1994 Mercury Cougar irratic idling

ONESHILOAH

MEMBER
1994 MERCURY COUGAR

Engine problem
1994 Mercury Cougar V8 Two Wheel Drive Automatic 110XXX miles

I have a 1994 Mercury Cougar XR7 w/ a V8 4.6l when I start it it stalls, after restarting it while holding down the gas alittle it will start and idle weirdly (between 500rmp to 1000rpm when cold) after it heats up it will still do the same, I changed the egr position/flow sensor and the mechanic told me that the egr was good but the the egr vacuum line may be blocked w/ crud and needs to be cleaned, heres my question, could the idle speed sensor be bad if theres irratic idling and stalling when first started and how to clean the vacuum passages for the egr. Is there a more easier way to get to the idle speed sensor and the egr pathways. Thanks

1 Reply

MERLIN2021

MECHANIC
17,250 POSTS

The idle air control or bypass, is bolted to the side of the throttlebody, remove it and clean it with a ford approved cleaning solution. Ford caots thier throttles with teflon, so this important. Clean the throttlebody while your in there. To clean EGR passages, remove the egr, use a piece of steel coathanger, push it all the way thru to the throttle plate, you will see it come out there. Put everthing back together, if you see an improvement but still not great replace the idle air control valve. And test for vacuum leaks.
Get a can of spray gumout, spray the vac lines and maniflod area, when the idle changes, youve found the leak! You want the engine running and spray on the outside but do direct the stream onto the hoses, if it is a vacuum leak, the engine idle will change speed, then you have detected a leak, repair the vacuum leak and see how it runs!