I just bought a act x3 tuner and put on a CAI. When I was pulling up to a line of traffic I stopped and then all of a sudden the car lurched forward and rear ended the car in front me. Has any body else had this problem. I'm driving a 2006 Mustang GT 4.6

 

did you stall and thats why it lurched forward?

 

With just the info you've given us I can safely assume you stopped too close behind the car in front of you, I would stop while I can still see the tires of the car ahead of me. Secondly when you press on the brakes, press hard this way if the car does lurch it won't go far and certainly not hit the car ahead of you.

I know it may seem that I'm being a bit of a smart a** but I don't know how old you are or how much experience you have driving. Is your car an automatic or manual?

I have a FRPP CAI and Diablosport inTune running the custom 93 octane tune and have never had any lurching. It does at times and mostly in reverse have the tendency to bolt when I press the gas pedal.

Give us a little more info so we can be of more help.

 

...and this is why I put mine in neutral at a light and hold the brake. Even in an auto. Because once in a '66 Thunderbird, I accidentally came off the brake and stomped the throttle full on... and JUST stopped short of the next car. My bad. (For those of you who would say different, I can put it in gear and get outta there in a pretty dang quick hurry... and if I can't? That's what insurance is for on the car, and life will be what it will be, but at least I ain't slamming through people when the car says "I'M OUTTA HERE DUDES!!!")

In any event, on a 2006 Mustang 4.6, there is a *possible* issue with the throttle pedal sending a bad signal, as would be true of ANY throttle pedal, TBW or hard linked, on any car. I've not experienced this myself on mine though... But my dad did on his '66 Tbird when he stomped it, the motor shifted due to bad motor mounts, and stuck the throttle full on... right through the garage before he could stop the car.

He also, on his '64 Falcon, while going into his garage (and I happened to be there this time) had a full throttle happen. Twice to one dude, I know, right? Luckily, he had used a bunch of plywood to help the Falcon clear his garage's front lip with his exhaust, so when he went full on throttle, they shot out from under the car, and he WAS able to just turn the car off before he ran it through the back of THAT garage.

Lucky man that. Oh, the cause... the electronic cruise control he'd put on it? Yeah, it went completely NUTS and commanded full throttle all the time. Nothing wrong with the linkage ('95 Mustang 5.0 in that car, correct throttle body for it too.)

Anyway, just saying a full throttle situation could happen *any time* and you need to be prepared for it. They are made by humans, and aren't perfect. Ever. And when you mess with it, even better chances.

It is also *possible* that the tune could have messed things up, but not likely. Unless your tune is very very unique, others have it and aren't experiencing this.

When's the last time you cleaned your throttle body, and reset your computer? Perhaps that's it.

Did you change anything recently that might be related? Perhaps spark plugs?

And all the other things listed above me.

 

I know on my 05 GT with manual trans the throttle is very hard to control until the pcm goes into "closed loop". I informed Brenspeed and had then send me a new tune with slightly more throttle control. It's still sensitive before "closed loop" but has slightly better driver control once the engine is warm.

You might try checking over all the mods you've done for correct installation, eg. loose hose connections, and reinstall the tune again. I would definitely call the xcal3 supplier you bought from, inform of mods done and inquire for safety purposes. They may be of better help.