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MG MGF Technical - Lambda Wiring
| This is probably directed at you Will. Do you know the function of each of the 4 wires coming from the Lambda sensor to the wiring harness. I need a new sensor and have sourced a 4 wire item from Emerald but need to know which wire to splice to what.... Of course anyone else can answer too. Tim |
| tim woolcott |
| Unfortunatly not, I know how it works! but not which colour does what. are the wires to the Lamda diffrent on the one you pulled? |
| Will Munns |
| The lamda sensor consists of a heater and a form of temp sensor: http://www.mgfcar.de/schedules/sb8.jpg indicates that the Lamda comes with two white wires, a sliver wire and a black wire, the two white wires are the heater element, and cam be connectec either way around white->blue/red stripe (+ve feed) white->black (GND) The temps sensor should be connected the way you are not expecting! Black -> silver Silver -> Light green /silver stripe This is the same on both VVC and MPi |
| Will Munns |
| Well, At the moment I don't know what colours the new sensor has all I know is it's not a Bosch item but is will fit and it has four wires (like the Bosch sensor) so I'm really pre-empting the question. The reason for trying this is because of a £100 difference in price..... OK, who else want's a stab at this question..... |
| tim woolcott |
| Cheers Will...... perfect intel' Tim See, I knew you could do it.... |
| tim woolcott |
| Tim, how soon do you need to know? I could slap a osciliscope on the lamda and find out the signals for you. but it requires A) me to pic up the scope from 'random stranger' (possibly tonight) B) me to connect the Lamda to the exaust (posibly tonight) have enough time to connect the two together! |
| Will Munns |
| Two wires will be to the heater and two to the actual sensor - the two heater connectors will have low resistance, probably same in both directions. the sensor will have very high resistance. AFAIK sensor is not sensitive to polarity ( 3 connector sensor probably is tho') |
| Steve |
| Steve, I seem to think that the sensor is 'just' a piece of resistance wire, and the resistance varies with temp, but this doesn't tally with another thought that the sensor gives out voltages in the range of 1 volt.... more investigation required! |
| Will Munns |
| looks like I am wrong about the sensor part, it's a ceramic which reacts with oxygen ions in some way: http://www.picotech.com/auto/waveforms/lambda_titania.html |
| Will Munns |
| Although this is more like what I had in mind with the "1 volt" http://www.picotech.com/auto/waveforms/lambda_zirconia.html |
| Will Munns |
| Tim, the ceramic part of your old sensor looked intact: is the present sensor still working??? I agree though - sans metal outer shroud, it certainly needs replacing... What a fun job to look forward to. Not. |
| Rob Bell |
| Now you've lost me..... I'm pretty sure that the sensor is a ceramic type. The little perforated cap has come off the end and there is a ceramic tip showing. How does this affect the wire connection you gave earlier off Deiters site....? I only need the info for the weekend really. Steve & Will, are either of you coming to G-Force this weekend...? |
| tim woolcott |
| So is this Bosch sensor a Titania sensor - as Will has outlined, or the older ZR-O2 type ? Either way, I'm probably wrong about the sensor part being insensitive to polarity - it looks like there is an inner and outer surface to the sensor so this may affect the connection. Looks like the 'scope will give the answers ! |
| Steve |
| So in laymans terms how does the Lambda work then.... The tip is heater and this ionises the gas and somehow adjusts the fueling to a closed loop thingy ..... As you can tell I have little clue...! |
| tim woolcott |
| The Ceramic is some type of catalyst, above a certain temp it reacts with Oxygen (ions?) and creates a voltage, I am pretty sure this voltage is between 0 and 1volt for the Bosch sensor, the website I gave shows between 0 and 5 volts for one type and 0 and 1 volt for the other. The heater will be non-polorized (two wires the same colour most lightly). The sensor should then give off a voltage between 0 and 1 volt, any more and it will be incompatible, I will try and find out which wire is the +ve side. This will only be required if the colours don't match up. |
| Will Munns |
| Picture from Encyclopedia Britannica: http://www.obd-2.de/pics/08.gif - It kind of shows the principles of the Lambda sensor quite nicely. Explanation of the Lambda sensor in rather more detail here: http://www.flash.net/~lorint/lorin/fuel/lambda.htm |
| Rob Bell |
| also how stuff works http://auto.howstuffworks.com/question257.htm |
| JohnP |
| Some information on how to simply test the Lambda at the bottom of this interesting page: http://www.users.bigpond.com/jack_stands/automotive_advice/fuel_injection/efi_repair_2.html Certainly saves on having to use an oscilloscope - if ultimately less informative! ;o) |
| Rob Bell |
| Rob both have similar test routines: yours says "A toot up the flute with LPG" while mine says "Artificially enrich the fuel mixture by directing propane into the intake" your site sounds more user friendly :-) |
| JohnP |
