Still misfiring at idle.

Feb 9, 2019
11
1
Hello there I have recently purchased a lovely 2008 Cupra with the BWJ engine code!

I noticed at idle when the car is warm it will randomly pop out the exhaust whilst misfiring and you can feel these jerks in the car!

I have been to the garage and vcds said cylinder 2 misfiring and bank1 too lean which is the first exhaust sensor, this was broken by the mechanic when I got a custom downpipe installed as it was so stuck.

Have a new one on order.

Changed plugs and coils. Still doing it.

New thermostat as it needed one and new camshaft sensor.

Compression test was also done, this resulted in the same compression on all 4 cylinders.

(Suspected leaking injector)

Got the injectors cleaned and tested they was fine still almost flowing like new and all seals replaced, also had a carbon clean!

STILL DOING IT!

Oh and i removed the metal inserts from inside the head as one of them had snapped in half from excessive carbon build up!
Must of been very lucky tbh!
Left the manifold flap in so I don’t get a code pop up! So no worries there.

I have heard the horror stories of people’s engines failing due to a dodgy injector with the same symptoms as what I have now!

Also I would like to add if I rev the engine with the clutch in whilst driving (rolling) the revs don’t seem to drop instantly,

this also happens when changing gear sometimes so it bites on the clutch in the next gear harder than it should as the revs are not falling as fast as they should whilst shifting. (Feels that way to me) (Very annoying)

Am hoping there is an air leak but I can’t see anything visually.

Thinking pvc valve or dump valve now I don’t know

Tried to give as much information as possible as I know this has been discussed a few times before and can become old very fast.

About to give up on the car but I don’t want to as it’s just had a new gearbox just before I bought it and drives lovely tbh it’s just the idle issue.

If anyone knows something that could help then I will hear from you :)

Thanks allot........ Dan
 

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fozzybear

middle aged speed freak
Feb 4, 2006
317
19
halifax,west yorks
Hello there I have recently purchased a lovely 2008 Cupra with the BWJ engine code!

I noticed at idle when the car is warm it will randomly pop out the exhaust whilst misfiring and you can feel these jerks in the car!

I have been to the garage and vcds said cylinder 2 misfiring and bank1 too lean which is the first exhaust sensor, this was broken by the mechanic when I got a custom downpipe installed as it was so stuck.

Have a new one on order.

Changed plugs and coils. Still doing it.

New thermostat as it needed one and new camshaft sensor.

Compression test was also done, this resulted in the same compression on all 4 cylinders.

(Suspected leaking injector)

Got the injectors cleaned and tested they was fine still almost flowing like new and all seals replaced, also had a carbon clean!

STILL DOING IT!

Oh and i removed the metal inserts from inside the head as one of them had snapped in half from excessive carbon build up!
Must of been very lucky tbh!
Left the manifold flap in so I don’t get a code pop up! So no worries there.

I have heard the horror stories of people’s engines failing due to a dodgy injector with the same symptoms as what I have now!

Also I would like to add if I rev the engine with the clutch in whilst driving (rolling) the revs don’t seem to drop instantly,

this also happens when changing gear sometimes so it bites on the clutch in the next gear harder than it should as the revs are not falling as fast as they should whilst shifting. (Feels that way to me) (Very annoying)

Am hoping there is an air leak but I can’t see anything visually.

Thinking pvc valve or dump valve now I don’t know

Tried to give as much information as possible as I know this has been discussed a few times before and can become old very fast.

About to give up on the car but I don’t want to as it’s just had a new gearbox just before I bought it and drives lovely tbh it’s just the idle issue.

If anyone knows something that could help then I will hear from you :)

Thanks allot........ Dan
One thing haven,t seen changed is coilpac these can go any time ...was a recall on coilpacs on all vag group and yours comes in at around time...check and see as will still replace if one of faulty batch free..did you change the vvt valve
 
Feb 9, 2019
11
1
Hi there thanks for reply, all the coil packs were replaced including spark plugs and was still doing it so put old ones back in!

