# How important is a o2 sensor??



## TWIZTD R32 (Feb 21, 2009)

I have a 83 GTI I purchest about 2 months ago, the PO did some stuff to it, GLI radeator, larger TB, g-grind cam, shaved head, removed the Evap. But he put the mk2 exhaust Mani with the old TT down pipe and no o2 sensor, no cat. 
So the car is running with no o2 sensor and I'm wondering if thats something I should get put in asap or is it not really needed?
Thank you
Shawn


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## turbinepowered (Mar 19, 2007)

You'd get a fairly significant mileage boost if you put one back in... though with all that other stuff, maybe not.
My Fox jumped 5mpg with just the O2 sensor replaced.
The car will run better under partial loads in closed loop.


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## ultravw (Oct 27, 2009)

*Re: How important is a o2 sensor?? (TWIZTD R32)*

I bought one of my 83 GTI's with the same basic mods except for 10:1 pistons and a larger intake tube. The O2 sensor worked fine and gave me around 28 mpg with the 1.8 16V trans. Make sure the full throttle switch is properly installed and functioning and the sensor should not hurt the performance any but help with emmisions and fuel economy.


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## TWIZTD R32 (Feb 21, 2009)

*Re: How important is a o2 sensor?? (ultravw)*

Thanks!









_Quote, originally posted by *ultravw* »_I bought one of my 83 GTI's with the same basic mods except for 10:1 pistons and a larger intake tube. The O2 sensor worked fine and gave me around 28 mpg with the 1.8 16V trans. Make sure the full throttle switch is properly installed and functioning and the sensor should not hurt the performance any but help with emmisions and fuel economy. 

How can I check the full throttle switch?


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## ultravw (Oct 27, 2009)

*Re: How important is a o2 sensor?? (TWIZTD R32)*

You can check the switch by using an ohmmeter, but best off to test the electrical system. With the engine warm you can hold on to the O2 sensor terminal and then touch the negative battery terminal and wait to see if the buzzing changes at the frequency valve, which will affect the engine's running. Repeat the test with the positive terminal and it will cause a change back to normal then to running ruff. During these tests you can press on the switch and should get the same buzzing pitch every time.


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## MFZERO (Mar 13, 2002)

*FV-QR*

my 4000 currently runs like crap without an O2 sensor.


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## TWIZTD R32 (Feb 21, 2009)

*Re: FV-QR (MFZERO)*

Ok got a chance to look at the car real quick... I don't belive I have a full throttle switch? If it's just like on a G60 I don't have one. Car has no o2 at all and I'm not sure wich extra wire should go to it. 
I took a a pic of my TB. Also I took some pics of some plugs that are not pluged in. If anyone could tell me what they are for or wear they go that would be great. http://forums.vwvortex.com/zer...82817
MY TB











_Modified by TWIZTD R32 at 1:55 PM 12-24-2009_


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## GeekWagens (Oct 7, 2009)

*Re: How important is a o2 sensor?? (TWIZTD R32)*

Running w/o a O2 sensor could cause your engine to explode and kill everyone in a 5 mile radius!


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## TWIZTD R32 (Feb 21, 2009)

*Re: How important is a o2 sensor?? (GeekWagens)*


_Quote, originally posted by *GeekWagens* »_Running w/o a O2 sensor could cause your engine to explode and kill everyone in a 5 mile radius!

Is that with a full tank of gas?...lol


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## ultravw (Oct 27, 2009)

*Re: FV-QR (TWIZTD R32)*

Looks like no switch on that one. Before I go any further let me ask if your car has a frequency valve. When the engine is running you will here a buzzing sound coming from the fuel distributor. Usually a large throttle body uses an adaptor on these early manifolds unless the manifold has been welded and machined. I have pics of all this I will post Saturday.


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## Glegor (Mar 31, 2008)

*Re: FV-QR (ultravw)*

i thought the frequency valve was back under the intake manifold?


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## ABA Scirocco (May 30, 2001)

*Re: FV-QR (Glegor)*

The thing under the intake manifold is the auxiliary air regulator, it's just a valve, it's open to begin with and closes slowly after you first start the engine it's function is to provide extra air to the engine during warm up. 
The frequency valve is the part indicated in red on this picture.


