1.6 hdi maf mystery

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The Gas Man 2
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Joined: 13 Jan 2019, 11:24

1.6 hdi maf mystery

Post by The Gas Man 2 »

Hi.

2008 C4GP 1.6HDI.

Every now and again the engine would go flat, and then pick-up. On disconnecting the MAF the car ran fine (apart from engine light and anti pollution warning).

New RIDEX MAF bought from AutoDoc and fitted and immediately the idle throttle response was very 'jumpy/lumpy' and the flat power delivery came back after a while.

Disconnected it and now it drives 'superb' again, 50mpg, (apart from engine light and anti pollution warning!!!).

Question: Can I run the car with the MAF disconnected? Do you think the new MAF is faulty.

Your valued response appreciated.

doctle
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Re: 1.6 hdi maf mystery

Post by doctle »

I wouldn't drive with the MAF disconnected. Due to several bad experiences with aftermarket sensors I prefer to buy genuine new or at least a known good used one.
I noticed that autodoc has no address or contact number on their site I'd be wary of buying something if I can't ring up if something isn't right.

The Gas Man 2
Posts: 11
Joined: 13 Jan 2019, 11:24

Re: 1.6 hdi maf mystery

Post by The Gas Man 2 »

AutoDoc is a fairly respected on-line parts company with full contact details available. What would be the downside of the MAF being disconnected?

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GiveMeABreak
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Re: 1.6 hdi maf mystery

Post by GiveMeABreak »

The MAF is used to determine the mass of air entering the engine. The engine ECU relies on this information to adapt the fuelling. With the MAF disconnected, either no data or the wrong data will be sent to the engine ECU resulting in too lean a fuel mixture entering the engine. This will ultimately result in excessive black smoke due to overfuelling, which can lead to mechanical damage.

At some point you’ll find the engine ECU will probably go into a backup mode as it detects issues due to overfuelling from other sensor data and increased emissions as a result of the missing or incorrect MAF data. They are essential for modern cars.

Nemo26
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Re: 1.6 hdi maf mystery

Post by Nemo26 »

Check for air leaks before replacing maf. If ecu receives signal in range 0-5V maf works as it should be.

The Gas Man 2
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Joined: 13 Jan 2019, 11:24

Re: 1.6 hdi maf mystery

Post by The Gas Man 2 »

An update.

Against all advice )of which I will probably regret), we have now covered nearly 2000 kilometres in the C4 with the MAF disconnected! The C4 is running well with slightly improved fuel consumption (52 mpg) according to the computer. The engine light is on and we get an initial 'anti pollution system fault', but the C4 drives better and is more economical!

I will keep you updated.

RichardW
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Re: 1.6 hdi maf mystery

Post by RichardW »

Probably the EGR valve is misbehaving. If you get some live data from a decent diag computer you should be able to see it. I imagine EML on will be a C-T fail these days, and is affecting the NOX production, so you should fix it really.... new EGR is not too dear, nor that hard to fit really, given where it is!!