I replaced the alt on a 06 gt.....now when i start the car it idles up then almost stalls out...my wife will drive it and it idle up/surges really hard....we live a mile from her work and she does'nt have to hit the gas.....car goes all by its self....can anyone please tell me what is wrong..thanks for any response....

 

Is that the only symptom? Could be quite a few things. I'd start out with cleaning the TB and running some fuel system cleaner thru a tank or 2, then go from there.

How many miles on that '06 and when was the last plug replacement? Fuel filter replacement?

A 1 mile drive on a daily basis? Bad, bad bad...

 

we do drive it more but now she is scared to drive it cause it started to stall now....but it does start right up....just idles really rough....don't know only had car for 3yrs.....only put on around 25 thousand miles since we bought it....just getting ready to hit 100 thousand...

 

Agrees with nuke, clean TB, do a new fuel filter and get some CRC MAF cleaner and clean that too. Maybe even change plugs but be careful taking them out, that year, they like to break off in the head, Check threads here for removal procedure if you do it yourself.

 

+1 on all the above. what prompted you to replace the alt? where did you get the new one? could be a bad replacement. the alts on these cars are headaches when they start going bad. how was the car running prior to replacement? more info can get you pointed in the right direction. good luck

 

We need a list of mods for one.

Is the car a stick or auto?

Does it surge only while idleing?

Does warmer weather change it?

Did you get fuel at a place you don't normally get it?

How long has the fuel been in there?

All of the suggestions above are great.

 

Had the same problem with an 06 v6. Cleaned the TB cause it was black. And problem was solved. Might have to replace the IAC valve if the problem keeps up

 

There is no IAC valve on these cars.

 

Unmetered air would cause a surge like that. Only two places that could've really happened given you just replaced the alternator. Intake Hose to Throttle Body OR Throttle Body to Intake Manifold (The rubber o-ring type gasket ).

When putting it all back together did you make 100% the o-ring was seated and not torn?

Recheck those two items and make certain your MAF sensor and Throttle Body wire harnesses are securely connected to their respective parts.

 

My bad, TPS sensor then.