I'm hoping somebody can help me out. Sometimes when the outside temperature is below 35 degrees, when I come to a stop in my '98 with 4.6, 5 speed, a wierd noise (sounds like an air compressor) comes from the engine and RPM goes to 1500-2000 range. I rev the engine and it goes away. The colder it is outside (doesn't matter how hot/cold the engine is) the more frequently this happens. It does not matter if the heater switch is off or on any setting (defrost, vent, etc.). Ford garage can't diagnose it because of course it never happens for them. This is pretty embarassing when I stop at a stop light and it lets out this noise. Any ideas are greatly appreciated!

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hytek1dr@yahoo.com
http://www.geocities.com/MotorCity/Freeway/7515/

 

Fordman,
Its sounds like the air compressor is kicking in. Is the **** on the dashboard turned to the right side?? I know on my F-250, if I turn the **** to any of the right side selections, the air compressor will kick on and change the rpms in the engine. Try leaving the switch at the off position or turning it to the fresh air side and see if that changes anything. Bugman.

 

You did not post a signature so I ask "Have you made any modifications?"
The Air Aid FIPK made a strange noise until the plastic muffler was replaced.

Have you considered leaving it with the dealer and letting them start it when it is cold so they can hear what you hear?

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97 F-150, 2WD, Reg Cab,Flareside,Dk Toreador Red, Windsor 4.6, Magnecor 8.5mm wires, Bosch Plat +4s, 3.55 LS, EGR Bug Deflector, ******* Bed Cover, Bed Liner, XL Full Length Running Boards, Air Aid Kit, Gibson Single Out Cat Back, Superchips, TransGo Shift Kit, Hellwig Rear Sway Bar, Hellwig 2500# Overload Springs

 

Bugman - it doesn't matter where the heater **** is turned to, off, left, right. Even when the noise and RPM change occurs, I have played with the **** and nothing stops it until I rev the engine. When I'm running around with the AC on or vent or defrost, it sometimes happens and sometimes doesn't.

If you look at my web site you can see modifications I have made. I don't think this started after a peticular change...

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hytek1dr@yahoo.com
http://www.geocities.com/MotorCity/Freeway/7515/

 

I remember a recall for placement of a foam insert to prevent freeze up and sticking of the trottle body in cold weather but I think it was only in 97's. Don't know but the cold weather thing you mentioned got me thinking of that.

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2000 F-250 Super Duty, SuperCab XLT, Oxford white with medium grey cloth captains chairs, 5.4L Triton V8 (260 HP version!), 4R100 4 Speed Automatic Transmission, 4 wheel ABS, Deluxe Aluminum Wheels, Trailer Towing Package, Class IV Hitch, Reece load distribution system, Escort Sensor II Electronic Brake controller, K&N filter, Sure Stop towing skirt, "Westin" black powder coated step bars, "White-White" head lamps, Herculiner bed liner.

 

I had a metallic sounding noise at start-up when it was very cold out. They found it to be a faulty power steering fluid pump. Hope this helps.

 

Fordman, Does this thing sound like a foghorn of sorts. I had the same scenerio happening on my truck after the Supercharger was put on. It turned out to be the IAC or Valve Assembly THRO. Not sure of the name but here is the part number. #f65z-9f715-ea

Hope that helps.

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Mumbly also known as Buck
Carrollton Texas (DFW), Part of the F150 Online Texas Chapter
Black 1999 Stage 3 Roush F-150 Super Cab Flareside
Here are all the goodies: Kenne Bell Supercharger, Roush Suspension, 18"x 9.5 Chrome Wheels, B. F. Goodrich Z295/45, Full Ground Effects, Roush Leather Signatured Interior (Front and Back), Flowmaster with Side Exit Infront of the Wheel, Embroidered Floor Mats, F1 Cobra Hood, ******* Hard Tonneau, Bedrug, Slide Window, and lots of other little odds and ends

Work rhigh@nortelnetworks.com
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[This message has been edited by Mumbly (edited 03-28-2000).]

 

Thanks for the help everybody...

Mumbly, yes, it does kind of sound like a foghorn. I'm getting my supercharger put on April 10 and figured I really should have this fixed before then... Can you expand on what that part is? Valve assembly doesn't sound good and I have to fight Ford everytime I try to get something under warranty.

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hytek1dr@yahoo.com
http://www.geocities.com/MotorCity/Freeway/7515/

 

Glad I could help. Heck glad I had time to look at all the areas lately, otherwise I might have missed this thread. Let me know if that is the fix. Mudder is having the same thing on his truck I think..

 

The guys that put my supercharger call it a IAC, but are not sure of the exact name. The part number is the best way to track it down. I'm not sure where to find it on your truck since Mine has this supercharger the part is in a very easy place to spot now. I would check with the parts department and find out the correct name and go from there. I hope that this is the same thing. Mainly he said that the air was reverberating in this part and making this noice under Vacum.

 

Mumbly is a genius! I went to the Ford garage last night and gave them the part number. It's an "Idle Air Control Valve". Then I went to service and told them what you said and that the last couple times it was there, the techs wouldn't/couldn't do anything about it. The service manager said to bring it in Monday and with that info, they could probably fix it. YES!!!

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hytek1dr@yahoo.com
http://www.geocities.com/MotorCity/Freeway/7515/