| Absolutely brilliant information... Thanks I particulaly linke the line off Rob's last link "If it has zero voltage out it is indicating lean or it is out of range(stuffed)." That is getting back to the kind of terminology I like and understand. My Lambda sensor certainly fits into this 'Stuffed' category. There is no housing at all and all I see is the ceramic core. That might explain the reason it's running rich up to 5000 and then goes a bit lean. It'll also explain why the car is popping when I lift off before the engine has warmed up..... Looks like 30 quid well spent (as long as I can splice it in correctly and more imporatnly get the old one out again. Rob knows the buggereation we went through last time. |
| tim woolcott |
| LOL John! BTW just come across this site - looks to be something similar to the in-car Lambda sensor that Carl put together: http://www.pelicanparts.com/techarticles/mult_air_fuel_monitor/mult_air_fuel_monitor.htm I think I could live without the sinusoidally laid out LEDs though... ;o) |
| Rob Bell |
| >> Rob knows the buggereation we went through last time. << Oh but wasn't it worth it? ;o) ;o) No, guess not! ROFL If you've never played around with your exhaust manifold, you'll never know how flippin' tough a material these things are made of... |
| Rob Bell |
| If you've never played around with your exhaust manifold, you'll never know how flippin' tough a material these things are made of... Metallugists are still trying to find the source of the material, they think it's from the planet Kypton. And what is more it is over engineered in this material too....... |
| tim woolcott |
| Kypton? Is that a town on the south coast? ;o) |
| Rob Bell |
| <<Kypton? Is that a town on the south coast? ;o)>> No. It's a bed! Think about it....:¬) Bruce |
| Bruce Caldwell |
| May be the test routine for the installed Lambda may help you comparing with the one you have. I took this from Carl to my *growing* under construction Sensor site at: http://www.mgfcar.de/sensor or just cut (the same is in the archives): -------- How to test: The 2 connectors on MEMS-2J for VVC have their cables visible, ie. not fully covered with black tape. Find a GREY and a striped LIGHT GREEN /GRAY. These are from oxygen sensor. With a Digital voltmeter (10MOhm input) set at 2 Volt range You can measure voltage from sensor . Have someone to read voltage when slowly passing thru rev. that causes the slight hesitation. Does voltage take a low dip in 0,4-0,2 V region? This means fuel starvage due to some reason like fuel pressure reg. fault or dirty filter. Possible is of course also injector problem but should be detected at TestBook-run. By slowly acc. the Mems will be "in loop" and all fluctasions from oxygen sensor seen. The best instrument is a combined digital and bar readout. I have wired a permanent connector to these 2 wires so I can check oxygen sensor output easily. Rich mixture=0,8 - 0,9 Volt. What catalyst wants = 0,5-0,7 Volt. Lean mixture 0,0 - 0,4 Volt. During normal driving oxygen sensor voltage will swing between extreme voltages, this is the nature of this servo system. Try to detect average reading, not so easy on Voltmeter without bar-graph. NEVER use ordinary analoge voltmeter, it loads sensor too much! (Carl) --------- Regards Dieter |
| Dieter K. |
| Nice one Bruce ;o) Dieter, nice description of the testing procedure :o) One thing I was a little unclear about - when attaching the voltmeter to the sensor cables, do you have to bare the wires? I'd be a little nervous about doing that... :o( |
| Rob Bell |
| >>when attaching the voltmeter to the sensor cables, do you have to bare the wires?<< I've not got good connections from anywhere else - the back of the plug /socket is normally blocked. best tool I've found is like a thin pin-like probe that goes through the insulation without any cutting. As for measuring with a DVM, you can get an adapter (maybe called a peak-volt adapter) to give a repeatable reading. |
| Steve |
| >>best tool I've found is like a thin pin-like probe that goes through the insulation without any cutting.<< Yup - I think that that is the best way to go Steve. I've heard about these probes, but not ever seen them for sale: a Maplin's catalogue item? |
| Rob Bell |
| >>but not ever seen them for sale: a Maplin's catalogue item? << Maplin's don't have them in their catalogue; although they do have the type that clamp to a cable. I've only seen them included with a 'scope or upmarket DVM. I need a pair for my cheap 'scope ! I've been looking at various shows etc, but without success. |
| Steve |
| Let me know if you do ever find some Steve :o) |
| Rob Bell |
| Errr, just use any needles from *mothers* sewing case as adaption ;) Or buy an expensive shirt. They are packed with needles. Push through the cable isolation with help of a gripper and there you are. Standard DVM gripper clips to be connected to the needles then. High resistance Voltage input from a DVM will not put any reasonable load on the tiny signal. A fast analogue *Rohrenvoltmeter* (spelling) with arrow indication shows tendences much better, though. Cheers Dieter |
| Dieter K. |
| LOL - okay, a set of cheap sewing needles it is then! :o) |
| Rob Bell |
This thread was discussed between 30/09/2003 and 03/10/2003
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