2000 Grand Marquis cold start problem

[L.T.]

When I first start the car in the mourning it won't Idle, so I hold the throttle open until I hear a pop (like a vacuum diaphragm sucking in) after that it idles fine and runs good. After the engine cools back to cold state the problems comes back. I do not have the problem when the engine is hot.
My brother told me he was having the same problem with his Ford Thunderbird. Both automobiles have the 4.6 v8.
It seems to be a common problem.
I have changed the fuel filter, idle air motor, fuel pressure regulator.
I changed the fuel pressure regulator because the regulator would not hold pressure after the engine was turned off. It now holds 40 psi for an extended period of time. It also pressurizes to 40 psi when activated with the key it run position. It is now getting worse.
This problem is intermittent some time it starts and runs fine at cold start.
I have been chasing this problem for almost a year.
Has anybody else had this problem and found out what causes it.

I have fixed this problem!
It is the "idle air motor" it regulates the air flow to the throttle body. I fixed it buy soaking the mechanical end of the part in carberator cleaner.
Do NOT to put the electrical end in the cleaner.
The car has it's horsepower back and starts and idles great.
thanks for all suggestions.

Tom

[jimmytroanoke]

Originally Posted by L.T.

When I first start the car in the mourning it won't Idle, so I hold the throttle open until I hear a pop (like a vacuum diaphragm sucking in) after that it idles fine and runs good. After the engine cools back to cold state the problems comes back. I do not have the problem when the engine is hot.
My brother told me he was having the same problem with his Ford Thunderbird. Both automobiles have the 4.6 v8.
It seems to be a common problem.
I have changed the fuel filter, idle air motor, fuel pressure regulator.
I changed the fuel pressure regulator because the regulator would not hold pressure after the engine was turned off. It now holds 40 psi for an extended period of time. It also pressurizes to 40 psi when activated with the key it run position. It is now getting worse.
This problem is intermittent some time it starts and runs fine at cold start.
I have been chasing this problem for almost a year.
Has anybody else had this problem and found out what causes it.

Try to find the source fo this vacuum diaphram thing. Maybe a sticking brake booster? Disconnect and plug the vacuum hose at the booster before staring the car and see if that makes a difference. Could also be a bad vacuum reservoir for the HVAC. Disconnect and plug that and see if that makes a difference. Intermittents can be a bitch though! good luck!