Vauxhall Insignia Sports Tourer - MAF Fault?

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Wed 31 Jan 2018 12:48
Vauxhall Insignia Sports Tourer - MAF Fault? - Deryck

I have the 1.8 petrol that put the MIL on this morning. Idle revs went up when brking and dippling the clutch at one point and then had a slightly lumpy idle. There can also be a bit of a whistle under acceleration - I will listen again tonight

I had a look around and cannot see any obvious leaks or splits in hoses. So I then put a code reader on and it came back with P0171 System Too Lean. Disconnecting the MAF gave a nice even idle but braught on the ESP warning lamp.

Questions:

  1. Is the MAF the main suspect or could there be another cause?
  2. I had a oil change service about 800 miles ago and read over-filling could cause a problem on the inlets. Is this likely?
  3. ESP warning light came on with MAF disconnected. Bit strange?

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Wed 31 Jan 2018 18:04
Vauxhall Insignia Sports Tourer - MAF Fault? - elekie&a/c doctor

P 0171 would indicate a possible leak in the intake system,that is why it flags a system lean code. Also check the oil filler cap is seated correctly. These engines can suffer oil breather valve issues which are part of the cam cover. On a lot of modern cars,any engine mil light can trigger an Esp fault.

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Thu 1 Feb 2018 11:10
Vauxhall Insignia Sports Tourer - MAF Fault? - Railroad.

A vacuum leak sounds most likely. Check the crankcase ventilation valve which could be faulty.

On a petrol engine manifold vacuum is present when the engine is running and throttle is closed. That also means that the effect of any leak is more severe when the throttle is closed. Using a scantool check the fuel trim. If the Short Term Fuel Trim figures differ considerably from when the throttle is closed to when it's open then a vacuum leak is the likely cause. Alternatively connect a vacuum gauge onto the inlet manifold and check the reading with the engine idling. You should have around 21in-hg. A steady but low reading would indicate a vacuum leak.

And yes, since the ESP system needs to be able to control the engine as well as the brakes, any existing faults such as a loss of Mass Air Flow signal is likely to trigger a fault or even disable it.

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Thu 1 Feb 2018 12:37
Vauxhall Insignia Sports Tourer - MAF Fault? - Gibbo_Wirral

Very common mistake - MAF shows an error in its detecting. People assume the MAF is faulty and replace!

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Thu 1 Feb 2018 21:25
Vauxhall Insignia Sports Tourer - MAF Fault? - Deryck

I've been looking around a bit! Oily bits are not my field of expertise so all help is much apprecated!

I tried to remove the oli filler cap whilst the engine is running and found quite a vacuum on it. Is this normal? or could this be the breather blocked?

Would you happen to know where the breather hoses are and could they be removed whilst the engine is running to check the effect?

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Thu 1 Feb 2018 22:21
Vauxhall Insignia Sports Tourer - MAF Fault? - elekie&a/c doctor

If you are struggling to remove the oil filler cap with engine running,then is usually a sign that the oil breather is faulty.It is part of the camshaft cover housing.Something like this;www.ebay.co.uk/itm/NEW-CAM-ROCKER-COVER-GASKET-VAU...C

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Fri 2 Feb 2018 18:51
Vauxhall Insignia Sports Tourer - MAF Fault? - Deryck

Well, I found the breather pipe and that seems OK - no splits and was clear of any gunk.

I had a bit of a cloud of blue smoke (just the one) and an acrid smell this afternoon, so the car is in for a diagnostic check on Monday afternoon. It doesn't sound promising to me so I will find out what the problem could be next week. Hopefully it is the stuck PCV valve and not too much more serious now.

I will feed back what I learn.

Time for a new car :-)

Edited by Deryck on 02/02/2018 at 19:15

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Wed 7 Feb 2018 10:02
Vauxhall Insignia Sports Tourer - MAF Fault? - Deryck

If you are struggling to remove the oil filler cap with engine running,then is usually a sign that the oil breather is faulty.It is part of the camshaft cover housing.Something like this;www.ebay.co.uk/itm/NEW-CAM-ROCKER-COVER-GASKET-VAU...C

Yes, it was proved to be the breather as was suggested by others!

I had the car in the garage and it was an interesting conversation after the repair. The engine had had a minor leak around the rocker cover for a while but not too much to worry about. When the cover was removed the seals around the screws in the centre of the cover were so brittle that they snapped.

This led onto a conversation about another Vauxhall with a similar leak some time previously. The garage had tried to get hold of just the seal but were told that it came as a kit with the cover. The reasoning was that if the seal had gone then the valve will not be far behind as it is made of the same material.

I considered buying a cheaper cover but as I may be keeping the car a while I thought I might as well bite the bullet. I have not been 100% convinced by some "genuine" parts I have had from eBay and the like but I've not had problems yet.

This hasn't been the cheapest fix for what had failed but at least the old jallopy is no longer belching blue smoke.

Thanks for the suggestions

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