My car pops when you start it
 

Hi,

I am having an issue with my 03 Mustang GT. When you start the car it pops and sounds like it wants to stall. It smells like gas is getting dumped into the exhaust as well. The engine is stock except I have a JLT CAI and the cats are off. The JLT CAI has been on for about 2 years and the cats been off for about 6 years.

I had it to a dealership and the CAM SHAFT sensor code came up. They replaced it but it still does it. When you disconnect the pig tail wire harness from the sensor the popping noise stops but it still smells like gas and the check engine light still is on.

I am not sure what this can be? I had it to a few people and no one know why.

Any suggestions would be greatly appreciated :icon_smile:

Thanks!

call travis lane. number is 803-760-9439 hes one of the best tuners in the carolinas for mustangs. I JUST HAD him build a 2002 gt for me with an f1a with nearly 25lbs of boost. hes the best.

camshaft position sensor can be triggered by an alternator with bad diodes, not sure if this will help you or not. and i'm sure theres more things that can trigger it too. autozone can tell u if the diodes are bad.

In this scenario I don't beleive the alternator can be the cause if the problem alleviates when you disconnect the sensor. There is always a possible the new sensor was bad out of the box this is rare but still happens. When my CPS came on I replaced it and it was fine. There is also a possiblility there is a mechanical problem internally with the cams and the sensor is simply doing its job and triggering the CEL to tell you there is an issue.

Thanks for the advice! I'll start with that first, since it is the least expenseive route to go to.

If you have any other suggestions, please let me know.

Thanks!

95% certain its your alt. bad diodes cause it to interfere with the signal from the cps like mentioned eariler. i had the same problem years ago, the car would backfire and then stall on the first start.

+1 i had this happen to me on my 02 gt. It will show nothing related to the alternator, but i took peoples advice and put a new one on and all was good.

You are very much correct. If you get a new one and it goes out again definitely that.

most likely your air/fuel ratio is off. did the car jump in rmp's when parked at a traffic light or stop sign at all as well??? then again, you could have some fouled sparkplugs from it as well. i don't know for sure but i have a 2002 mustang gt and i was having the same issue. oddly enough the only reason i experienced the same sputtering dilema you are referring to is because my air filter's hose came unseated from my filter's casing and it was sucking alot of air into the system.

I will say it is 100% the Alt. going out. Unplugging the CPS and the problem going away is a dead give away that it's the ALT. When you unplug it the computer goes into default and double sparks (compression stroke and exhaust stroke) since it has no idea which stroke it's on. The Alt. is sending out an electromagnetic field that is disrupting the CPS and causing the computer to spark late in your case with the excess fuel smell.