Removing Deceleration Valve?
06-11-2009, 10:04 PM
#1
Three Wheelin'
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Removing Deceleration Valve?
I know many don't even work, and some folks have taken them off. My new TB has no provisions for one. What issues might I experience with out one? 
06-11-2009, 11:48 PM
#3
Nordschleife Master
The purpose of the decelleration valve is to let air in when the throttle closes suddenly. The engine runs too rich otherwise as the FI system is a bit less responsive.
I plugged the vacuum line to mine and credit that, in part, to some wicked cool flame-throwing exhaust system backfires it produces during quick shifts from WOT. If ya like that, go for it.
I plugged the vacuum line to mine and credit that, in part, to some wicked cool flame-throwing exhaust system backfires it produces during quick shifts from WOT. If ya like that, go for it.
06-12-2009, 12:49 AM
#5
Man of many SIGs
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I removed the one on my turbo car the last time I had it apart. So far I haven't noticed any difference. Theres a good thread somewhere about it that was started by Porken. I would find it for you if the new search wasn't such a PITA.
06-12-2009, 12:54 AM
#6
Administrator - "Tyson"
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I put mine back on, the revs fall so fast between shifts it made the car a real PIA for my wife to drive.
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06-12-2009, 01:14 AM
#8
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It's very simple:
1. Run the car up to redline in any gear - WOT for full effect
2. Push in the clutch / lift off the gas as if you are going to change gears...do nothing else.
3. If the revs "hang" for a second or two, then slowly drop down to idle, it's working.
If it falls like a rock, it's not working or not installed.
If you are going to remove the valve you should also disconnect the idle switch. When this switch is activated, fuel is cut off to prevent unnecessary fuel from getting dumped into the exhaust. Problem is, the revs fall so fast the car falls well below idle, then bounces back up when the fuel comes back on.
06-12-2009, 01:40 AM
#10
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I doubt it since the injectors are not electronically controlled?
06-12-2009, 01:43 AM
#11
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1-2 seconds? "one one thousand, two one thousand" , like this??
Like I said, and from someone that took my engine to redline more than anyone, it wasnt a noticeable differnce. the idle switch on decel is good to remove for a coupe of reasons, but primarly, its for not allowing the idle to fall below and possbly stall in racing conditions. rpm comes down from redline near the same, just with the small amount of fuel in there, it causes some poping on decel.
Not a big deal. euros didnt have them , but had idle switches.
dont worry about it. Its not a big deal. PLus, you dont have it.
Hey, I didnt know what the heck it did, so i had my euro throttle body modified to accept the vacuum system to be identical to the USjet. in the end, it wasnt really needed when i found out what it did. by the way, with it, the engine still could stall racing, if the idle switch was working. when, disconnected, all was good.
mk
Like I said, and from someone that took my engine to redline more than anyone, it wasnt a noticeable differnce. the idle switch on decel is good to remove for a coupe of reasons, but primarly, its for not allowing the idle to fall below and possbly stall in racing conditions. rpm comes down from redline near the same, just with the small amount of fuel in there, it causes some poping on decel.
Not a big deal. euros didnt have them , but had idle switches.
dont worry about it. Its not a big deal. PLus, you dont have it.
Hey, I didnt know what the heck it did, so i had my euro throttle body modified to accept the vacuum system to be identical to the USjet. in the end, it wasnt really needed when i found out what it did. by the way, with it, the engine still could stall racing, if the idle switch was working. when, disconnected, all was good.
mk
Then it was broken.
It's very simple:
1. Run the car up to redline in any gear - WOT for full effect
2. Push in the clutch / lift off the gas as if you are going to change gears...do nothing else.
3. If the revs "hang" for a second or two, then slowly drop down to idle, it's working.
If it falls like a rock, it's not working or not installed.
If you are going to remove the valve you should also disconnect the idle switch. When this switch is activated, fuel is cut off to prevent unnecessary fuel from getting dumped into the exhaust. Problem is, the revs fall so fast the car falls well below idle, then bounces back up when the fuel comes back on.
It's very simple:
1. Run the car up to redline in any gear - WOT for full effect
2. Push in the clutch / lift off the gas as if you are going to change gears...do nothing else.
3. If the revs "hang" for a second or two, then slowly drop down to idle, it's working.
If it falls like a rock, it's not working or not installed.
If you are going to remove the valve you should also disconnect the idle switch. When this switch is activated, fuel is cut off to prevent unnecessary fuel from getting dumped into the exhaust. Problem is, the revs fall so fast the car falls well below idle, then bounces back up when the fuel comes back on.
06-12-2009, 01:43 AM
#12
Three Wheelin'
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Just making sure I wasn't missing something. WUR should control fuel at idle based on vacuum. I have the unwiredtools WUR ready to go on once the engine is sorted and running well. Don't want to try to map out the fuel until I know everything else is kosher.
