kaiserkreb Posted May 20, 2008 Report Share Posted May 20, 2008 So every once in a while, when I start up my SGT, I hear a small thump from up around the spot where you hear the sigh of the cold air intake when you shut the car off. Does anyone else ever hear something to this effect? It's ONLY when you start up the car. Is there a flap closing in the CAI when you start the car? I'm fairly ignorant when it comes to mechanics so this is just speculation of course, but if anyone has an inkling I'd love to hear your input. Thanks in advance. Darren Link to comment Share on other sites More sharing options...
68fastback Posted May 20, 2008 Report Share Posted May 20, 2008 Is it possible it's from under the dash -- maybe one of the HVAC 'doors' opening/closing? Does it do it regardless of the air/AC/heat settings? DUnno.. just some thoughts... Dan Link to comment Share on other sites More sharing options...
kaiserkreb Posted May 20, 2008 Author Report Share Posted May 20, 2008 Is it possible it's from under the dash -- maybe one of the HVAC 'doors' opening/closing? Does it do it regardless of the air/AC/heat settings? DUnno.. just some thoughts... Dan never thought of that, though I am almost positive it is coming from up under the drivers side quarter panel area. Link to comment Share on other sites More sharing options...
LuLu Posted May 21, 2008 Report Share Posted May 21, 2008 I'm not making fun of you, I'm trying to help. There are no "flaps" anywhere in the induction system, until air reaches the throttle body blade, which is mechanical. It doesn't move until the engine starts, and it doesn't move after the engine is shut off. So, any "sounds" you may hear before the engine starts, or, after you shut it off, are coming from somewhere else. HVAC doors are a good place to start, however, you mention "quarter panel" as a source, and this is a hint. Sitting in the front drive/passenger seat, the quarter panel is over your shoulder, behind you. If this is where the sound seems to come from, it's another hint. The sound you hear at ignition on-off may be the fuel pumps. There are two of them, and they reside underneath your rear seat cushion. They are electric, which means they come on and turn off with the ignition key. You don't have to start the engine to stimulate them. I can't say I'm right, but tracking down "sounds" is difficult over the Internet. Hope this helps... Link to comment Share on other sites More sharing options...
pottydr Posted May 21, 2008 Report Share Posted May 21, 2008 If its a automatic, and do you hear it when you put your foot on the brakes, it may be the switch to release the car outta park, thats my guess Link to comment Share on other sites More sharing options...
motorjock205 Posted May 21, 2008 Report Share Posted May 21, 2008 HID lights make a thump sometimes when you hit the switch...I had trouble figuring out what the thump was when I would go from low beam to high beam and back until I had my wife cycle it and saw the HID cover moving...DOH! Link to comment Share on other sites More sharing options...
kaiserkreb Posted May 21, 2008 Author Report Share Posted May 21, 2008 I'm not making fun of you, I'm trying to help. There are no "flaps" anywhere in the induction system, until air reaches the throttle body blade, which is mechanical. It doesn't move until the engine starts, and it doesn't move after the engine is shut off. So, any "sounds" you may hear before the engine starts, or, after you shut it off, are coming from somewhere else. HVAC doors are a good place to start, however, you mention "quarter panel" as a source, and this is a hint. Sitting in the front drive/passenger seat, the quarter panel is over your shoulder, behind you. If this is where the sound seems to come from, it's another hint. The sound you hear at ignition on-off may be the fuel pumps. There are two of them, and they reside underneath your rear seat cushion. They are electric, which means they come on and turn off with the ignition key. You don't have to start the engine to stimulate them. I can't say I'm right, but tracking down "sounds" is difficult over the Internet. Hope this helps... I realize that, and I appreciate any help you guys have. I guess maybe my car lingo isn't up to par but I meant the front quarter right around where the CAI sits. I'm pretty sure the sound is coming from in front of me, almost as if it's the suspension or something settling, but it has only ever happened so far after the car has been started and running for maybe 5 seconds. I also don't have HIDs so I'll have to rule that out by default. =) Thanks for the replies though everyone, I'll keep on looking and definitely check into the HVAC doors. It seems a little too loud for those I would think but it's worth a look. Darren *edit* not an auto either, I'd get too bored if I wasn't shifting all the time. Link to comment Share on other sites More sharing options...
khogle2 Posted May 21, 2008 Report Share Posted May 21, 2008 I realize that, and I appreciate any help you guys have. I guess maybe my car lingo isn't up to par but I meant the front quarter right around where the CAI sits. I'm pretty sure the sound is coming from in front of me, almost as if it's the suspension or something settling, but it has only ever happened so far after the car has been started and running for maybe 5 seconds. I also don't have HIDs so I'll have to rule that out by default. =) Thanks for the replies though everyone, I'll keep on looking and definitely check into the HVAC doors. It seems a little too loud for those I would think but it's worth a look. Darren *edit* not an auto either, I'd get too bored if I wasn't shifting all the time. i can tell you with other brands, two things are somewhat common: 1. a/c freon slug when starting under certain conditions. the a/c compressor does not engage until after the idle stabilizes on start up after a second or two, sometimes causing a big clunk noise from the freon pressure. this shows up on every brand one time or another, the phantom clunk. sometimes this happens only once every couple of weeks or months. only when the compressor engages, so not under whatever the threshold is for temp. (not in a canadian winter) 2. certain models are prone to heater core clunk, like a hydraulic clunk from water pressure, certain models have a restrictor in the feed line to the heater core as a service fix. not talking about fords necessarily in either of these scenarios. also neither would be in the left front of the car, so I might not be even remotely close to the cause. shut off the hvac control (not just on low, but off) and try a couple of starts in whatever conditions set up the noise remember, the a/c compressor cycles on in defrost mode to, even if you dont engage the little a/c switch) . Link to comment Share on other sites More sharing options...
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