Do you have a part number for the valve as I haven’t changed that,

I was thinking maybe the clutch is grabbing ever so slightly but who knows


Sent from my iPhone using Tapatalk
 

Fooxy

Active Member
Nov 27, 2015
19
5
Sorry for resurrecting an old thread, but out of interest did you manage to sort your issue?

If so what was the cause?
 
Feb 9, 2019
11
1
Sorry for resurrecting an old thread, but out of interest did you manage to sort your issue?

If so what was the cause?

Started doing it again and now I have this code can anyone help the hpfp is new and the lpfp is new from VDO 4.4 BAR thanks in advance
 

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Legojon

I only wanted a remap
Staff member
Moderator
Jul 7, 2015
5,284
2,713
Oxygen sensor (again) or vacuum leak. If you've had the injectors cleaned and assuming the fuel filters ok. It must be too much air getting in. You could probe the oxygen sensor, make sure it's within tolerance.
 
Feb 9, 2019
11
1
Oxygen sensor (again) or vacuum leak. If you've had the injectors cleaned and assuming the fuel filters ok. It must be too much air getting in. You could probe the oxygen sensor, make sure it's within tolerance.

Thanks I just done the test and got 0 back from the oxygen sensor side trying all pins and the other side of the clip was between 0.24 and 0.35
 

Legojon

I only wanted a remap
Staff member
Moderator
Jul 7, 2015
5,284
2,713
Thanks I just done the test and got 0 back from the oxygen sensor side trying all pins and the other side of the clip was between 0.24 and 0.35

That looks about right to me (in tolerance and on the lean side). Vacuum leaks can be hard to find. Maybe check over the pcv system next?
 
Feb 9, 2019
11
1
That looks about right to me (in tolerance and on the lean side). Vacuum leaks can be hard to find. Maybe check over the pcv system next?

Just to clear up i only unclipped the sensor harness I did not remove (unscrew the sensor) then turned ignition on with engine off then I done the test, how does that test the sensor when it wasn’t even connected and it gave a reading of 0. sorry if i sound stupid im new to this multimeter testing.

I will check the pvc pipes, I have a pvc blocker so I only have one pipe coming off of there but I’ll look around the brake booster hose ends etc etc.

I will use some spray and hopefully find something leaking. Thanks
 
Feb 9, 2019
11
1
That looks about right to me (in tolerance and on the lean side). Vacuum leaks can be hard to find. Maybe check over the pcv system next?

Ok my mistake,

I just tested the Continuity on the oxygen sensor wire, it was around 14.05. If that is good then I need to find a garage with a smoke tester as I haven’t found any leaks yet!

Fuel filter was changed for OEM version last year so I’d say it’s still good.
 

Legojon

I only wanted a remap
Staff member
Moderator
Jul 7, 2015
5,284
2,713
Just to clear up i only unclipped the sensor harness I did not remove (unscrew the sensor) then turned ignition on with engine off then I done the test, how does that test the sensor when it wasn’t even connected and it gave a reading of 0. sorry if i sound stupid im new to this multimeter testing.

Ah right... generally I would have it all connected, put two needles / long pins into the back of the connector where the wires go and touched the multimeter on the pins.
 
Feb 9, 2019
11
1
Late Update, I took the car to a well known tuning company and it was a half working MAF sensor.

The last owner had put it on upside down and installed a mk6 intake on the wrong car (my car) :(

Water also got into the maf from the scuttle panel (heavy rain) so it was flooded for some time, but now I have a new oem maf and also changed valve cover gasket as that was leaking a tiny bit from water sitting on top for so long, so now all is good. Scuttle is sealed too.

So thanks to the garages for saying it was fuelling and not checking the maf on vagcom. Could of saved me allot of time and money.

Now it drives really strong even one of them srt 4x4 cars couldn’t shake me at stage 1 But then a m5 did
 
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