill will give that a go over the weekend. Seems like the obvious issue to me but we'll wait and see!

[Ben Cordy]

Quick random question but when idling where should my rev sit? Mine always sits on the marker below 10,000 revs (so 8000 rev i think). Is this normal? I only as as I've seen a few videos of cold starts in the same model on youtube and they all idle at 11,000 or there abouts. If mine isn't right how do I go about changing that?

Edited 16 March, 2012 by Ben Cordy

[fordfan]

Normally around 850rpm, your figures are out by a factor of 10. Idle speed is controlled by the ECU and is not adjustable, you could give it a chance of being correct by ensuring that the throttle body is clean, the engine coolant temperature sensor works as it should and that there are no air or fuel leaks.

[TimVRS12]

You could eliminate the injector by unplugging it whilst on idle.

If there is a significant dip in performance you can rule it out. If not a lot happens then it would suggest it's knackered.

Same can be done with the lead.

[Tech1e]

I wouldnt trust the above.

We test them by measuring delivered fuel quantity and it's suprising the difference. We have a TPi on this issue, the fault manifests itself as a missfire but it's not as simple as it not working. Normally they actually over fuel causing the imbalance rather than an actual missfire.

[Ben Cordy]

Thanks for you responses guys. I'm running a tank of premium fuel with injector cleaner in to see if that improves things, so far it's still idling roughly but it hasn't given me an engine management light yet which is an improvement. Removing the injectors wiring whilst idling won't do any damage then?

[Ben Cordy]

Thanks Tech1e, think I'm fast realising I might need to drop it into a garage to get them to test the injection system out.

[Ben Cordy]

Well after popping in some premium fuel and a bottle of redex I've gone without a single issue. Will have to see once I've drained the tank and cleaner.

[joe-on-the-rock]

I just bought a Skoda fabia HTP 1.2 2003 54000 miles two weeks ago, and I am having exactly the same problem. When idling the engines shakes like crazy bouncing up and down with low revs. Brought it to a friend who has a computer to plug it in and got it diagnosed a cylinder 2 misfire. Now from different garages I got different solutions, the most extreme is to open the cylinder and replace the valves, plus head gasket and chain set. Other said it was a sticky valve and can be sorted running some liquid called Forty (not to sure about. The warranty company wont pay for the repair and the dealer doesnt want to know about it so I am pretty much screwed. Just wanted to know what I can do to get it sorted the best possible way.

Thanks a lot

Jose

[Ben Cordy]

I guess a lot depends on that particular engine. The misfire code i'm rapidly finding is quite vague. For me I worked out that it seemed to be something to do with the fuel injection so I ran a product called Redex in a tank of premium fuel and so far it seems to have stopped the misfire issue. It still judders a bit on idle however on mine the rev counter doen't move at all, so I'm inclined to think it's possibly something different. My suggestion would be try a tank of decent fuel and some injector cleaner, you never know it may solve it. If not it's only a few quid and probably good for the car anyway even if that isn't the main issue!

Check out

http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_205461_categoryId_255221_langId_-1?cm_sp=Intelligent_Offer-_-Product_Details_Zone_1-_-Blank&iozone=PDPz1#tab3

Seems fairly good stuff.

[joe-on-the-rock]

Thanks a lot, I am gonna keep investigating to see what else can be, apparently at the Skoda dealer they charge 90 quid just for an hour check.....On the other hand I dont want to have the whole cylinder taken apart for no reason until Im pretty sure there is no other way so I might try that product first and see, but keep the post running in case someboday has the same problem and they know how to solve it.

[Avalon]

The only real difference with premium fuels is the detergent package (exception is V Power), everything else is from the same refinery tank just with a different card to mix the additive packages as it's dispensed into whoever's tanker. A tank of 'premium' fuel costs £2-3 more than normal 95RON so is probably worth a go, Asda regularly sell Redex for £1 but remember it's the Petrol injector cleaner you want, they also do a diesel version and a fuel system version along with the expensive version they sell in Halfrauds, Forte is good stuff but it's on par with the expensive Redex treatment in terms of price.

As Tech1e points out though the logical way to prove it's an injector issue vs a loom issue is to swap the injectors round thus proving an injector fault if the misfire travels to a new cylinder or have it properly diagnosed by flow rate testing each injector, by the time you've paid for the diagnosis you may as well have sent them away to have ultrasonic cleaning/testing as it's quite inexpensive but the down side is you'll be without the car for a few days.

Try (more) expensive fuel and/or injector cleaner first, then you can always swap them round if that doesn't help within a few hundred miles.