studdering/ backfire on a 2003 ls v6

[karolpl2004]

it started to happen today. when i drive, then slow down, and accelerate again, the car studders and backfires. i have read several forums regarding this but cannot find any answers. is it the transmission? it seems like the car just does not know what gear to shift into.. i doubt its a misfire since no codes are appearing and MIL is off all the time. how much does a dealer charge nowdays for a tranny reprogram? or if thats not the problem, then whats causing this?

 

[1LoudLS]

well you really need to know if it is a misfire or a backfire.

misfires rarely ever throw a code with the LS.

what you are describing sounds like most misfires in an LS.

 

[karolpl2004]

i ran various test with scan tool and none came up with misfire.

 

[joegr]

i ran various test with scan tool and none came up with misfire.

Yes, rarely does the PCM detect the misfires from marginal coils. That doesn't mean it isn't happening, it is.

 

[1LoudLS]

i ran various test with scan tool and none came up with misfire.

so then since you ruled out a misfire, so then your sure it was a backfire. well it could be that your car is sparking at way the wrong time (only some of the time) or that the timing on some of the valves is way off time (only some of the time). that sounds like its going to get expensive real quick.



or you could just have a coil on its way out and as mentioned above

misfires rarely ever throw a code with the LS.

rarely does the PCM detect the misfires from marginal coils.

 

[karolpl2004]

but when i drive it agressively, it doesnt do it.

 

[joegr]

but when i drive it agressively, it doesnt do it.

Sounds like marginal coil misfire to me. (That's the way mine was.)

 

[1LoudLS]

but when i drive it agressively, it doesnt do it.

that is exactly how my car acted when a coil started to go bad on my car (three times now)

to me (with the information giving), it sounds like you have a coil that is just starting to go bad (marginal, as Joe said) , as it gets worse, it will happen more often and be more noticeable. i wouldn't wait too long before getting it taken care of, every time it misfires, the car is dumping some unburned fuel out of the motor, this will cause damage to the cats. if it ever gets bad enough to throw a blinking CEL, stop driving the car right away.

 

[karolpl2004]

well that sucks. changing the coils is a lot of work it looks like. gotta take off the intake manifold and all.. i thought v6 models dont have this problem!!!

 

[LS4me]

well that sucks. changing the coils is a lot of work it looks like. gotta take off the intake manifold and all.. i thought v6 models dont have this problem!!!

EVERY car with a COP will eventually have this "problem".

 

[1LoudLS]

i thought v6 models dont have this problem!!!

not as often, but it does still happen. we just have more things that can cause coil issues that go wrong.

 

[BlackLS06]

Changing cops beats having to screw with distributor caps and points and that single ignition coil than can shock the :q:q:q:q outta you.

 

[LS4me]

Changing cops beats having to screw with distributor caps and points and that single ignition coil than can shock the :q:q:q:q outta you.

Ahhhhhh.... The joys of setting the points every 12K miles. Having to buy a new cap, rotor and usually wires also every ~12K miles.

 

[TooManyToys]

And I have a ear to ear grin every time I do it. X2 The wires last more like 60-75k.

 

[LS4me]

And I have a ear to ear grin every time I do it. X2 The wires last more like 60-75k.

My first car was a '65 (actually, '64 1/2) Mustang; 225HP 289, 4 spd, no power anything. I sold it when I got married as my wife didn't have her license yet and had no idea how to drive a stick. She asks me every now and then if I miss that car. I tell her not really. That thing went straight very well; turning and stopping could always get interesting.

It was fun, but I enjoy my LS more.