In need of help with my s4 misfires

[Jrdz2120]

Hi,
I am need a little help with my car. I went to the muffler shop today and had my down pipes made into piggies. Everything went smooth with the mods , but now I have multiple codes, P0300 muli miss fire along with P0305,306, and 308 cylinder miss fires. Would having the rear o2 sensors in the stock location cause this. The car is running like crap and I am stumped. I stood there watching everything so nothing would go wrong. Any ideas on what is going on.
Thanks.

[Jrdz2120]

Anyone?

[Jrdz2120]

I cleared all the codes and then took a drive, same thing happens. The car starts to misfire and check engine light flashes. Multiple misfire and cylinders 5,6,7,8 misfires. Would all the coils crap out at the same time?

[Shospeed]

I hade the same issue on mine wen I bought it, the problem was the boot between the MAF & the throttle body had a hole between the ribs that I never saw before replaced it with the one from JHM for a better flow and the issue went away.
On a friend of mines had the same issue and wen I told him about how I found my issue he checked hi and on the same boot were the clamp goes on the throttle body the plastic was kinked and air was getting in there

[staypuft]

I cleared all the codes and then took a drive, same thing happens. The car starts to misfire and check engine light flashes. Multiple misfire and cylinders 5,6,7,8 misfires. Would all the coils crap out at the same time?

This was early signs of timing component failure with my car. I would consider having a full service done, consider the O2 Sensor as well as timing, mine was both. You will save yourself a lot of money in the long run, or at the very least prevent being stranded.

[Jrdz2120]

[headbang]Found the issue. The muffler shop didn't clean out my cat and some of the debris plugged my cat. Go figure.