Cold starts

[grand]

Hello.
1990 Grand Marquis with 5L engine.
When below freezing the engine will start but it is extreemly rough and you must hold the pedal down a little or it will stall. At -5 deg C. it might take 30 seconds to clear and behave normally. At -15 C it might take 4 minutes but it will after that run smoothly. After about 15 minutes of normal operation the engine will begin to race. Nothing I do will stop the racing. I just have to drive like that which is of cource unacceptable.
I assume it is a sensor. Any Ideas?

[fredjacksonsan]

Not sure about which sensor would be doing that, but cold temps will bring out the problems in a vehicle. Might want to have someone do a computer diagnostic on it for you while it's cold, that may give an indication of the problem.

[grand]

I got a code 31 which is AGR valve position sensor voltage too low. I will do some tests on that and let you know what you find out.

[6502dude]

Originally Posted by grand

I got a code 31 which is AGR valve position sensor voltage too low. I will do some tests on that and let you know what you find out.

In addition to EVP (EGR Value Position) sensor, also look for trouble with PFE (Pressure Feeback EGR) sensor and wiring to these sensors.

If you have hard fault, try wiggle test on cabling to sensors.

[owo2]

I have the same problem and here is what I do........

Turn ig. key to on........wait 5 seconds........depress accelerator 1/2 inch......crank engine.........and then hold accelerator for a few moments to keep fast idle up........

Yours stalls like mine does because the fast idle off a 20 degree (or colder) cold start does not engage........if the motor has been off for a few hours, like overnight..........I have a 91 GM with the 5.0.......

[grand]

I have replaced the EVP sensor. There was an improvement but the weather warmed up too much.
I did a restance test on the Coolant temp sensor and it is out of limits at cooler temps. I want some cold weather to test the first fix.