Back Fire on Start?

[KarmaKid]

Whenever I start my 2002 GT, 70% of the time it seems to backfire. I wait 2 seconds and it starts with no problem. On the first attempt, it turns over begins to start followed by a pop or two pops out of the exhaust, then nothing. The only mods I have at the moment are BBK off road x-pipe with MIL eliminators and subframe connectors ( not that the connectors would have anything to do with it ) I live in MA and it the temp started to change about a month and a 1/2 ago, which ironicly is when this issue started? It does not matter if the engine is cold or warm. I use 89 octane gas. I have had the vehicle since 09/09/06. This issue did not start until the weather changed. No other symptons that I can see. Weather related? un-burnt fuel from no cat's? Stuck valve?

P.S. Happy Holidays!

 

[04YELLOWGT]

If it was only on cold starts Id say it would just be somewhat of a tune problem. My car did something like this but was after my SC and MPH Tune, and my half brother's car did this when his 02 was stock. With mine I had more fuel added on start up in the tune and on his he took it to Ford and fixed his, dont know how though.

 

[Skidawg]

The '02's have a hot starting issue. Some of them will "backfire" a bit at startup one time. After that, the issue disappears.

Related or not, my cam position sensor was out of whack. I had it replaced and have not had the issue since.

I know it's been discussed before. Hopefully, someone else will remember more, or it will come up in a search. Good luck!

 

[jtroush2002]

exhaust leak maybe?

quote:
"Engines that consume oil at a high rate will deposit high levels of phosphorus on the catalyst and reduce the catalyst efficiency"
causing a backfire

 

[KarmaKid]

Thanks for the info!

If I fgiure it out, I wil update.

 

[Brute03]

is the CEL on? i know my car used to do the same thing when i had that pesky "cam position sensor malfunction" code

 

[Smokeurhonda]

Sounds like a triggering device problem. Check cam and crank sensors.

 

[KarmaKid]

Sounds like a triggering device problem. Check cam and crank sensors.

Looks like you were right. I was driving around last night and my engine light came on. Luckily I had my Excalibrator in the car and pulled the cam sens code. Getting me a new cam sensor today.

 

[four six]

keep us updated

 

[KarmaKid]

Grrrrrrr....

Ok, so it was Sunday and the Ford dealership was closed, therefore I ended up at Autozone for the cam sensor. Wells manufactured I believe. Easy swap, just slightly remove the power steering pump, unscrew, remove then replace. Check engine light was gone upon first start then reared its ugly face about 2 days later. Still getting the backfire/pop upon initial turn of the key, but only intermittently. I have read in a couple other threads that peeps have replaced the alternator because their mechanics said the bad alternator was electricaly disturbing the cam sensor. Welllllll, yesterday I left my running lights/fog lights on which killed the battery. I tried popping the clutch and starting a few times with no luck. Today I tried jumoing the stang 4 times. Each time it would run for a minute or two then die. So I'm assuming it ran on the teeny tiny charge from the jump, then died because the alternators *****. So I'm going to pull both the alternator and the battery and have each one tested today. Fun Fun Fun.

 

[KarmaKid]

Fixed!!

well, replaced the alternator with a new one. It seems to have fixed the cam sensor issue and the backfire issue on initial start. What a pita this was to figure out.

 

[stangGT97]

well, replaced the alternator with a new one. It seems to have fixed the cam sensor issue and the backfire issue on initial start. What a pita this was to figure out.

Sorry I couldn't contribute to help you, but thanks for keeping us updated and I'm glad to see it's fixed