Misfire warnings won't go away in sport mode

[StealthRS4]

Hello all,
New to the group but just bought an 08 RS4 and loving it. However, I started getting Check Engine Lights more and more frequently soon after the purchase. The dealer I bought it from has been great and covered everything we have tried so far but still having issue. Had a carbon cleaning done (and new plugs while he was in there). Still getting lights. Just had 8 new coil packs installed and it seemed better but 40 miles later, multiple misfires again. I HAVE noticed that I usually drive in the SPORT mode and that is when most of these occur. The mechanics test driving it have not been using the sport mode. Why would this run go perfectly in normal mode but quickly misfire in sport? ECUs? Running out of ideas.
Thanks in advance for any advice you can give me.

[NJMAudiRS4]

It seems to suggest an ecu style error, has it been remapped ? Could be a dodgy or spurious map. Possible manifold issues ? What about MAF sensor ?

Have you tried speaking to Doug at MRC in Banbury, maybe he can shed some light

[StealthRS4]

Unfortunately I am in the US (You guys seemed to know this car well), so I can't take it to Doug. According to the service history it had a remapping done early in it's life at an Audi dealership. I agree that it seems to run fine and have not lights come on in normal mode makes me think that it is ECU also. It actually runs great in sport mode too but keeps sensing misfires. It did run a little rougher occasionally when it was damp out but I think the new coil packs solved that. The mechanic checked the O2 sensors and the MAF sensor and said they looked clean and functioned correctly. The misfires usually show up on both banks but I need more testing as that was before the new coil packs.

[R1RS4]

Hi there, and welcome

Does not sound like it an Audi dealer?

Have they checked the vacuum system?

Do you have rear exhaust valves? As these are operated via part of the vac system

You need to purchase a VCDS kit from Ross tech, (USA) and you can run a simple fault check then list on here , and there's many a guy on here that are better qualified than most dealers and they will point you in the right direction

Also you need to get a photo of your car up on the site or your in for some stick

[StealthRS4]

THey looked over the vacuum system and it seemed good. I definitely hear the exhaust change when I switch to sport. I will look into the VCDS kit you mentioned. I have a Bluetooth ODB2 sensor plugged in and I get the Check Engine Lights on my phone. Was getting Multiple random misfires on multiple cylinders and individual random misfires on each cylinder. With the new coil packs installed yesterday I have only gotten them once on Cly 4 and 7.

[NJMAudiRS4]

You could still contact Doug at MRC, send him an email or give him a call on the old telephone.
Misfires tend to through up error codes, have you had them checked these can point you in the general direction of the cause of the fault.

I had an issue relating to the ecu, it put my car into limp mode, couldn't understand why, even sent the ecus off to be checked independently, they both came back with no issues, whilst refitting the the guy who checked the ecus found a voltage charge, which was odd as the battery wasn't connected, it turned out to be an earth cable off the wiring loom from the second ecu, it attaches to the bottom of the negative/ earth point where you attach jump leads.

Oh and FON welcome to the site

[R1RS4]

THey looked over the vacuum system and it seemed good. I definitely hear the exhaust change when I switch to sport. I will look into the VCDS kit you mentioned. I have a Bluetooth ODB2 sensor plugged in and I get the Check Engine Lights on my phone. Was getting Multiple random misfires on multiple cylinders and individual random misfires on each cylinder. With the new coil packs installed yesterday I have only gotten them once on Cly 4 and 7.

OBD' Bluetooth plug in's are very basic, the vcds will give you detail your after

Good investment the vcds and you can sell on if you part with the car

[StealthRS4]

Good to know. I will investigate and purchase one. Thanks for the info.