2010 A3 1.6 SE Technik BSE Engine P0304 - Help needed diagnosing this misfire - Tried all the usual suspect parts

THE CAR
2010 A3 1.6 SE Technilk
Petrol
Sportback (5 door)
77k Miles
Cat D due to some minor rear bumper damage in the past.


THE FAULT
First started on the motorway, 1 hour into the drive i got a puff of white smoke out the exhaust then down to 3 cylinders straight away. Left it with a garage who diagnosed it as cracked piston rings on cylinder 4 so got a replacement engine fitted and it ran fine for a few miles then misfired on number 4 again with only p0304 codes on OBDeleven. then i tried new coilpack plugs and leads. again it ran fine for a few miles then misfired again. Then replaced injector and same problem.... lastly we tried a bank 1 o2 sensor and needless to say that didnt work either,

At a bit of a loss here now as ive fired all the parts at it now and still gettin same problem. Is there anyway i can use OBDeleven to monitor blocks/live data to see what is causing this annoying misfire..... Im guessing it killed the original engine too so needs sorted asap before same thing happens again. Im not driving it now till its fixed.. If it gets fixed that is..:aargh4:

1st job, all cylinders compression test.

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Originally Posted by Crasher

1st job, all cylinders compression test.

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Hi crasher, Sorry i never mentioned first time but compression test has been done. 150 - 155psi in all 4..... Also have spark and fuel...... Might be worth noting that when we pulled the plug lead off slightly so spark was jumping from lead to plug then it started to run on all 4 again..... That mechanic told me to put a break in the HT lead and insulate it.... He called it putting a delay in the spark..... I call it a fire hazard and would rather it was fixed properly....

Get a new set of leads.

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Originally Posted by Crasher

Get a new set of leads.

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Did ya read the post?

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Quote:

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Originally Posted by Crasher

Get a new set of leads.

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Its had new leads. Plugs. Injectors. Coilpack. O2 sensor. The lot

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What sort of lead quality?

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Originally Posted by Crasher

What sort of lead quality?

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OEM parts from local reputable autoparts store. Not cheap ebay leads. Also swapped out no 4 lead with known working one from original set and still intermitant missfire.

Is there any live data i can monitor when problem is occuring to try see whats causing it.

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I read post 3 again and understand now, what he did was create a sort of capacitive discharge function, this raises the spark voltage and is a trick we use on carb or K-Jet cars when they are driven in and out of the units for a few weeks and they foul the plugs up, you keep the lead away from the plug by a centimetres or so until the plug electrodes get hot and clean themselves up so this suggests the problem is with the plug or with excessive fuel going into that cylinder so with the plugs being new (what are they EXACTLY?) and the fault being on the same cylinder that suggests an injector fault, were these carried over from the old engine? Is the engine a BSE as if it is, the injectors have been upgraded to a new version, 06A 906 031 CT which is a VDO A2C59506220, these are £167.35 genuine which you should be able to get for a lot less from a motor factor who sells VDO, Euro Car Parts don't list it off the shelf.

Quote:

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Originally Posted by Crasher

I read post 3 again and understand now, what he did was create a sort of capacitive discharge function, this raises the spark voltage and is a trick we use on carb or K-Jet cars when they are driven in and out of the units for a few weeks and they foul the plugs up, you keep the lead away from the plug by a centimetres or so until the plug electrodes get hot and clean themselves up so this suggests the problem is with the plug or with excessive fuel going into that cylinder so with the plugs being new (what are they EXACTLY?) and the fault being on the same cylinder that suggests an injector fault, were these carried over from the old engine? Is the engine a BSE as if it is, the injectors have been upgraded to a new version, 06A 906 031 CT which is a VDO A2C59506220, these are £167.35 genuine which you should be able to get for a lot less from a motor factor who sells VDO, Euro Car Parts don't list it off the shelf.

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Thanks Crasher....Plugs are NGK R..... Also got one spare denso plug and same problem... Also injectors were carried over first of all then when problem reoccured i used the injectors that come with replacement engine. Then same thing..... Then i swapped only cylinder 4 injector 1 more time and used one from cylinder 2 on original injectors which i seen as known working. So with 3 injectors tried id say they aren't the problem but im no mechanic..lol
Do the injectors need coding to ECU or something?