TIM COSTA

As the title says, I have a 2001 2.7 that back fires thru the intake A LOT when cold. When the car heats up it still does it just not as bad. MAF has been changed along with ECU, Alarm module and lots of other stuff. Any ideas???

Macster

Ideas? Yes, get an OBDII code reader/data viewer and use it to check intake air and coolant temperature at engine start. Since you already replaced the MAF which provides intake air temperature the next suspect is the coolant sensor is reading wrong, reporting the coolant temperature too hot, and the engine controller is not feeding a rich enough mixture to the engine when you start the engine cold.

However, that the backfires occur when the engine is hot could be due to an intake air leak. Backfires through the intake most often (but not always) are due to a too lean mixture. Check the oil filler tube cap for a leak. The oil filler tube itself can crack/split and leak as well. Can't recall ever reading about one leaking so bad as to cause backfires, though, cold or hot.

Then a bad AOS could also be a suspect.

And what's lots of other stuff refer to?

Has the intake been messed with recently? Could someone have been at the engine and left a vacuum line loose? Or could one have broken and not been noticed? Were the coils/plugs changed recently?

Last thing touched is always suspect so the last thing serviced, like plugs/coils, could be a clue.

Sincerely,

Macster.