1998 Mustang GT won’t stay running.

[Blue2v]

I have a 1998 Ford Mustang GT with a 2005 Crown Vic engine. The car was running flawless when I parked it one night. The next morning I went too start it and it barely starts up. Battery and alternator are good. Once it starts running it runs really rough and will shut off if I touch the throttle at all. It’s almost like it is losing vacuum. Is there any specific places I should be looking for leaks or what is the easiest way to find the leak?

 

[Potomus Pete]

I have a 1998 Ford Mustang GT with a 2005 Crown Vic engine. The car was running flawless when I parked it one night. The next morning I went too start it and it barely starts up. Battery and alternator are good. Once it starts running it runs really rough and will shut off if I touch the throttle at all. It’s almost like it is losing vacuum. Is there any specific places I should be looking for leaks or what is the easiest way to find the leak?

If its so bad the car wont run you should be able to hear it begging for air. I dont think its vacuum . Do the No Start Checklist . Check fuel pressure. Tell us what it was....

 

[wmburns]

+1 on above. Look for a vacuum leak.

It would be handy to know:

• what the fuel pressure is
• What the MAF flow is. Does the MAF flow change during cranking or when the throttle is advanced? Does it make any difference IF the MAF is disconnected?
• What is the PCM operating mode (open or closed loop)?
• What is the battery voltage?

ForScan ODB2 scanner w ELM327 USB

ForScan ODB2 scanner w ELM327 USB

While working on your car have you ever wanted: to find an ODB2 operational PID value (say fuel pressure or MAF)? How about graph a PID value over time? Or compare multiple PID's over time? Access a bi-directional PCM control such as test a...

www.stangnet.com

 

[Jimmy5]

I have a 1998 Ford Mustang GT with a 2005 Crown Vic engine. The car was running flawless when I parked it one night. The next morning I went too start it and it barely starts up. Battery and alternator are good. Once it starts running it runs really rough and will shut off if I touch the throttle at all. It’s almost like it is losing vacuum. Is there any specific places I should be looking for leaks or what is the easiest way to find the leak?

I would try replacing the Throttle body air inlet motor. Probably stuck, if there is any load on motor, even shifting into gear and dies, its the Air inlet motor. If You want You could replace the Throttle position sensor too (its cheap $15).