HELP!! Starts idles but dies when put into gear

[JLstang351]

2001 GT with minor bolt ons. exhaust, intake, 3.73, predator tuner. Car has a auto trans. 147k miles.

Last few weeks its been cold here in GA and I always like to let my vehicles warm up. Well It starts and idles perfect soon as you put it into reverse or drive it dies. First few times it happened I just let the car sit and come back to it hours later and it would do fine. Last few times when it dies i just give it some gas and it hesitates a little but eventually starts. When it does start it looks like a diesel cranking in the cold (white smoke). I replaced the fuel filter last night but it did it again this evening. morning was fine, guess cause it stays in the garage overnight. car pulls great so dont think its starving for fuel and it idles perfect so I wouldnt think its the IAC either. PLEASE HELP!

 

[wmburns]

Start by cleaning the MAF.

The things that cause a slow idle are:

Vacuum leak between the MAF and the IAC. Note, when the weather is cold, any vacuum leak will be made worse by the dense cold air.

Bad IAC.

Weak cylinder (ignition).

Weak cylinder (base engine).

Of course this could be a case of the cold affecting the automatic transmission. IE the cold ATF places more load on the motor. When the transmission warms up, the problem goes away.

I would also check the engine coolant temperature (ECT) sensor and Input Air temperature (IAT) sensor for reasonable values.

 

[trinity_gt]

In addition to wmburns' excellent suggestions:

- if you've got a scan tool, make sure the P/N (park/neutral) switch is functioning properly.
- with the engine idling, unplug the IAC connector and observe what happens.
- what happens to the engine RPM if you turn on the A/C or the cooling fan comes on?

 

[97gtstang01]

Was this ever resolved?having same problem with a buddies ride

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