WTF? Please help. Bad misfire, Brakes come and go Happened to you?

[SIKAudi]

OK so here is what is happening so far, and if you guys have any insight it would be greatly appreciated..... Bad misfire and very rough idle, surges, only once did the engine light flash otherwise it is always on, shifting irregular as to not have enough or too much vacuum, limped home and the brake pedal stiffens up occasionally but it is extremely difficult to stop (twice in 7.5 miles), smells like it is running really rich. Haven't run codes yet but if anyone of you guys had this happen could you shed some light on where to start. By the way vacuum hoses and plugs have been checked good and or replaced when this started about eight months ago and has been running like a champ until this morning in fact late last night she ran awesome. Thanks guys

[ben916]

Bad gas? Fuel filter?
I was just going say plugs but you got that covered...
What about air filters?

I do remember AUDI5000csqt-xyzpdq had a vacuum line crack to the brake booster and he had the hard pedal "oh $hit" moments...

[SIKAudi]

covered the bad gas problem with some 100 oct last time. filters are clean, fuel filter? would that cause all the issues I see, fuel press. regulator maybe guess i will check codes and trouble shoot one component at a time......ArrrGGGGhhhh!!!! Thanks!

[ben916]

covered the bad gas problem with some 100 oct last time. filters are clean, fuel filter? would that cause all the issues I see, fuel press. regulator maybe guess i will check codes and trouble shoot one component at a time......ArrrGGGGhhhh!!!! Thanks!

the brake "hardness" would be caused by the lack of vacuum to the booster because the engine is not generating enough vacuum itself because it is misfiring/etc...
What about coil packs???

Also... OEM plugs or something else?

[SIKAudi]

was reading some threads about that, got the recall info in the mail on my R32 but nothing on the RS, I will check those probably get back to you guys later tonight need to finish the R32 will be done today doing the last minute finishes after turbo charging it so timing couldn't be better can swat vehicles. stay tuned let you know tomorrow what codes come up with and get some parts if in stock.....

[p3u]

You have the exact same problem I did 2 months ago. Turned out bad secondary air pump, which is why the brakes come and go. It's not a fun job, I don't recomend doing it on your own unless your savy with the beast, took me 20 hours....

Dealership can replace it for around 1500-2000.

Try this, take the airbox off, turn on the car and listen to the motor and spot where the sound is coming from, should hear it hiss. If it sounds like from under the manifold, air pump.

[snoopra]

Could also be defective MAF's

[p3u]

Could also be defective MAF's

But if the MAFS were bad the brakes would not be affected.

[JSRS6]

Check your O2 sensor plugs. When i got mine back friday after driving for about 30 minutes, i started feeling the same thing. I went to autozone, grabbed their obd-2 real quick and came up with bank 1 and 2 were lean, and misfires on all cylinders on bank 2 i believe. Should have taken a pic of the screen, but its too late now. After clearing the codes i decided to check under the hood to see if anything had worked itself loose. I dont know if it happened during the collision, but my o2 sensor plugs had come loose from the firewall. i unplugged them both and plugged them back in and didnt get anything again after that ;-)

[DHall1]

Right here folks

http://www.rs6.com/showthread.php/20...=brake+booster

I do remember AUDI5000csqt-xyzpdq had a vacuum line crack to the brake booster and he had the hard pedal "oh $hit" moments...

[hahnmgh63]

P3U, what do you mean about under the intake manifold? My secondary airpump mounts on the passenger side on a bracket next to the firewall, just about on top of the passenger side front wheel.

[1sadavant]

Sounds like you have a vacuum leak, your symptoms of brakes going and the misfires are classic. Are you able to vacuum/pressure test the car?

[p3u]

P3U, what do you mean about under the intake manifold? My secondary airpump mounts on the passenger side on a bracket next to the firewall, just about on top of the passenger side front wheel.

My mistake, I meant the suction jet pump. I was thinking the wrong name for the part.

[p3u]

Heres my post on it, when I replace the part in question. PITA!!!

http://www.rs6.com/showthread.php/20...nds?highlight=

[p3u]

Heres some pictures to show what part I'm referring to and its location.

Notice how the pump separated? On the new version if the part there is a lip that goes over the back end to prevent this type of failure from happening.



Here is the part with numbered connection points and where is goes on the intake manifold/engine







I'll bet you one of Dhall's famous chicken diners this is the problem

[ben916]

you are a brave man...

[JRS-RS6]

p3u didn't I warn you on another thread not to temp the trolls I mean smoking monkeys. Instead of chicken you might end up eating crow. Certainly your situation could apply here, the symptoms all point to a hugh vacuum leak somewhere close to or possibly in the brake booster with the car smelling rich because it is trying to save itself from melt down by increasing the fueling.

[SIKAudi]

OK! Sorry guys if you were wondering what has happened. I have been away for a while on leave, got married and stuff. So back to the original prob and am tired or chasing down all the maintenence issue. Now they are all taken care of. Still have the missfires and vacuum issue but am down to one final code "P1479 Brake boost vacuum system mechanical failure implausable signal-intermittent." So I spoke directly to RS tech and friend and although the code calls out for the brake booster, 9 times out of 10 its a vacuum line coming off the pump and is a pain to fix but a lot cheaper. We will investigate this week some time and I will keep you all updated. Keeping my fingers crossed..... And thanks!