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## TWIZTD R32 (Feb 21, 2009)

*Re: FV-QR (ultravw)*


_Quote, originally posted by *ultravw* »_Looks like no switch on that one. Before I go any further let me ask if your car has a frequency valve. When the engine is running you will here a buzzing sound coming from the fuel distributor. Usually a large throttle body uses an adaptor on these early manifolds unless the manifold has been welded and machined. I have pics of all this I will post Saturday.









It does have a Frequency valve but the PO had it unpluged, I pluged it in yesterday but only started it and took Cold start video also took a video of pumping the brakes like you had sugested in the Cold start issues thread. Havn't driven the car anywhere yet no inspection so I try to limit my driving..lol
This thread has plugs that are not conected under my hood.
http://forums.vwvortex.com/zerothread?id=4697386
The PO said the car had a larger intake Mani and larger TB that is portmached to the mani. But other people tell me that is the stock GTI mani....? so I'm not sure.
I apreciate the help







, the PO did stuff I'm just trying to see if they were good things... so far... not really...lol But as it sits the car runs great, I really have no complaints, only issue with it now is cold start and my MPG is 20. when I first got the car timing was at 16 Deg advanced, I thought that was much cause the PO had said he had it at about 9 and the sticker under the hood says 6-9 I think. I retarded the timing to 8.3, but after talking to other 1.8 guys they say 16 is fine. So I think that could be my MPG issue there cause the car was getting better MPG of it's cause I was running fuel injector cleaner in the first 3 tanks so maybe that had something to do with it?
^^^^^^ Just trying to give as much info as I can^^^^


_Modified by TWIZTD R32 at 7:12 PM 12-25-2009_


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## ultravw (Oct 27, 2009)

*Re: FV-QR (TWIZTD R32)*

The full throttle enrichment switch mounts like these photos:


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## TWIZTD R32 (Feb 21, 2009)

*Re: FV-QR (ultravw)*

ahh I see... so I belive that the plugs in this pic go to the full throttle enrichment switch .









Is there anywhere I can get a new one or do I need to search for a used one, I'm going to need the bracket too.


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## ultravw (Oct 27, 2009)

*Re: FV-QR (TWIZTD R32)*

I have been trying to find the best used ones I can since the part is NLA. The A2 cars use one that can be fitted by separating the idle and full throttle switches and solder on two blades to accept your connectors. Your throttle body has a port that may interfere with the bracket.


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## ABA Scirocco (May 30, 2001)

*Re: FV-QR (ultravw)*

For a long time, the WOT switch on my car was one that I scavenged from an old photocopier. The type of microswitch used for the WOT switch is a VERY common limit switch used in all sorts of equipment so, print out a picture of the WOT switch, take it down to a local electronic part supply and they WILL be able to help you out. 
This is the sort of thing I'm talking about. There are literally 100's of similar switches available by dozens of manufacturers, this particular one's $5 at digikey.











_Modified by ABA Scirocco at 9:20 PM 1-2-2010_


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## TWIZTD R32 (Feb 21, 2009)

*Re: FV-QR (ultravw)*


_Quote, originally posted by *ultravw* »_I have been trying to find the best used ones I can since the part is NLA. The A2 cars use one that can be fitted by separating the idle and full throttle switches and solder on two blades to accept your connectors.* Your throttle body has a port that may interfere with the bracket*.

I was wondering if it would be in the way.


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## TWIZTD R32 (Feb 21, 2009)

*Re: FV-QR (ABA Scirocco)*

hmmm I'm not sure if there is anything around me like that.


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## MFZERO (Mar 13, 2002)

*Re: FV-QR (TWIZTD R32)*

http://www.digikey.com/


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## TWIZTD R32 (Feb 21, 2009)

*Re: FV-QR (MFZERO)*


_Quote, originally posted by *MFZERO* »_http://www.digikey.com/

I was just about to edit my post cause I googled and found the site.. Your to fast for me..lol
Thanks


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