hey i need some help, i went to my car this afternoon and when i strarted it up i noticed that it was missfiring really bad. i was able to drive it home but there was a big power loss. i have a 99 maxima supercharged, cattman headers and catback exhuast and all the stock parts that came with the stillen kit. need help as to what i need to look for!!!
also when i give it gas the exhaust sounds like a WRX, and u can hear it backfiring really bad.....dont know if this helps!!!
thanks!!!!!

 

Any codes ??
99's are notorious for Coil problems but dont jump to conclusions till you run it for any codes.

-matt

 

sounds like a fuel problem. check the codes in the ecu if you can and let us know. do you have a exhaust leak? is your exhaust smoking? could be a leaky fuel injector. i had the same problem and it was an leaky injector and a exhaust leak. my car was just like yours it sounds like a wrx and i lost boost. when i would give it full throttle i would see like 3psi. did you notice any boost lost?

 

Sounds like a leaky injector, might want to check that. Check the plugs for fouling, if it's been doing it you'll know.

 

You can easily check the coils while the car is on and misfiring by just unplugging them(one at a time to see if it gets worse). Check those out. 2 of mine have gone bad so far.

DF

 

kinda, sometimes. You can have coils that work fine at idle and light load but then misfire when you give it more throttle...

 

well i checked my codes and 0304 came up and i changed my knock sensor, still the same problem is happening, does anyone have any clue what this could be, now when i check my codes the only thing that comes up is 0505, which is normal

 

My guess would be a Coil Problem. Knock sensor wont cause missfiring at all

-matt

 

is there a way of checking without having to replace them all?

 

If you have a rough idle because of a bad coil pack, and you should if indeed one is completely dead. Then disconnect each one and listen for a change in idle quality. When disconnecting one there is no change then that coil pack is bad

 

thanks im gonna have to try that

 

My hunch is coilpacks or sparkplugs. Are you running one step colder plugs? What gap? Mess with your fuel injectors lately? Clogged fuel filter? Failing fuel pump?

 

yeah im going to replace my plugs today and see what happens. im running normal plugs, and everything stock or stock from the stillen kit

 

I believe if you bring your car to autozone they can test the coils. I used to work there and tested them myself via the testing books they should have.

Not sure if they'll even know what you're talking about though. Give it a try though (they'll do it for free if they are able to).

DF

 

When I had coilpack issues, I found that testing them was inconclusive. I tried what the FSM recommends, Haynes, and Chiltons. 3 different methods, 3 different results. Very misleading results. They appeared to be fine for the most part. I swapped coils with Ptatohed for a day and determined that I had full power with his coils. I bought new coils and my car has been good ever since.

 

when u check each coil pack by disconnecting them do u leave the car running and unplug one at a time or do u turn it off and switch back and forth?

 

fixed was a bad coil....thanks for all the help!