1998 Ford windstar - Pulsing and hissing sound on acceleration only.

[1998windstar300K]

Hello to all!!! I am having a problem with my 1998 Ford Windstar 3.8l (300KM) and I have hit a dead end!!! Over the last 2 weeks I have develloped a Pulsing and hissing sound on acceleration ONLY.. No noise in Neutral or idle (slight noise when Rev >2500RPM in neutral). On acceleration the noise sounds like its coming from the drivers side front to middle of van. I had it up on ramps again tonight and I cant isolate where it coming from, checked belts, air intake, exhause manifold (all visual checks).

There is also a slight raw exhaust smell coming from the underside but again I cant isolate it as I work in an uncovered driveway with wind! (maybe when its colder I'll see the vapor?>). One more thing that's throwing me off is there is no change to my acceleration? she still go's but sounds like I'm sitting on top of a broken air compressor!

I searched thru the forums and couldnt find anything!! Anyone got some advise as to what is happening??

[scubacat]

No CEL?

I'd probably smoke test for a vacuum leak to start with.

[tempfixit]

You may want to do a vaccum test and fuel preessure test.

http://www.secondchancegarage.com/public/186.cfm

Info on checking vacuum,

[wiswind]

RAW exhaust smell......I would check the flex joint that is under the vehicle.
It is located just ahead of the huge square muffler that is under the driver's seat.
The "Y" pipe with both catalytic converters moves with the engine.....the flex pipe is between the "Y" pipe and the pipe coming out of the muffler.
It is possible that this could be a source of hissing noise as well.......depending upon the nature of the hole.

Otherwise, I would remove the air filter tube.....and look for any signs of leaves being caught in the air intake from the driver's side fender......
Inspect the flex hose between the air filter / MAF tube and all hoses that connect to it.
Also....inspect the hose from the top of the intake manifold to the PCV valve.......if that is all original, the elbow on the top of the intake manifold and/or the soft hose sections could be cracked or also collapsing under vaccum.
However....I would expect the PCV situation to be worse at idle.....as the vaccum in the intake....that is from the engine side of the throttle plate to the intake valves to the HIGHEST at idle.
However....the draw through the flex tube and air filter will be max under hard acceleration , bringing that part more inline with your symptom.

[1998windstar300K]

Originally Posted by wiswind

RAW exhaust smell......I would check the flex joint that is under the vehicle.
It is located just ahead of the huge square muffler that is under the driver's seat.
The "Y" pipe with both catalytic converters moves with the engine.....the flex pipe is between the "Y" pipe and the pipe coming out of the muffler.
It is possible that this could be a source of hissing noise as well.......depending upon the nature of the hole.

Otherwise, I would remove the air filter tube.....and look for any signs of leaves being caught in the air intake from the driver's side fender......
Inspect the flex hose between the air filter / MAF tube and all hoses that connect to it.
Also....inspect the hose from the top of the intake manifold to the PCV valve.......if that is all original, the elbow on the top of the intake manifold and/or the soft hose sections could be cracked or also collapsing under vaccum.
However....I would expect the PCV situation to be worse at idle.....as the vaccum in the intake....that is from the engine side of the throttle plate to the intake valves to the HIGHEST at idle.
However....the draw through the flex tube and air filter will be max under hard acceleration , bringing that part more inline with your symptom.

WOW... I did a smoke test(Vacuum test) on Thursday last week and all came back good (out 2hrs shop labor but in the end we did find out the source while up on the hoist!

It was the Y Pipe and the associated connectors(smell and hissing) and my CAT on the drivers side is also blown(marbles sound inside). In the end the shop stated it would cost several hundred to fix and that was not including the cost of the CAT and the Exhaust piping!! total $2000 approx.. SOOOOOO I decided not to fix it at this time and went out and purchased a 2007 Kia Rondo EX (my first non FORD in 15 yrs!).. My 1998 Ford Windstar will be driven to the cottage and used a backroads work vehicle!! THANKS ALL FOR THE HELP!!