How to get a free exhaust gas analizer! - VW Forum - VZi, Europe's largest VW, community and sales
 


     
 

Go Back   VW Forum - VZi, Europe's largest VW, community and sales > Tech Forums > Aircooled Mechanical Tech > Tech FAQ archive

Tech FAQ archive Useful and frequently asked tech questions. Mods, please move FAQs into this archive.

 
 
Thread Tools Display Modes
Old 28-06-2005, 01:48 PM   #1
AngelVenomous
Help! I'm trapped in here
 
AngelVenomous's Avatar

Trading feedback: (0)
 
Join Date: Dec 2001
Location: Northumberland
Posts: 21,255
Default How to get a free exhaust gas analizer!

(Although you do need a multimeter that can read from 0.1 to 1 volts)

Just go to a scrap yard, take the lambda probe/oxygen sensor (whatever you wanna call it) from a modernish car, stick it in your pocket, run away from the Alsations and the scary guy in the caravan.

Two ways you can fit it to your Bug, either drill a hole in the exhaust (need to be a section that warms up quickly) slightly smaller than the sensor and tap it so the sensor fits and seal it with exhaust putty. Alternatively get a spark plug adapter that will accept the sensor and weld the adaptor to the exhaust.

Now the exciting bit, run the engine until warm and connect the multimeter to earth and the main wire on the sensor.

The reading mean as follows:
0.7V = 13:1 - ideal for HP and exhaust valve cooling
0.45V = 14.7:1 - ideal for cat converters
0.3V = 16:1 - you are about to put a massive hole in your pistons!

Also, at wide open throttle you should get 0.8V but if it suddenly drops to 0.5V then your engine is leaning out at high revs (happens particularly with Weber IDFs or Dells)

There is of course nothing to stop you having a volt meter on the dash that will tell you as you're driving along (as long as it's calibrated for 0.1-1 volts)
AngelVenomous is offline  
Old 28-06-2005, 02:06 PM   #2
VielziDub
Help! I'm trapped in here
 
VielziDub's Avatar

Trading feedback: (0)
 
Join Date: Jan 2003
Location: Nessieville (Drumandrochit)
Posts: 11,626
Default

That's very usefula nd interesting! Where can I find one of these lambda probes? Are they stuck on modern car exhausts? Where abouts?

Cheers,
Dan
__________________
SEX: The Breakfast of Champions
Team Lost Baja
VielziDub is offline  
Old 28-06-2005, 02:20 PM   #3
garethj
25 character limit is cra
 
garethj's Avatar

Trading feedback: (0)
 
Join Date: Mar 2002
Location: Bedfordshire
Posts: 6,644
Default

Quote:
Originally Posted by AngelVenomous
The reading mean as follows:
0.7V = 13:1 - ideal for HP and exhaust valve cooling
0.45V = 14.7:1 - ideal for cat converters
0.3V = 16:1 - you are about to put a massive hole in your pistons!

Also, at wide open throttle you should get 0.8V but if it suddenly drops to 0.5V then your engine is leaning out at high revs
Wow, really handy tip!

Dan, the lambda probe will be somewhere on the main exhaust section underneath the car, around the catalytic converter.
garethj is offline  
 
Old 28-06-2005, 02:25 PM   #4
DarkHorse
Help! I'm trapped in here
 
DarkHorse's Avatar

Trading feedback: (0)
 
Join Date: Sep 2004
Location: Where? Ware
Posts: 8,963
Default

Quote:
Originally Posted by AngelVenomous
stick it in your pocket, run away from the Alsations and the scary guy in the caravan.
__________________
Asta x
DarkHorse is offline  
Old 28-06-2005, 03:09 PM   #5
jap
I'm not an addict... honest!
 
jap's Avatar

Trading feedback: (0)
 
Join Date: May 2004
Posts: 5,959
Default

look at an old astra just behind the rad where the exhaust goes from 4 into1 its there 20mm spanner

or there new from partco for about 16-20 quid

jap
jap is offline  
Old 28-06-2005, 03:28 PM   #6
AngelVenomous
Help! I'm trapped in here
 
AngelVenomous's Avatar

Trading feedback: (0)
 
Join Date: Dec 2001
Location: Northumberland
Posts: 21,255
Default

All UK production cars built after 1992 will have a lambda sensor.

