Wuz up everyone? My name Rudy J.I'm New to this forum I just bought a 2003 Mustang GT this saturday.The car was running fine until this morning.When I start her up she cranks then backfires and the engine kills.It takes a couple tries to start her and to get her to stay running I have to rev the engine for a few second after that she runs fine with out any problems what so ever.I took her to the mechanic at the place I bought the car he said it was the camshaft sensor and he replaced it,but the car still does the same thing.I'm thinking the car might need a re-tune.It has a K&N CAI,Exhaust (don't know the brand) with a non catted X-pipe.Thats the only mods I know of.Can anyone tell me what they think might be causing this?
Backfiring Through Exhaust On Start Up
- Thread starter RudyJ
- Start date
squeak93
15 Year Member
Are you getting any codes?
I would of suggested the cam sensor but it just as well can be the crank sensor. Instead of throwing more money at it, go to autozone and have the run the codes, they will do it for free. You could have many different issues and the codes will help narrow it down.
I would of suggested the cam sensor but it just as well can be the crank sensor. Instead of throwing more money at it, go to autozone and have the run the codes, they will do it for free. You could have many different issues and the codes will help narrow it down.
Well I went to Auto Zone.The guy there couldn't pull up the diagnostics on the car.He said It was because I have a bad fuse somewhere.I haven't tried to find it yet.Don't have a way to test the fuses.I changed the camshaft position sensor.It fixed the backfiring problem for the afternoon but the car started doing it again when I tried to leave for work this morning.
I had the same problem with my 02 GT. It didn't throw any codes and it turned out to be the alternator. Once I replaced the alternator, the problem never came back and has been about 20 months. I researched the topic for several months and several people had the same problem and they were the alternator.
I've been preaching about this problem a lot lately. Most people only look at their alternators for charging but they don't know about AC ripple. Bad diodes allow AC voltage through. The Alternator produces volts alternating current but the diodes reduce that down to volts direct current. When diodes fail in an alternator the AC gets through and messes with the computers in your car. The result can be just about anything for problems. Sounds like you have unburnt fuel in your system when you shut down. The computer can allow this when it's confused... like when it gets hit with volts AC. Have the stupid auto tech that is testing your car to check for AC ripple.
Btw, please post up your location. It helps for diagnosing certain aspects of your problem.
Btw, please post up your location. It helps for diagnosing certain aspects of your problem.
flstang65
10 Year Member
wmburns
SN Certified Technician
What about the possible blown fuse mentioned previously in the post? IMO, not being able to talk to the PCM puts you at a real disadvantage. Could cause you to change a lot of good parts when the answer is right there.
At the min, pulling codes from the PCM is an important diagnostic tool.
As for how to check a fuse, my recommendation. Take each one out one a a time. Inspect from the side. If you have a Volt/Ohm meter, Ohm each one out to verify OK.
There are two fuse boxes. The Battery junction box (BJB) under the hood. The centeral junction box (CJB) in the car. For a PCM problem, suggest start with the BJB.
On a side note, is there anyway to track how many problems are actually caused by bad alternator diodes and excessive AC ripple? As other posters have stated, it must be the year of the "ripple".
At the min, pulling codes from the PCM is an important diagnostic tool.
As for how to check a fuse, my recommendation. Take each one out one a a time. Inspect from the side. If you have a Volt/Ohm meter, Ohm each one out to verify OK.
There are two fuse boxes. The Battery junction box (BJB) under the hood. The centeral junction box (CJB) in the car. For a PCM problem, suggest start with the BJB.
On a side note, is there anyway to track how many problems are actually caused by bad alternator diodes and excessive AC ripple? As other posters have stated, it must be the year of the "ripple".
