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Walesy

Lamb Probing?

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Bonjour

 

I've recently aquired a new G60.

 

I bought it last thursday night and have done very little driving in it....i took it to Longlife for a new exhaust on saturday, whilst in there they noticed that the lamba sensor looked a bit knakered and was dangling off...not pluged in....so they rang me and said that they would replace it.

 

I picked the car up on saturday avo and did about 10 miles in it..not really testing it, just getting it home.

 

Then yesterday i went for a little pootle in the evening....and it felt a little sluggish (( hard to tell cos ive only done a few miles in it )) ....then my g/f asked the typicaly g/f-ish thing to ask " whats the mpg in this one then? "....i hadnt looked at it up untill then...but when i flicked it over it was saying 17 mpg!!!!...and thats on a long run!!!!...

 

I must admit i did'nt look at the mpg before that point...but i could only assume that they had messed up my lamba sensor.... so i rang Longlife this morning and explained....ive just been down there and they have removed the sensor and put a blank plug in instead....they reckon my car was running without a lamba sensor beofre it went to them....so they said to try it without one and if the car ran fine they will refund me. Ive just got home and the mpg is saying 13 mpg (( around town figure! )) and i'm pretty sure that my fuel gauge is backing that up.

 

so .....i'm pretty confused now. I'm not sure if my car was running this badly on fuel before i took it to Longlife....so therefore dont know if they are to blame.....and i also dont know why my car is overfuelling.....it seems to run a little better since they removed the sensor this morn...weird......

 

so any suggestions fellas?...........pleeeeease? :(

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Wow 17mpg thats great wish mine did that! only kidding, if the lambda was not plugged in there maybe some other funkyness going on maybe the blue temop sender is shot swap it with the black one right next to it. whats the idle like? g-man is yer man reall but hes a way from you.

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the idle's fine....

 

sorry...not familier with the blue or black temp sender.....where are these?

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You need that probe in the exhaust mate. My mk3 16V had a bypass pipe fitted by some chimp. The probe was tyrapped to the heatshield. It did 30 if you drove like a nun. I was like that for about 3 months. I discovered this while fitting some suspension to it.

Anyway, I had a cat in the garage from my GTI G60 so I knocked the guts out of it and fitted it. Obviously sticking the probe in at the same time. The car now does 40 with relative ease and I got 33 on a 2.5 hours trip from the middle of London home last weekend. Which is 200 miles.

 

For the MPG I would suggest you monitor it over a longer period of time. You shoulos at leats zero it. If they had it ticking over for any length of time it will have made4 a big impact on the reading.

 

It would run badly without the probe connected for sure.

 

You need a working probe in the exhaust, maybe having the new one back in if you can justify the money. Or get yours back if it didn't go in the bin.

 

It is more likely IMO that the wiring has got damaged preventing it working.

 

You can check the output of a probe with a DVM on volts. Hook into the purple/lilac coloured wire which is the signal. As the probe warms up you will see that the meter cannot hold the voltage as it should be changing constantly. If the output is static then its not working. An A/F ratio meter is perfect for monitoring the output of a lambda probe.

 

Gavin

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It would run badly without the probe connected for sure.

 

this is what i dont get...its not connected.....but the car doenst fell lumpy at all..if anything it feels better now than it did when the lamba was plugged in this morning.....

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Bill good call on the BTS too. But that probe has got to go back in.

 

The cat makes no odds. The probe just monitors the gases going past it.

 

Gavin

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You need a working probe in the exhaust, maybe having the new one back in if you can justify the money. Or get yours back if it didn't go in the bin.

 

ok...fair point....

 

so have it put back in ...and then try and find the reason for it not working......i havent got any electrical testing equipment whatsoever...and if i did...i wouldnt know how to use it! :oops:

 

looks like i'm gonna have to take it to an autoelectrician....hopefully they will be able to tell me why the wiring for the sensor aint working! :?

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I'll talk you though checking it if you want. Buy the cheapest digital volt meter you can. Netto had one for 2.99 a few weeks ago, I keep one in the car.

You just stick the red probe down the side of teh wire in the plug and earth the black probe. Run the engine and tell us what happens. A lot less than £30 an hour.

 

Gavin

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Not having a lambda wont affect the MPG reading on the MFA anyway as it only works from manifold vacuum which would be the same if it was connected or not.

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No, but the point was that if you don't have a lambda your fuelling will be way out and WILL effect the MPG ..

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right....would i be right in assuming that the broken pipe in the pic below could have something to do with whjy my car is running like sh1te?...

 

I have ordered a new one from the stealers...it'll arrive tomorrow (( thats the way it is in the village! )) because its broken...but it would be nice to know that it will solve my overfuelling problem

 

 

thanks as always...

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That will be why your MPG is on 99 - try blocking it off for now but I have a feeling it won't affect the running to much...

 

The new one BTW goes all the way back to the brake servo (one big pipe)

 

Suprised you don't know more about Lamb sensors, living in Wales...

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Yes, sorry I remember now mine was on 13 I think when it broke, like I said block it for now so it's not sucking in unmetered air, It will help but you need to sort the probe out..

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that thin black plastic pipe is the one that feeds the back of the clocks with the vacuum so the MFA knows what's going on... :roll:

 

Also, with it disconnected, you've got a vacuum leak which will make the car run like a sack of cack...

 

Get it replaced and see what the car's like then... ;)

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cheers..will do......i got my fingers crossed that it'll sort it.

 

 

 

 

 

 

 

 

 

 

 

 

and stop playing with my post tiltes. :wink:

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DO NOT always trust the MFA, the only true way to measure your fuel consumption is to brim the tank, let it run down and re-fill. My MFA was showing I was averaging 19mpg for ages when I knew I was doing in the region of 30 mpg - checked all the pipework and eventually discovered a tear in one of the pipes controlling the MFA

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