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MAF dampener

 
Old 12-07-2018, 02:06 PM
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vanster
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Default MAF dampener

Why is it that on the PET diagram shows vacumm lines and the one on my 81 is plugged? 5sp vs Roger box?
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Old 12-07-2018, 02:18 PM
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Someone skipped a step in the past..
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Old 12-07-2018, 03:56 PM
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What would be the reason?
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Old 12-07-2018, 04:14 PM
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Why would anyone want to wet their MAF?
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Old 12-07-2018, 06:45 PM
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Originally Posted by vanster View Post
What would be the reason?
Not familiar with the use case for that part..
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Old 12-07-2018, 11:54 PM
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Thats the decel valve.

allows air to bypass the throttle plate on decel, so the engine doesnt stall.

you dont have a MAF in that car
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Old 12-08-2018, 12:01 AM
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That is the vacuum limiter introduced in 1983 so perhaps your throttle body was switched out for a later unit and this was capped off?
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Old 12-08-2018, 05:16 AM
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Funny that Porsche says the autos don't need it. When mine went bad my 81's engine rpms would rise and fall while coasting in a cyclical fashion. It was odd.

I would have it hooked up personally but many run without it with no problem.
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Old 12-08-2018, 10:43 PM
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it was not introduced in 83. My 81 has it. I think its on any K jet or L-jet engine.
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Old 12-09-2018, 09:07 AM
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Originally Posted by granprixweiss928 View Post
it was not introduced in 83. My 81 has it. I think its on any K jet or L-jet engine.
You are correct, looking further it goes all the way back to '78
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Old 12-09-2018, 12:33 PM
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Originally Posted by vanster View Post
What would be the reason?
Removing this device allows the engine speed to plummet very rapidly when not under load. This is bad for emissions and can also cause the engine to stall out. I suspect if you free rev your engine and take your foot off the gas, the RPM's fall to below idle and "bounce" back up. That's typical when these are bypassed.
The idle switch is often disconnected with this "mod" too, which allows raw fuel to be dumped into the exhaust giving you that "snap-crackle-pop" sound on deceleration.

I ran my 81 like this for a while and put it back on. Frankly it's annoying since randomly the engine can stall if they fall too fast and the computer doesn't catch it. It also made the car more difficult for my wife to drive since the engine speed would fall so fast between shifts it made for abrupt driving.

Modern cars control this via the ECU.
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Old 12-09-2018, 12:43 PM
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The consensous is to plumb it as per the PET . Toss the nipple. This could be one of the reasons I had such a difficult time trying to keep the car running.
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