I was on interstate when i needed to pass someone took it to 85mph in 2nd when my check engine light starts flashing.I back off and it goes away after a min,So i baby it home seems to be fine.Well today while on way to work i got on it merging into traffic and same thing light starts flshing then on steady.but this time i can here it knocking and bad. So i scan code it's po300 random mutiple engine misfires,and i can here it knocking on drivers side,so i go under it and it sounds like it's coming from my drivers side cat, and not engine.So i tap on the cat with screwdriver and knock goes away for a min then comes back im totally stumped.I checked all wires nothing burnt checked connections to coil pack and plug's all good there 2.My mods are in my sig and i havent sprayed for over a month now so take that out of the equation.It's still under warrenty but if it is the cat do yu think they will evan cover it?or something worse.I can remove all mods except headers and exhaust and tune.Any input would be great thx.

 

Flashing SES light is an indication of the mis fire monitor. Get it hooked up to a scanner and check your misfire datastream.

 

What plugs are you running? If it's some NGK TR55's or colder, you may try putting some new ones in. If that doesn't work, try the plug wires.

That should get you started in the right direction.

 

if they are the factory cats, they will be covered by a lot longer federal emissions warranty, it will be up the the dealership to decide if your mods have in some way voided the warranty.

take it and see what they do.

flashing SES is a indication of imediate cat damage, usually from a very rich condition.

good luck.

 

Thank's for replys ya im stumped replaced plugs and wires yesterday put in tr55 gapped at.60 and msd wires.Still have issues at 4500RPMS ses light flashes and breaks up stops pulling and sounds like golf ***** in coffee can,as soon as i back off its goes out how fricken weird is that. i cant figure out why it would be so rich, my gas mileage is crap and my oil smells like gas.I havent changed a thing in last 12000 miles evrything in my sig has been there but im pretty sure it my drivers side cat i took long screwdriver and put it to my ear,on header on block and on cat and its the cat.Im taking to dealer on tue,i dont expect much im sure they will say it the cat, but i imagine they just replace the the whole y pipe to make it simple and with my azsm lt none of that is left flanges welded like 1/4 inch before colectors.So if they hook me up sweet but i aint counting on it.I have no scan equipment so why im taking it in im sure thell flash my comp to just because

 

you have bad plug wires or a bad spark plug that is why it blinks and will not go any faster we have this happen all of the time at our shop. check the wires with a multimeter they shouldnt be over 2500 ohms each one and check your spark plugs

 

I allrdy replaced plugs and wires yesterday still there.Went with msd and ngktr55 gapped at .60

 

you might have a bad coil pack you need to go to a shop witha tech2 scanner or snap on scanner and see what cylinder or cylinders you are getting the missfire and start from that cylinder and you will solve this alot quicker. believe me it gets to be a pain in the butt.

 

Close the gap up on those plugs to about 50 thou and see if that helps.

 

i hope that your piston is ok,, and that sound you hear in your cat isnt a piece of debri from a broken part.