Idle speed and Exhaust smoke

[rover3l]

Since changing the fuel pump my fast idle speed after starting seems faster about 1200 - 1300 rpm. Is this to be expected. Today when I started the Q outside temperature in Buffalo about 50F it seemed to emit a lot of whitish / gray smoke. Could have just been a combination of condensation and the fast idle but I fired up another my wifes Chrysler Concorde which had also been sitting overnoght and it seemed to run much cleaner with virtually no smoke.

Does anyone see any problem here?

David

[Q45tech]

Fast idle warm up speed is purely a function of coolant temperature [the hot wax automatic slight opening of the throttle plate] and the added IAC duty cycle to fine tune the speed.

Fuel pressure has little to do with it as long as you have the 34 psi at idle minimum.....................clamping off the return line [a severe test that shouldn't be done more than a few seconds ---really stresses the pump] [raises the 34 psi to 60- 65-70 psi.............increasing the fuel flow by 38% but the ecu just decreases the injector open time to reduce the flow [if the O2 react] otherwise you just get an extremely rich idle mixture and some black smoke till the cats heat up enough to burn this extra fuel.

Doubt the fuel pump caused the change if there was a change, just cooler temperatures after summer.

[rover3l]

Thanks for the reply. It was definitely colder today 50F compared to 65F on the weekend when I changed the pump so maybe as you suggest this is why it ran at a higher RPM on start up

David