This is my first post i tried searching didn't come up with any thing may not of done it right but im having a problem with my 03 gt. The service engine soon light keeps comming on and setting the code P0340 for the cam postion sensor. also when starting the car it cranks for a second then back fires and dies. If i give it gas while trying to start car will usually start up with no problems.I already put a new cam position sensor in the car from ford cleared the code and it came back after about a half hour of driving. My car has a bbk cold air intake, diablo programer, bbk x pipe no cats, and aflowmaster exahust system with the tail pipes removed. I was told i may have a problem with not enough back pressure but i have been running the car like this for 2 years with no other problems. any info would be appriciated thanks.

 

i think the simplest thing to do would be a compression check, that should show if the cam is degreed incorrectly. I've never heard of the chain jumping a tooth but i guess it is a possibility.

exhaust gas back pressure has no affect on cam position

 

More then likely your alt, is going bad. Don't ask me why it screws with your cam sensor something about a magnetic field or something. Pull your alt. off and go get it tested.

 

Oxford is right. It tends to be the regulator in the alternator that goes bad and causes this.

 

The shop manual says that amoung other things:[/align][/align]A bad regulator could indeed pass a whole bunch of EMI and RFI into the system wiring...[/align][/align]

 

Thanks for the help ill check the alternator tonight when i go into work. I never would of thought of that being the cause.

 

Good call on the altinator checked it when i got to work and sure enough, it was bad. I'm still having problems with the car wanting to back fire slightly not as bad. I reinstalled my factory tune and didn't seem to have a problem the rest of the day. Just curious if anybody might have an idea with why it might be doing that.

 

i have also had this happen to me, just got a check engine light, and it was that p340 thing. i changed the sensor, it cleared it, but only to come back the next day. i still havent pulled my alt, though i suspect it is bad. ive had issues with it prior then getting these codes. i`ll update when i get the alt checked. thanks

 

crazy, i have never heard of that actually happening you see it in shop manuals allthe time but completely disregard it cuz it never seems to be the issue, good info! good luck

 

Listen to this guy he knows what hes talking about.