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Discussion Starter · #1 ·
Hi all this is my first post so bare with me,my s5 recently starting throwing loads of white smoke and and dropped down a cylinder or 2. I got a diagnostic test done and misfiring on 5,6, cylinders then later testing 5,6,7,8 .did all the advisories plugs,swapped coils over faults still with the same bank of cylinders.I did a compression test today ,6,7,8 were all 85,but cylinder 5 was 195.I took the tester off and ran the engine and the fuel was shooting out of the cylinder.enough that the fuel light came on.Am I right in thinking that this is the fuel injecter to this cylinder is broken and not some sensor somewhere else.When I put everything back together there was a pond at the rear of the car.Any help before ordering a injector would be great.Ill take a pic of the codes but obviously the Coil pack was disconnected
 

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Sorry mate no idea but some of our experts will be along soon for sure.....
 

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Audi A5 f5 3.0 TDI Quattro S line S tronic Virtual Cockpit Driving assist pack
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Hi,

You need more than just a basic scanner tool here.

If possible having access to a genuine rosstech cable to see more in-depth code faults would be the way to go to be honest and have live VCDS data logging off the engine too.

The thing here is figuring out if it’s the mechanical side or the electronically side of things that’s causing the misfire/no compression.

As a starter did you clear the codes after the changes you made?

Also seeing if the lambda/mad sensor could also be causing issues! -disconnecting maf sensor to run on base map is a good idea to figure out if it’s electrical or mechanical.

Also to consider if there’s been any type of carbon clean on your car as the 4.2l S5 was renowned for carbon build up due to the nature of the injection system setup which then lead to misfiring issues.

hope you get it resolved!


~Alex
 

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Discussion Starter · #4 ·
Hi,

You need more than just a basic scanner tool here.

If possible having access to a genuine rosstech cable to see more in-depth code faults would be the way to go to be honest and have live VCDS data logging off the engine too.

The thing here is figuring out if it’s the mechanical side or the electronically side of things that’s causing the misfire/no compression.

As a starter did you clear the codes after the changes you made?

Also seeing if the lambda/mad sensor could also be causing issues! -disconnecting maf sensor to run on base map is a good idea to figure out if it’s electrical or mechanical.

Also to consider if there’s been any type of carbon clean on your car as the 4.2l S5 was renowned for carbon build up due to the nature of the injection system setup which then lead to misfiring issues.

hope you get it resolved!


~Alex
No carbon clean done,I need to purchase the rosstech software before going forward.Do you know the best place for this or a link.thanks
 

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Audi A5 f5 3.0 TDI Quattro S line S tronic Virtual Cockpit Driving assist pack
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No carbon clean done,I need to purchase the rosstech software before going forward.Do you know the best place for this or a link.thanks
Age of car, mileage covered also helps with pinpointing other potential misfiring too.

I bought mine from Gendan, as it’s next day delivery and genuine cables.

~Alex
 

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Discussion Starter · #6 ·
2008,70,000 miles covered.will have to get it.I just thought it had to be the injector that was faulty as the fuel it sent into the pot was so extreme.I used over 15 pound of fuel just to do compression test 3 minutes.
 

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Discussion Starter · #7 ·
JUST AN UPDATE,the injector for cylinder no5 was stuck open,fit new and put everything back together.After a few mis fires and coil trouble i have it running without any mis.The only problem I have now is I'm getting dark smoke when giving it some.Will be fine to run it under 3000 revs but anything over and it burns oil.Im thinking have I put everything back together correctly.I did leave a switch off which was a nightmare to get back on with all inlet in position.I did notice slight yellow specles on inside of tail pipes,my thinking it could be the cats with all the fuel going straight out.Doing oil change tomorrow incase of contamination.Any ideas before I take apart????
 
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