Low idle/engine shuts off while driving

OFXAOS

MEMBER
2003 JEEP LIBERTY
3.7L
V6
2WD
AUTOMATIC
190,992 MILES

When I first start the vehicle up it seems fine. However just recently I noticed my idle is below 1,000 (500 to be exactly) I think nothing of it and start pulling out my drive way when it shuts off. I wasn't pressing the gas nor the brake. I put it back in park turn it on and go and as long as I'm giving it has the truck goes with no problems. It is when I lift my foot off the gas the idle needle drops below 1,000 real quick and on a few occasions has turned the vehicle off on me. I lose power steering, braking is difficult. At one point in time I had to regain control quick and ended up throwing it in neutral then drive. Probably not the best thing for my super old automatic transmission. The engine has been replaced around the 137,000 range on the body. The replacement engine had 43,000. This was over four years ago. Since having the new engine I have replaced the alternator, the thermostat, water pump, spark plugs, radiator cooling fan, fan relay, radiator its self along with the upstream and down stream hoses. Replaced the front and rear rotors along with brake pads, which really none of that has to do with the problem at hand. I'm not sure if it's an idle control sensor, maybe I need a new battery * note worthy this truck has had a 1600.1 mono Class A/B Boss amp pushing a single Pioneer 10 sub-woofer. Also I have an aftermarket DVD player as well plus my four door speakers have been replaced by pioneer 6.5's (yes I removed those crazy "stock amps" the speakers are powered by the head unit. It wasn't until I tried upgrading to a Boss 2000.1 Class A/B pushing two 12in MTX Terminator subs that this problem started.) I since have disconnected all power sources and removed the Rica's and remote wire. Unhooked the power wire from the battery. Only thing that throws me off is I had a fuse on this power wire to keep it from draining the battery. So I'm not sure if its my battery or my crappy 136 amp alternator. Has anyone had any experience with super low idle and then the engine along with power steering, power brakes, etc. Just shutting off? I wouldn't even know if it was off if my power steering didn't give out. The A/C still blows and the radio still plays. It's dangerous to drive really.

1 Reply

CARADIODOC

MECHANIC
33,858 POSTS

The loss of power steering is a common symptom, but be aware you will never lose total control of steering or brakes when the engine stalls.

Chances are this problem started right after the battery was disconnected for some other service. The Engine Computer needs to see a very specific set of conditions for it to relearn "minimum throttle". Until that is done, the idle speed will be too low, as you've observed. To meet the conditions for the relearn to take place, drive at highway speed with the engine warmed up, then coast for at least seven seconds without touching the pedals.

Don't be too hard on your alternator. Chrysler invented them and first used them on 1960 models, and they copyrighted the term "alternator". They originally had the world's best design for many years. Today they use Nippendenso generators that are still easy to diagnose and repair, and they are much easier to work on than any other brand.