Originally Posted by merriman67
OK!!! Here's something else that may help solve the problem. I got the car to crank today and my brother checked some fuses and plugs but he really doesn't know a lot about vehicles either. When I accelerate the gas while it's in park instead of holding a steady acceleration it revs up and down???? But I'm holding the gas pedal steady?????
what does that sound like to you guys????
Hi- I stumbled upon your thread while looking up info for something going on with another one of my luminas (I own 3 luminas, a 97 & a 99 with 100,000 miles on each, and a 1998 with 236,000 miles -awesome cars if you take good care of them)
My 1998 lumina has the 3.1L (3100) v6, & it acted a lot like yours does when I bought it (up/down idle in park, idle surge when decellerating to a stop, surging/sputtering at cruise once-in-a-while). Some mechanics I knew told me its' idle was bouncing on the rev limiter too, and it probably was, but only because something else was broken, and everybody was stumped, so they sent me on a wild goose chase of filters, additives & all sorts of stuff. But I fixed the problem with one $25 part and an afternoon of diagnostic & installation time, & now the car runs like new.
First, check the engine for Vacuum leaks, (any time your idle goes nuts, start here). I'd look for any cracked vacuum tubes or cracked rubber caps. When I found one with cracks, I'd unplug it if possible & then plug it back in, (do this one end at a time, one tube at a time, and DO NOT unplug rubber tubes/hoses held on with clamps-check those tubes for cracks only) and make sure all the rubber tubes & caps are on tight & snug at both ends (loose fitting vacuum lines are a no-no), and then i would cover over any cracks I see in the rubber with vaseline & listen to the engine run, & see if the idle smoothed out, if it did, I would replace that cracked line or rubber cap.
That process is how I found the source of the crazy over-rev condition you spoke of, (it also explained some other crazy fuel starvation/engine surging issues I had too, & it was all because of this one $25 part)
On the fuel injector rail, (top of engine, toward front of car) tucked under the driver-side, front corner of the intake manifold, near the throttle body, is a small vacuum controlled fuel pressure regulator
. It is a metal, vertical, cylindrical device about 1 1/2 inches tall, shaped like a miniature metal beer keg, with a vacuum line coming out the top end.
There is a vacuum diaphragm inside that device that got a hole in it from old age, and started sucking raw fuel into that vacuum line, and sent raw fuel through the "map sensor" on the back side of the intake manifold (the big flat 6 legged metal piece that says "3100 v6" or "3.1 Liter" or similar embossed across the top), and into the air intake system (obviously where raw fuel isnt supposed to go on a fuel injected car) this caused the car's computer to freak out, & thus, the car to have stumbling, surging, & crazy idle fits similar to what you are describing.
You will find if this is your problem when you remove the vacuum tube from it, and find fuel bubbling out of the metal hose connector.
After I replaced that pressure regulator, this 236,000 mile lumina has been running like a new car, & now my daughter proudly drives it all the time.
It is not easy for a newbie to change this little part, and it will require some specialized hand tools (flare-nut wrenches, etc) to change it, but it is not impossible for an average "Backyard mechanic" to do it. So if you see fuel coming out of that vacuum connection, I recommend you buy a new fuel regulator at your local parts store (make sure the part looks identical to the one on the car!), and then contact a buddy who works on cars for a hobby to change it or you if you are not mechanically inclined.
While you are welcome to call the dealer for a price quote to change this part, I'd suspect your local car dealer will probably charge you a fistfull of cash to do this job, just because it is technically considered part of your fuel injection system, and all the extra tests & stuff they will try to sell you on because you have a car thats over 10 years old. (dealers have lots of bills to pay too)
I hope this will help you-