my 2008 gt is starting with low rpm's then go back up

4.6 mustang123 · 08-17-2009

At least once every 5 starts my car has a hard time idling. It goes low then high. What could it be?

**pcfrisch** · 08-17-2009

Does it return to normal?

TheKurgan · 08-17-2009

Could be a ton of things...process of elimination would start with the maf sensor being unhooked.

AJCaron12 · 08-17-2009

Quote:

Originally Posted by 4.6 mustang123

At least once every 5 starts my car has a hard time idling. It goes low then high. What could it be?

Is your A/C or defroster on when it does this? If so, it is normal.

Back@itagain · 08-17-2009

Welcome aboard! If it isn't affecting performance, blowing smoke, catching on fire or smells of fuel I wouldn't be super concerned with it. Could be any number of things...you should here mine fire up. You would probably feel much better about yours!

4.6 mustang123 · 08-17-2009

wow those were fast replies thanks. and it does return to normal. It only has 13,000 miles on it. i put slp loud mouths on it could that affect it?

10/05gt · 08-17-2009

Not likely. These things have strange personalitys when it comes to how they start and idle. If you had the battery disconnected when you did the muffler deal that will sometimes cause this sort of thing. The engine ECU re-learns throttle commands and positions and a whole bunch of other stuff. Ford calls it adaptive programming or learning. If it returns to normal and runs fine than don't worry about it.

**stlwagon** · 08-18-2009

Does the car have an aftermarket intake & tune?

skstang09 · 08-18-2009

Time for a tune up? Check you plugs.

Back@itagain · 08-18-2009

Quote:

Originally Posted by skstang09

Time for a tune up? Check you plugs.

What???? I would be changing plugs almost daily! The ECU is just searching for its idle just like 10/05gt said. The OP only has 13,000 miles and it sounds like the only mod he has is a set of axle backs. OEM plugs are good for a lot more!

**stlwagon** · 08-18-2009

It could be an ignition coil that's getting a little flaky.

cman · 08-18-2009

You might want to check/clean the throttle body and MAF.

Gretschstang · 08-18-2009

I have been having the same problem for several months (06 GT). Took it into the dealer when the problems started and they found nothing wrong. Took it back with a TSB and replaced my throttle body (car is under warranty still thank god). Fixed the problem.

4.6 mustang123 · 08-18-2009

my throttle body is spotless and my maf sensor is good. Some one mentioned that the previous owner may have tuned it cause that thing by my fuse box had writing on it. He also said "i was missing cardboard behind my maf sensor", but i wouldn't know it that was normal or not.