fast idle and warm up issues

[fgross2006]

I have an 84 LX 5.0 vert.

It has the stock CFI set up. When I start the car cold it cold idles around 2200 rpm and after 45 second or so the choke kicks in and it pulls the idles down to around 1800. In the past, when the car was running right, when I thumped the gas the idle would drop to normal curb idle (550 rpm)

Last summer I started having issues with the idle speed racing even after the car hit full operating temperature. I didn't have time to mess with it last summer but of course the problem is still there after storing for the winter.

Even if I drive the car 10 miles, take it on the highway, drive in stop and go for 45 minutes, the idle stays at 1000 rpm in drive 1500 in park.

I know the procedure for setting curb idle in the CFI set up. I have the printout from Ford racing. I did reset the curb idle last summer and although I got it set right that day, the next day the car went right back to idle racing even after reaching operating temp. I noticed that if I shut the car off, like going into 7-11 for something, come back and suddenly the idle is right where its supposed to be when I restart the car.

I have a metered vacuum dashpot controlled by the ECM. I am 1005 sure the ECM isnt sending a signal to engage vacuum to the dashpot and thats why the fast idle is there. I know the vacuum solenoids work because the choke kickoff vacuum is from the same vacuum lines the dashpot gets vacuum from. And the fact that the dashpot engages after I restart the car i know the vacuum is good.

So, is it the ECM not telling the solenoid to apply vacuum to the dashpot or the solenoid itself malfunctioning?

Just to list, I put NOS solenoids on the whole vacuum solenoid cluster a few years ago. All Genuine Motorcraft. The Dashpot was NOS Motorcraft replacement about 4 years ago too. the ECM is a refurb.

[fgross2006]

Although I didnt get any takers on this one I think I solved it today. The car started behaving this way last summer but I didnt take time to look it over. Today I started it cold, air cleaner off and checked out the choke function. The choke spring had tension and the choke's vacuum pulloff worked like its supposed to after around 45 seconds. The issue at had was the idle wasn't kicking down to correct idle after thumping the gas pedal.

I noticed the cam behind the choke spring appeared to be stuck. When i moved it manually the idle dropped so i zapped it (and all linkages) with WD40 and the idles was near perfect. Probably a few RPMs low in fact.

[KevinK]

Mine does the same thing after sitting for a few weeks. Its gets better when used more often.