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Registered
Join Date: Jul 2001
Location: Arizona
Posts: 230
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Mass Air Sensor Noises
I have a 93 that the PO put an autothority Mass Flow Sensor kit on, and I didn't get the original trap door with the car. As the throttle is cracked under load I am getting a whistle that modulates with the engine load and throttle angle. At first I thought it was just the nature of the beast, but this is so loud I have a hard time believing that it is normal. I've looked around for a vacume leak, tightened every band I could get a wrench on to no avail. Because it only occures under load I have no way of listening for it in the driveway. (I'm trying to find a way to bungee cord myself to the rear deck at this point and have a buddy drive me around the block...) Any Ideas? I've pestered a few guys that have the same setup with mixed results...
------------------ 93RS |
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08-02-2001, 09:55 PM
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Join Date: Jan 2001
Posts: 696
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I think that setup uses a K&N filter, if it does what you are hearing is comming from the the intake (air rushing around the throttle plate). I experienced the same sound after removing the airbox and installing a K&N filter with adapter on my '87. Apparently, the factory airbox normally muffels this sound.
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08-03-2001, 09:09 AM
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Join Date: Jul 2001
Location: Arizona
Posts: 230
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Thats what I orignially thought, although when I called autothority they said it was probably a dirty filter! I've cleaned & reoiled with no change, so I guess I will have to live with it. It does sound good when you whomp on the throttle though...
------------------ 93RS |
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08-03-2001, 10:18 PM
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I have a '90 C4 and was thinking of using Virgina's Authoauthorty to put in their Mass Air Sensor in order to perhaps cure my hunting idle problem. Would you recommend them after your current experience ? They are suppossed to be great 911 tuners, dyna and all.
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08-04-2001, 05:30 PM
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Registered
Join Date: Jul 2001
Location: Arizona
Posts: 230
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Well, I purchased the car with the autothority mass air flow sensor, and one of their chips, adjustable fuel regulator, cat bypass and B&B final muffler. It also has the lightweight clutch.
In order to pass the local emissions I had to have the cat put back on. I didn't notice any appreciable difference in the performance of the car, but it still would not pass. My mechanic was convinced that the Motronic was dumping in too much fuel at idle/low rpm. I ordered a modified chip to handle emissions (sent autothority a copy of the test) and up the rpm to help with the lightweight clutch (tends to stall) I got a new chip, did not perform as well and it was too lean this time. Went back for a third (no charge) and finally got it to pass. I put the original chip back in for performance. The idle still hunts and you have to let it stabilize after a hot start or it will stall. Coincidentally while I had my car in, my shop was in the process of removing the same setup from a 94 roadster and reinstalling the factory gear. You may have better luck having your car in their shop, it's hard to do 2,200 miles away by phone & fax. I would seriously see if they had a car you could drive prior to getting this upgrade. If you are like me the intake squeal is not acceptable.(and I had a 67S with webbers and stack filters). Despite the added gain I would prefer the stock setup. I do think that the exhaust upgrade and just the chip may be your best bet (it worked wonders on my 84), and I've seen a lot of 964 airboxes drilled out to get more air. If you find out you want this setup, let me know, I might have a trade for you... ------------------ 93RS |
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08-05-2001, 07:21 PM
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