3.7v6 idle problems
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Senior User
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3.7v6 idle problems
Hey all... I'm at a loss.. I have a 2012 extended cab 3.7v6 4x4.. it's been to the dealer a few times for an annoying idle problem. When I am stopped at a light or stop sign, the truck shakes badly. Take your foot off the brake and the idle smooths out. Ford says there is nothing wrong after 2 visits. When summer weather was 100 degrees plus it ran like a top! Even now on a cold start it runs great.. smooth idle.. but as soon as it warms up the horrible idle is back.. does this sound like an EGR valve? I would think the dealership would have checked that.. they said they ran about 80 different tests.. and it passed them all. Any thoughts? Does the EGR sound like it could solve it?
Fleet Owner
Joined: Mar 2012
Posts: 26,199
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From: Near Cal. Avenue
It would seem to be brake booster vacuum related? To quickly test your booster warm up motor, shut off motor, apply the brakes several times until the booster is depleted of vacuum boost. Apply the brake pedal to the normal braking position, start the motor, pedal should move downward as the booster builds up boost, this indicated it is working correctly. If it doesn't it is malfing and replace it. The EGR thing doesn't exist on this motor, the valve variable timing is used to reduce ozone emmissions. If the timing is off you should get a code I believe. It sounds to be vacuum related problem and will probably rapidly worsen. I wouldn't run out into the desert without a gallon of water handy.
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Senior User
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Well.. I tried the brake test.. and it works just fine.. I don't understand how it can idle perfectly until it warms up.. then you can literally feel the engine lose power and idle terribly.. The dealership said they ran nearly every test on it they could... and no problems.. no codes.. Days like today where it's 65 degrees.. it feels like it's going to stall.. but doesnt.. days when it's 100 degrees it runs perfect.. surely someone else has this issue!
Fleet Owner
Joined: Mar 2012
Posts: 26,199
Likes: 4,151
From: Near Cal. Avenue
It still sounds like it is a vacuum issue. I have 27,000 miles on my 11 ta 12 3.7L without a miss or anything related to one. Yours is probably in the intake manifold but time will prove out what it is. Keep your head up and with your dealer, even a second opinion is good. This trucks OBDII is incredible. Get a good Scanner that will record in real time and you can graph it when it misses. It won't take you that long to spot the irrgularity of a sender if so. I have put my pids on my album if you want to compare at 60 mph and warmed up. They read left to right each pid on a line.
https://www.ford-trucks.com/forums/m...+pictures.html
https://www.ford-trucks.com/forums/m...+pictures.html
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