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HELLO, I JUST BOUGHT A 95 CHRYSLER CIRRUS LXI, AND IT RUNS GREAT, JUST A FEW DAYS AGO IT STARTED REVVING UP ON IT'S OWN, THE RPM'S GO UP PAST 3 ON THE GAUGE, IT GOES UP AND DOWN. THE CARS ALSO TRIES TO STALL OUT, BUT IT HAS NEVER DIED ON ME. IF I TURN THE CAR OFF AND WAIT A FEW SECONDS THEN START IT BACK UP IT RUNS FINE AGAIN. WHEN THE CAR IS ACTING UP IT ALSO FEELS LIKE IT SHIFTS HARD ?, WHEN I STOP SOMETIMES THE CAR TRIES TO JUMP FORWARD ALSO, BUT I FIGURE THIS IS DO TO IT TRYING TO REV UP. ALSO WHEN I AM DRIVING DOWN THE ROAD THE CAR MAKES A WHISTLING SOUND WHEN I LET OFF OF THE GAS THE NOISE STOPS,THEN STARTS AGAIN WHEN I GIVE THE CAR GAS. ANY ANSWERS WOULD REALLY HELP. THANKS SO MUCH..
Answer -
Hi Trish,
Your description was very detailed and helpful. It appears that there is an air hose fitting (vacuum line) that is connected to the intake manifold (which is fed air after it goes thru the air filter) where the engine's operation causes there to be a partial vacuum which varies depending upon whether you have the throttle pressed open by the gas pedal and also with the rpm of the engine at any given moment. This is called a "vacuum leak". Usually it is a plastic hose or rubber hose that is cracked or has come loose from the nipple to which it should be attached. The engine control system interprets the leak as if the mixture of fuel and air is too lean, so it gives it more gas all by itself which why it revs up.
You merely have to find where the leak is. You didn't mention the engine so it is not possible to tell you what to diassemble in order to get in around the intake manifold, but there is a sticker on the underside of the hood that shows all the vacuum hoses and also the intake manifold which creates the vacuum. So once you have a clear vision of all the hoses it is just a matter of inspecting them to look for the leak. Another way is to buy a spray can of starter fluid at an auto parts store and then with the engine at idle put a very tiny squirt of starter fluid at each hose fitting and listen for a change in the idle speed for a moment right after each squirt. Use very little as it is flammable, and you don't need but a tiny burst to cause a perceptible change in the idle speed at the point of a vacuum leak. You might even hear the whistle when it is idling though usually the vacuum is not so great as when you take your foot off the gas when going along a 30-50 mph when it is easier to hear the air suction sound.
So, if you don't feel up to searching for it yourself you now know exactly why you have this problem and you can go to a mechanic that you trust and say "I authorize you to look for a vacuum leak and correct it". That way you limit the amount of time and dollars spent on the repair. Don't accept a big story about some major issue unless it can be shown to you exactly where the leak is and why it is such a big deal. Usually you can find such a leak in a fraction of an hour.
Roland
I ALSO FORGOT TO ADD THAT WHEN THE CAR TRIES TO STALL IT DOES NOT DIE BUT IT WONT MOVE BUT ABOUT 5 MILES PER HOUR, LIKE IT HAS NO FUEL. AND IF I TRY TO GIVE IT GAS IT JUST SPUTTERS. SORRY SO LONG JUST WANTED TO GIVE YOU ALL THE INFO I CAN... THANKS SO MUCH AGAIN AND HAVE A GREAT DAY ! ENGINE IS 2.5 V6...
AnswerHi Trish,
When you have a vacuum leak the engine is alternately going to run rich or lean, rev or stall, so I think it all part of the same issue. I note that my manual for the V-6 shows the intake manifold to be sitting on top of the engine on the side nearest the passenger compartment. It is a very large single casting and my manual also show that there are relatively few vacuum hoses that you would need to locate at the manifold and check out by just following the sticker drawing until you find a disconnected hose or a cracked hose and correct the situation by either reconnecting it, or you might be able to just trim off a cracked piece on an end if there were enough length, or take the hose to a dealer or a good auto parts store and get a replacement. Trace each of the dark lines labelled M or MV along their length and thru and on to the various parts to which they are attached until you have traced and checked all of them. I suspect it it a single hose, so when you find a leak and fix it you can then give the engine a try to see if it is running right, and if not, keep looking for another leak. You will see the letters MV or M on the drawing and if you can locate those points then you are in business. It is also possible if you don't find a cracked hose that you have a loose nut or screw on the throttle body where it attaches to the manifold (see drawing) and there are 7 bolts that hold the upper part of the intake manifold to the lower part and if any of those were loose that too would be a spot for a leak. Also check where the MAP sensor attaches to the manifold to see that it isn't loose. Again refer to the underhood sticker for all these items.
I am quite certain that when you find and fix the leak everything will be corrected.
Roland