Most cars seem to have it in the exhaust manifold just after the four exhausts from the cylinder go into one (usually behind the radiator as Jap says)

A new one might be an idea although I'm a tight git! When getting scrap ones I always get a few and test them over the gas hob with a pair of pliers to make sure I get a voltage (it'll proberbly say between 0.9-1 volts due to all the oxygen that will be around)

Couple of other things too - the easiest ones to use are the 1 wire sensors, the body is grounded through the exhaust. Some other sensors may have 2, 3 or 4 wires. This is usually for a heater connection so the sensor can get at maximum temp quickly. I personally wouldn't bother as it's only more strain on the electric system (particularly if you've just started your car from cold!) but you can if you wish.

If you're not gonna bother with the heater on a 2, 3 or 4 wire sensor and don't know which wire to use, again do the gas hob test mentioned earlier and test all wires to see which one gives off the voltage.
AngelVenomous is offline  
Old 28-06-2005, 03:32 PM   #7
Paul Weeding
Lord Von Hannover

 
Paul Weeding's Avatar

VZi Member Sponsor

Trading feedback: (9)
 
Join Date: Apr 2002
Location: Newcastle
Posts: 20,586
Default

top tip... i shall consign this to the tech archive in a few days!!
Paul Weeding is offline  
Old 28-06-2005, 03:38 PM   #8
sam_cat
I really must get out more
 
sam_cat's Avatar

Trading feedback: (4)
 
Join Date: Jun 2002
Location: North of Bristol, UK
Posts: 7,478
Default

Ebay is a good source.
I have a brand new posh 4 wire Wide band one sat at home that was an ebay win, along with LOTS of useful links (which I will post when I get home).

Cya,
Sam C
sam_cat is offline  
Old 28-06-2005, 03:46 PM   #9
AngelVenomous
Help! I'm trapped in here
 
AngelVenomous's Avatar

Trading feedback: (0)
 
Join Date: Dec 2001
Location: Northumberland
Posts: 21,255
Default

Quote:
Originally Posted by Paul Weeding
top tip... i shall consign this to the tech archive in a few days!!
OOH! Thankyou! Bloody hell, I've said something useful on here!

BTW, if anyone is thinking about putting a volt meter on the dash, use a very thick wire to minimise resistance.

VU meters from old audio equipment might be an idea as they usually only read a few millivolts. You might have to calibrate it with a multimeter and write on "lean, correct, rich" at the appropriate points though.
AngelVenomous is offline  
Old 28-06-2005, 05:30 PM   #10
AngelVenomous
Help! I'm trapped in here
 
AngelVenomous's Avatar

Trading feedback: (0)
 
Join Date: Dec 2001
Location: Northumberland
Posts: 21,255
Default

Another hint - if you've got twin carbs why not fit two?! Each one just after the exhaust flange (sorry, I love that word!)

You could even use summat like this to display the mixtures from each carb:

http://img-europe.electrocomponents....C348844-01.jpg

Of course, if you've got twin choke webbers or dells you could even fit FOUR!!!
AngelVenomous is offline  
 

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT +1. The time now is 09:49 PM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.

Disclaimer: For recreational purposes only, some assembly required. Any resemblance to real persons,
living or dead is purely intentional and the site admins are not responsible for direct, indirect,
incidental or consequential ridicule resulting from any defect or failure to perform. No animals
were harmed in the creation of this forum. Colours may fade over time. No other warranty expressed or implied.

volkszone.com

SupportingSupporting Brad's Cancer Foundation

 













 
© Volkszone • Terms and Conditions of use