1997 mountainier starting trouble

[stehle_kim]

I have a 1997 Mercury Mountainier. The gas goes so fast I can't take my foot off the brake and then when I shut off the car, it won't start again. Sometimes when I have stopped for a traffic light, when I push the gas to go again, it stalls and then won't start again until it is cold. I have replaced 4 different sensors. The 02 sensor and the fuel pressure regulator also. I can't drive the car because if I turn the motor off to go into a store, it will not start again until it has set for a couple of hours too get cold.

[Davescort97]

Sounds like the engine has a vacuum leak either off the intake plenum or somewhere in the PCV valve system. Check for loose or cracked vacuum hoses. Check the Idle Air Control valve. If it is really hard to push down the brake pedal to stop the diaphragm or the hose on the brake booster is leaking.

[stehle_kim]

Originally Posted by davescort97

sounds like the engine has a vacuum leak either off the intake plenum or somewhere in the pcv valve system. Check for loose or cracked vacuum hoses. Check the idle air control valve. If it is really hard to push down the brake pedal to stop the diaphragm or the hose on the brake booster is leaking.

hi dave, in addition to the parts we first mentioned we have also replaced the following, egr valve and egr positioning sensor. When my wife said she had to push the brake pedal so hard to get the car to stop, she was meaning that in the sense bacause the engins was running fast it took more pressure, not that the pedal itself was unusualy hard to push. Also i'm of the opinion that if we have a vaccum leake wont the engine run rough? It runs good and smooth. Another thing i discovered the other day i was using some spray cleaner to clean the mass air flow sensor. I'm not sure what the piece is called but it mounts on top of the butterfly and is hooked up with two wires. It looks like when it is energised it by passes the butterply and lets air in . Any way when it is unpluged the engine idles down and when you plug it in the engines revs up like 12 to 15 hundred rpm's. Thanks dave cant wait to hear from you.

[shorod]

The Idle Air Control (IAC) is mounted to the throttle body and does exactly what you describe, it allows air to bypass the throttle plate to maintain the correct idle speed. They have been known to fail, but it sounds like yours works and maybe it's getting a signal to open further than it should. You don't by chance have the defroster on but the A/C compressor unplugged, do you? The IAC is also used to increase bypass air to account for various loads such as the A/C compressor and the power steering, as well as fast idle when the engine is cold.

-Rod

[stehle_kim]

Originally Posted by shorod

The Idle Air Control (IAC) is mounted to the throttle body and does exactly what you describe, it allows air to bypass the throttle plate to maintain the correct idle speed. They have been known to fail, but it sounds like yours works and maybe it's getting a signal to open further than it should. You don't by chance have the defroster on but the A/C compressor unplugged, do you? The IAC is also used to increase bypass air to account for various loads such as the A/C compressor and the power steering, as well as fast idle when the engine is cold.

-Rod

hi rod thanks for getting back, no the ac is not unplugged. we have replaced the egr valve, the vmv valve, replaced o2 sensor, and ban 2 sensor 1 02, and cleared codes. that didn't fix the problem so i replaced the fuel pressure regulator, and cleaned the throttle body and IAC. THE CAR WILL START RIGHT UP IN THE MORNING LIKE NORMAL, AFTER IT WARMS UP THE ENGINE RPMS COME UP AND IF YOU SHUT IT OFF IT WILL NOT START AGAIN UNTILL IT HAS SAT FOR A LONG TIME. I HAVE ONLY GOT IT TO RESTART A COUPLE OF TIMES WITH A LOT OF CRANKING AND IT SMELLS LIKE GAS WHEN IT DOES. I HOPE THIS GIVES YOU MORE TO GO ON. SURE NEED HELP. THANK YOU FOR YOUR PREVIOUS RESPONCE AND WILL WAIT TO HEAR BACK.

[shorod]

If you have access to a fuel pressure gauge I'd be very curious to see what happens if you install the gauge at the fuel rail, then check the pressure KOEO, KOER, and then see how quickly the pressure drops when you shut the engine off. Also check for evidence that someone may have tampered with the throttle plate stop screw. You can check this by removing the air intake tubing from the throttle body and confirming that the throttle plate is completely closed when there is no pressure on the accelerator pedal.

-Rod