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Discussion Starter #1
got a problem to diagnose

1997 Mercury Grand Marquis 4.6l v8
108,000 miles

Sometimes (becoming more frequent) I hear a woooooooo sound. Like a fan or a pump maybe. Usually after I have been at slower speed (under 45 maybe) and then am coming to a stop, and then the car just dies. I mean there isn't a sputter or cough or anything, it just quits. It'll start right back up... maybe a little bit more cranking than usual but not much at all. I can stop it from happening if I hear it in time and can either throw it up into neutral (take the load off) or blip the throttle a time or two.

Happens with hot or cold weather.
Happens with hot or cold engine.
Doesn't matter if it is wet or dry.
No codes or lights.


The only thing I can think of might be the fuel pump.


Ideas????
 

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Beware of the dog!
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A girlfriend years ago had a 90-ish Mustang that would occasionally just stall at idle when stopped at a light or stop sign. No codes, many trips to the dealer, they couldn't fix it, basically they didn't try because they had no codes to lead them. I kept telling them the injectors were probably dirty because it acted like a car with a dirty carburetor. I was unfamiliar with fuel injection back then.
Eventually I poured in a bottle of injector cleaner. She never had the problem again.

Whatever it is, good luck.
 

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"TURGID FLUX"
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2001 Ford Expedition 4.6L V8 91 K miles. I took it to the mechanic to have an oil change and a tire leak fixed. When I went to pick it up they could not start it. Never had a problem before. They changed the pump and fuel filter. Not cheap. The fuel sender is part of the pump assembly. I then started to have fuel starvation problems before the low fuel light came on. Back to the garage for a new pump/sender. There appears to be 4 gallons reserve when the light comes on now.

The "woooo" sound is nothing I have heard, now would expect. Is your tank steel or plastic? Mine is plastic so sound like that might not be transmitted. Is the problem happening when tank is low?

I would worry about the evaporative emission control system (EVAP). The carbon canister might be clogged and you are getting a vacuum in the tank. On mine I am smelling fuel vapor when I shut off the engine, back near where the canister is mounted. There are two solenoid valves that can fail.
 
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A plugged evap canister can cause stalling like you describe.
When the RPMs drop, the back pull of the emissions vaccuum (like a sponge after you quit squeezing) can cavitate the manifold momentarily causing the car to sputter or die. If the evap canister is clear, this vacuum doesn't happen.
 

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"TURGID FLUX"
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I think cannon fodder is right on target.

Another thing to check on older cars is for broken rubber hoses under the hood. As the engine moves on the mounts, the cracks can open up and disturb operations.

I had a Ford Probe that would stall out when reversing or over slow speed bumps. The large corrugated hose from the throttle body to the MAF sensor had a hidden crack that would let unmetered air into the throttle body and the engine would lean out. Duct tape was an immediate temporary fix for the $50 part.

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I had a 97 couldn't kill it . Sold it to me son for dirt cheap and he proceded to enhance it with maurader parts and a chip...what awake up it had . He got tired of it around 180,000

I'M THINKING you egr has some carbon build up ..had it happen to a 86 vic.
A cheap try would be to pour slowely a 1/2 of can of sea foam into the brake boost line as well as the other half in the gas tank .
Run it with some rpms in the driveway while pouring into the line and let it stall out.
Wait an hour then fire it up and rev it good . white smoke clould will happen and thats normal
black specks clould means your blowing the carbon out of it.
If that don't work remove egr and clean the carbon out...
There is an actuator attached that can wear out that i recall.

As far as the fuel filter you should be on your 3rd one by now unless you like to replace epensive fuel pumps. filters are cheap insurance and you can DIY with special tools rented for free with deposit at advanced or autozone.
Hope your on your second set of plugs and wires also.
Great cars and with basic maintenence will go 200,000 minimum ..more like 3 or 4 if your not in the rust belt.
I have some short term memory problems lately (that I hope to God it goes away)so I'm sure I missed a few other options....but try these first
 

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Agree with everything above. That is nice mileage for that year. Does the wooo happen while braking or just when you let off the accelerator?
 

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Si vis pacem, para bellum
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I had a 1991 F150 that did something similar. Ended up being the AC compressor was bad causing the engine to die. Seems the compressor was difficult to turn when the AC compressor engaged. Didn't make sense since I wasn't running the AC at the time. Turns out Ford designed the truck to cycle the AC compressor when the defrost was on to ensure the compressor was cycled during the off seasons. Took a while to figure it out. Just a thought.
 

