Big Turbo B7 P0302 Misfire

i3oricua

Registered User
Ok. Looking for some help here.

I've got a persistent misfire, P0302 that happens under heavy load. If I ease into the throttle the car accelerates fine but if I plant my foot I get a flashing check engine light and misfires and can't get through the rev range. What I've done to try to correct it. Changed the injectors (new RS4 injectors), changed the coil packs (spares I had in the garage), changed the spark plugs (spares I had, NGK-7RE). Looked at wires where I could and see none broken anywhere.

Additional things done since it was last running and pulling hard: went to 4 port injection (water/meth), 175 bar PRV install, Golf R intake cam install, TFSI cam roller conversion. I don't feel like any of those should be causing misfires, checked timing through VCDS and it looked good. Only code I'm getting is P0302.

Let me know your thoughts. I don't know where to go from here.

Edgar
 

Dan_Avant

Registered User
If it only happens under WOT could it be an intake air leak? Could lean out and cause a miss fire?

Have you had a map since installing WMI, PRV etc?
 

i3oricua

Registered User
If it only happens under WOT could it be an intake air leak? Could lean out and cause a miss fire?

Have you had a map since installing WMI, PRV etc?

Hi Dan. The current map does account for all the new mods except for the WMI. But even with it (the WMI) turned off it still does it.

I suppose that it could be running lean but it only does it on cylinder 2.
 

I'm Just Rob.

Moderating or something,
Staff member
Moderator
VCDS Map User
Gold Supporter
Evening Edgar, can you back track a bit through your data logs to see what has changed on a specific date logged to account for the misfire.
Something must have changed , maybe getting back to an earlier data log may help pin point something.
 

Pie-eyedpiper

Registered User
Are you sure your coil packs and plugs are all good? Have you tried swapping them over with ones you know to work ok?
 

i3oricua

Registered User
Evening Edgar, can you back track a bit through your data logs to see what has changed on a specific date logged to account for the misfire.
Something must have changed , maybe getting back to an earlier data log may help pin point something.
Hi Rob. I've had my tuner review the logs and we went through the changes. Waiting to hear more back from him and see.
shot in the dark, plug gap maybe?
Thank you but its done it with 2 different set of plugs, the first being the NGK BR8E or whatever they are and the second being the 7E's. The first plugs were gapped at .032 and the second set .028.
If it's only misfiring on cylinder 2 and you have changed injectors and coils and still remains on cylinder 2 . Could be a wiring issue but I suspect you have probably checked that. I would check the compression across the 4 cylinders and make sure you haven't got an issue with loss of compression on that one cylinder.
Cireyect, done all the above and need to check compression but my battery is dead now out of nowhere so luckily the weather has been good and I get to ride the Ducati as a bi-product. Although I have the battery on a tender right now I think the battery is just bad and will look at a new one. Now I'm googling to see if a bar battery can cause misfires. Mixed reviews on the internet but I may be on to something.
Are you sure your coil packs and plugs are all good? Have you tried swapping them over with ones you know to work ok?
Hello and thank you. I'm fairly certain at this point unless i just have really terrible luck which is not totally out of the question.

Edgar

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Pie-eyedpiper

Registered User
Hello and thank you. I'm fairly certain at this point unless i just have really terrible luck which is not totally out of the question.

Edgar

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Hi Edgar,
It was only a long shot. I would have thought you'd have covered all these things already.
 

Sygh2k

Active Member
Gold Supporter
Hi edgar, just looked at some of your logs out of interest really as im only just getting started with tuning logs but, i dont know if its normal but your timing on cylinder 4 seems to pull 2or3 degrees more than on the other 3 cylinders, dodgy knock sensor or something like that?
 

i3oricua

Registered User
Hi edgar, just looked at some of your logs out of interest really as im only just getting started with tuning logs but, i dont know if its normal but your timing on cylinder 4 seems to pull 2or3 degrees more than on the other 3 cylinders, dodgy knock sensor or something like that?
It's nothing to be concerned about unless it's pulling around 12 or above if I remember right. The timing is generally pretty "clean" and the engine will always hear some sort of knock and the ECU will correct for it by pulling timing but in tuning you should aim to tune without pulling any timing unless you're trying to eek out every but of power from the engine.

This is my basic understanding of it all but understand that I've never done any tuning.

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Sygh2k

Active Member
Gold Supporter
It's nothing to be concerned about unless it's pulling around 12 or above if I remember right. The timing is generally pretty "clean" and the engine will always hear some sort of knock and the ECU will correct for it by pulling timing but in tuning you should aim to tune without pulling any timing unless you're trying to eek out every but of power from the engine.

This is my basic understanding of it all but understand that I've never done any tuning.

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Ah right, it was more that 1,2,3 look similar then 4 is different. In my head it doesnt seem right but its all a bit new on this front to me
 
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