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Hi Everyone! I've got a problem with my Audi rs4 2007 and i'm not able to find the solution. The car make random missfire. I start the car and it run with a light missfire. You can ear it at idle but no dtc. When I accelerate it's even worst and the check engine appear and flash.
I notice when i clear the dtc ( with vcds), the car seem to run smoother for a few minute on idle. Check the link on youtube. I recorded the two oxygen sensor reading and at the start they measure the same value but after 30 second it’s completely different.
Also, you can see my scan from VCDS. The car give me missfire on cylinder 5-6-7-8 when I drove for a few miles but when I drove for a bigger distance all the cylinder have missfire. Check the scan in the link.
I try to swap coil but nothing change. Maybe I need 8 new coils but I’m not sure ? Is a one bad coil can create random missfire
Also, I notice something really strange when I remove the spark plug. On one side, (cyl 1 to 4) the spark plug are carbonized ( really rich) . And the other side (cyl 5 to 8 ) the spark plug are the perfect coffee color. What can cause that ?

What i do during the pass 2 week to solve the problem but no good result

1- Complete carbon clean up
2- Change all the spark plug
3- Change all the injector for new hitachi

4- Compression Test – good
Cyl1: 137 psi Cyl2 : 142 psi Cyl3 : 132 psi Cyl4: 145 psi
Cyl5 : 143 psi Cyl6; 142 psi Cyl7 : 144 psi Cyl8 : 155 psi

5- Change the two Bank 1 o2 sensor

What you think i can do next ??
1- Change the coilpack for 8 new? I don’t think it will solve it
2- Change the Mass air flow ( check the video in the link to see the value on idle)
3- Change the ECU ? By the way witch ECU control the engine( 2 ecu on the RS4). I’ve got a DTC for a faulty memory for ECU2 check the VCDS Scan.

I want to know your opinion about my problem!
Thanks and sorry for my bad english
Félix

Has it ever had new coil packs?

I'd say coilpacks, mine had similar faults. Changed all 8 and problem went away

The previous owner say it change all the 8 coil but i'm really not sure if it's true.

Rw@@dy your RS4 was missfire on every cylinder ??Because i buy one new coil and try to switch on cylinder that missfire a lot and that not make a difference.

I have a set of perfect working coil packs going cheap if you need any. Just changed mine for new ones just for the sake of it as i was changing the plugs and rocker cover bolts at the same time.

And a set of perfect working plugs with about 12000 miles on them.

Frostie wrote:And a set of perfect working plugs with about 12000 miles on them.

If Felix doesn't want them then give me a PM as id be interested to try and eliminate them as a poss cause for my cold start issues....

You may want to check the main power relay is not failing

Starry wrote:

Frostie wrote:And a set of perfect working plugs with about 12000 miles on them.

If Felix doesn't want them then give me a PM as id be interested to try and eliminate them as a poss cause for my cold start issues....

No probs. I think you are fairly local to me also

Frostie wrote:

Starry wrote:

Frostie wrote:And a set of perfect working plugs with about 12000 miles on them.

If Felix doesn't want them then give me a PM as id be interested to try and eliminate them as a poss cause for my cold start issues....

No probs. I think you are fairly local to me also

I'm in North Bristol just where the M4/M5 cross. As I said, see what Felix says 1st as I do t want to poach them from him...

Ta..

No problem you can take it starry ! I'm long way from you.... I'm from canada ! But thanks again Frostie for the offer!

yorkie wrote:You may want to check the main power relay is not failing

I will check this Yorkie ! it's good idea. I'm in a other forum in USA and two guys have the same idea. I'm gonna replace the two 614 relay.

Hope you get this sorted quickly and out on the road again.

felix2112 wrote:Rw@@dy your RS4 was missfire on every cylinder ??Because i buy one new coil and try to switch on cylinder that missfire a lot and that not make a difference.

It was hard to tell which one was causing the misfire so I just changed them all to be safe