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Paleoconservative
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Could be faulty power brake booster diaphragm that, when brake is applied, a large vacuum leak is introduced, causing engine to stall.

The stall occurs because un-metered (unaccounted for) air is being introduced into the engine's intake tract thru the vacuum line TO the intake manifold coming FROM the now internally leaking, faulty brake booster. Since this unmetered air did not come in thru the air flow meter at the air filter, the engine computer is unaware of it, did not factor it into its fuel calculations, and thus an insufficient amount of fuel was passed thru injectors causing engine to quit.

The reason there is no check engine light or code is because, again, the computer is unaware of mechanical failures like a large vacuum leak, broken valvespring, or blown intake or headgaskets. Its not a malfunctioning sensor that the computer could detect as giving erroneous voltage signals or no signal at all, and then set off a code.

All of this is assuming the vehicle is using conventional brake booster, not hydro boost type, cant remember what years Ford started introducing hydro boost on certain platforms.
 

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Goat Roper
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Well, the EVAP/EGR system "should" cause a code if its in those. The fact that you can work pedal in neutral and keep it running is telling. Can you keep it going WITHOUT shifting in neutral? Could be a torque-convertor lockup solenoid in tranny, which might explain noise. But that system also is computer controlled, but if the solenoid is just "Sticking" and not open, ...
Also, a dirty intake/IAC system would keep it from idling. But, it is a crapshoot cause the problem could be any number of things. The fact that it isnt setting a code makes it more difficult to find. I would try turning ALL accessories off (AC/heat, lights,) ... Noise may or may not be related. You will be chasing your tail if you assume they are the same issue.
 

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My guess is "WOOOO" noise is rad fans on at slow speed, pulling hard on alternator, engine stalls instead of idling due to this increased load because your idle valve is bad/sticking..

Only read Op..

Does your AC being on also make it stall when you come to a stop or idle too low? Does it help possibly?
Your engine drop RPMs when you turn on more electronics?
 

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Wile E Coyote, Genius.
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First thing I would do is get a code reader and check for codes. They won't all light the check engine light.

There used to be lots of vaccuum devices on cars, but maybe less these days.
Transmission vaccuum modulator was one.

Bearing growl on an alternator or water pump can make noise, or A/C clutch .

Get a long screwdriver, hold the handle to your ear and press the tip onto things you think might be making the noise while the engine idles.

Would check for vacuum hose leaks or intake manifold gasket leak.

Not sure on that year, but you might be able to monitor engine vacuum while driving with then code reader?
 

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Wile E Coyote, Genius.
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Idle control valve?
Never even heard of one before.
https://www.mercuryforum.com/forum/grand-marquis-14/engine-stall-280/

https://www.partsgeek.com/mmparts/idle_control_valve/mercury/grand_marquis.html

"An inexpensive part playing a huge role, the Grand Marquis Mercury idle control valve works allows the vehicle to idle without stalling. Essential to vehicle operation, the Grand Marquis Mercury idle control valve is situated at, or beside, the intake throttle body. The engine needs a continuous supply of air for combustion. As the driver steps of the gas, the idle control valve takes lets in enough air for the engine to continue operating.

Shaped like a bullet point, the Grand Marquis Mercury idle control valve forces air through a throttle body control plate shaft opening. The part can be damaged in any number of ways. It also has an estimated lifespan of around 70,000 miles."

https://www.partsgeek.com/catalog/2000/mercury/grand_marquis/fuel_injection/idle_control_valve.html
 

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Another thing about the 97 is they like clean tranny fluid , you can hear the solonoids buzzing when they are dirty don't let it get that far.
There is a J-mod that was developed by one of fords trany enginears for hotrod apps.
It will bark the tires on the 1-2 shift and the tranny holds up well with this. I told him you'll destry the u joints ect ..
nothing ever broke with 70k of use.
Jeez my son kills me, nothing he has is stock!
 

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"TURGID FLUX"
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Well; now that we have collectively determined "that it could be anything", the OP is obligated to report back to us what it was and how much to fix.

My money is it being a simple cheap repair if the OP does it, a very expensive repair (different part) if the dealer "fixes" it.
 

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Wile E Coyote, Genius.
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We already solved it I think. Just needs a new Moose Call. :)

Would be nice to hear back if that was it or not.
 

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I'm not specifically familiar with Fords but it seems like an ICV problem to me..

If Fords are known for ICV "moose calls" then this problem is probably nailed..
 

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"TURGID FLUX"
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Thus ends another valuable episode of Click and Clack, the Tappet Brothers.

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