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frenchy1972
29-01-2010, 11:21 AM
Sharan 2.8 petrol 1997. Engine cuts out when driving when hot and when stopping at junction, at same time heating seems to packup and only blows cold air, have replaced all three temerature sensors which was only fault showing on test meter. could this be air flow sensor and how do i test it? or any other suggestions very welcome, wife nagging about heater.

Carouser
29-01-2010, 07:05 PM
Hello Frency

I've recently had the airflow sensor replaced on my 2.8 VR6.

Symptoms were the car was hesitating when accelerating when crusing, with a notable mis-fire.

It took the garage a long time to diagnose this, (initially thinking it might have been a gunked up accelerator butterlfy), as it was barely noticable at first but got gradually worse to the point where I lost all power and it wouldn't pick up at all.

It did, however, start and would idle, but on occasion would stall.

Initially, no fault codes would come up on the diagnosis equipment, but finally, when it was at its worst, some codes came up all pointing to the air flow sensor.

It would be easy for to get this checked. The socked for the diagnosis machine is underneath the ashtray in the centre consol (you have to lift the entire thing out including the ashtray housing).

Alternatively, although this doesn't necessarily confirm whether the air flow sensor is at fault or not but is simple to check, is to disconnect the sensor altogether. The garage told me when trying to find the fault that sometimes the car would run better with out an air flow sensor at all than with a faulty one.

If you open the bonnet and look to the very top left of the engine bay, you should see a big black box which houses the air filter. Right at the very top, under the driver's windscreen wiper you'll find the sensor, and the electrical plug and wiring. Try unplugging it and starting the car. If it runs better then it is likely to be the sensor, but I stress, this is no guarantee and only what I was told.

If you end up needing one, I paid about £70 for the sensor plus an hour's labour.

I'm not sure about the heating issue though or how this might be linked. Generally it is because the coolent level is too low, so no water getting to the heater box. I suffer from this too sometimes, but then my VR6 needs topping up at least once a month. Something to keep an eye on as these aluminium heads need to keep cool, particularly since they are such a big lump in what is considered to be a very small space!

I hope this helps... Do let me know how you get on.

Best wishes

Carouser