need some help... my car is putting up constantly a p0420 (cat), P0401 (egr), and a p0300 (random misfire). the car was runing like crap so I took the car to the dealer when the P0300 came up the first time and found out there was a TSB on it. So they reflashed the ecu. did not fix the problem w/performance of car. so they said that my aftermarket part fried the ecu. OK...so i took it to local speed shop. they replaced plugs and dyno tuned. car was running smooth.. but no power. 2 days later cel pops on 3 codes one being the TSB that the dealer will not touch. can anyone help?

current mods.....Safc, k&N, mbc (20psi), buschur 3"tb no cat w/o2 sim, tt, boost and egr gauges. that is it nothhing major

 

might be you fuel controller

 

afc installed properly checked by dealer and 2nd shop who tuned the car.

thanks for suggestion

 

If everything was running fine before your mods, it might be a good idea to disconnect your mods and see where that lands you once you reset. The bulk of what you have listed as 'nothing major' does have an effect on the information your ECU handles, and a lot of it requires wiring. What with all the failed attempts at fixing things as is, it's looking like getting back close to bone stock and re-adding things one by one is your best bet. Unless of course your ECU is really 'fried', and broken beyond repair. Which I sort of doubt.