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MG MGF Technical - MGF emissions

This is a long shot i know but the details i have are very vague as i am typing this on a laptop in my car and the information has been passed on second hand from the wife.

Wifes car p reg vvc just failed its mot dut to high emissions,garage replaced a sensor of some variety which should have fixed the problem and still no joy.
Under closer inspection it seems a wire ? has been removed by a previous owner / garage and when connected trhe emissions go sky high.Any ideas what this wire is , why this would have been removed aling with any other info about the problem.
Jim Bognar

Hi Jim,

Where abouts is the wire coming from?
If it's from underneath near to the exhaust then I would imagine that they are referring to the Lambda sensor which would also explain why they said they needed to replace a sensor!
But surely if this was not working/connected, your wife's dash would have been lit up telling you?
Have you got any more info as yet?
Kris Ford

The replaced sensor is likely to be the Lambda.

The removed wire? Not sure what that could be on a '96/97 VVC? Seems unlikely that anyone would disconnect the inlet manifold temperature sensor...

Jim, could you get more information on the wire/ sensor that has been reconnected?
Rob Bell

And as an afterthought, if a previous owner has had a CAT replacement pipe installed at some point then this may (??) explain someone wanting to disconnect the sensor?
Kris Ford

Kris, pre-2001 MGFs only have one Lambda, and that is mounted on the exhaust manifold at the front of the engine - so I doubt that the disconnected wire is going to be that.

A bit of a mystery! Keep us informed Jim
Rob Bell

Sorry Rob,

You're absolutely right! I forgot about that.
So it would make zero difference to remove it pre-CAT!
Kris Ford

Well, it certainly would have no benefit doing so, as the MEMS would then go to a fail-safe map on closed-loop running...
Rob Bell

cars going to an MG on monday so ill keep you all informed of whats going on.
Guy at the local garage who is usualy brilliant by the way is scratching his head on this one.
Even after spending hours on the problem he refused to take any payment as the problem wasnt fixed,
There are still some genuine ones out there
Jim Bognar

The "F" is very sensitive on leaks along the exthaust system. Even a tiny leak will give too high lambda reading.
Any chance of posting the full report on CO/CO2/NoX etc? / Carl
Carl

here's the info and please be gentle with me as i am i no way tech minded when it comes to cars.
Finally got it sorted , turns out it need a software download ????? and there was a prob with the cat which was replaced previously with a cheap and cheerful model by a previous owner and that has now been replaced with a timax walker cat
Lambda sensor and exhaust were fine with no leaks etc.

Cars back tomorrow with new MOT and omissions sorted.

Got what i thought was a good price but would be interested in what sort of cost inc vat and labour inc the diagnostics you guys think i should be paying .should i be paying for all this
Jim Bognar

This thread was discussed between 26/10/2005 and 01/11/2005

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