Audi A4 - Audi A4 1.8T BFB single cylinder misfire

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Fri 17 Jan 2025 22:26
Audi A4 - Audi A4 1.8T BFB single cylinder misfire - jimmy4mech

i have an audi a4 2004 1.8t that i recently bought, the car has a misfire on cylinder 2 so i replaced the coilpack and the problem went away but only when the car is static, asin not moving and engine running it has no misfire but when you put the car under load after 2000rpm cylinder 2 has a dead misfire, no stuttering or hesitation just goes completly dead, i have ruled out that its not the piston rings as it dosnt smoke i would need to do a compresion test to confirm but im pretty confident it isnt that i know its not a stuck valve as its not constant its only under hard acceleration, i have replaced the coil packs and spark plugs also i checked the coil wires that sit above the exhaust as they are known for splitting due to the heat of the exhaust, cylinder 2 had 2 wires that had the outer case breaking away but not damaged the wire to what i could see so i eletrical taped them to see if the problem persists, which it did. is it the wires that are causing me the misfire, is there damage that i cant see thats caused by the heat and the wires actually need repairing

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Fri 17 Jan 2025 23:30
Audi A4 - Audi A4 1.8T BFB single cylinder misfire - elekie&a/c doctor
I would definitely do a compression test first , and move from here . Could be other issues, but this is a good starting point.
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Fri 17 Jan 2025 23:30
Audi A4 - Audi A4 1.8T BFB single cylinder misfire - edlithgow

I;d guess the wires wont interchange, so you cant do swaptronics to see if the fault moves with the wire?

(and other components, but you seem to have already replaced them with new)

In that case I suppose my next try would be toreplace the damaged wire with a new one.

Edited by edlithgow on 17/01/2025 at 23:34

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Fri 17 Jan 2025 23:31
Audi A4 - Audi A4 1.8T BFB single cylinder misfire - edlithgow

DP

Edited by edlithgow on 17/01/2025 at 23:32

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Sat 18 Jan 2025 21:36
Audi A4 - Audi A4 1.8T BFB single cylinder misfire - jimmy4mech

update, i did some investigating today and the earth wires for the coils that bolts the the rocker cover had started to degrade and break away so i cut them back and added new terminals to the end and rebolted them to the cover, now when checking live data the car no longer counts misfires while its stood running although still misfires on high revs but also checking dtc's showed a code for low fuel level confirmed by the fuel light being on, i did notice this when i bought the car (i know) just never really dawned on me that this could cause such a problem to 1 specific cylinder thinking it would throw misfire codes to all cylinders, could this be my cylinder 2 misfire accompanied by the dead coilpacks i replaced at the start i have yet to do a compression test ill get back with the results from that next week, i did check for vacume leaks even though its one specific cylinder better to be safe than sorry right? and also checked for more split wires but no others apart from the earths to the coils

Edited by jimmy4mech on 18/01/2025 at 21:38

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