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Discussion Starter #1
Hey,

I am having a fuel consumption problem with my Vauxhall Signum 1.9 Cdti 150 (z19dth). It was working fine until I gave it some right boot last week and it seemed as though something became stuck making the engine use a lot more fuel than usual. Normally uses 0.1 gal/hr warm tick over, after it has accelerated using full throttle (not even to full rpm) the fuel consumption is 0.8 gal/hr!

Even cursing along the motorway at 70 it is not getting the mpg it was previously.

It seems that if I am really careful with the throttle nothing gets stuck open and the mpg remains good.
Also if I stop and turn the engine off, it resets what ever is stuck and mpg is back to normal!!

I have cleaned the EGR, sprayed carb cleaner into the inlet air pipe while running to try and remove any soot/oil that might have built up inside the manifold and swirl flaps and fitted the inlet manifold swirl flap bar back onto the flaps (as that had shaken off). But still if I accelerate faster than a snail the fuel consumption becomes significantly low.

Any suggestions to help, as I'm pulling my hair out!

Cheers guys, look forward to a reply.
 

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Hi, It went into a DPF re-gen - this is the classic sign. It should clear itself though with a good a-road/motorway run.
There is a possibility though that the one of the DPF pressure sensors is malfunctioning. A re-gen happens when the pressure difference between the input gas flow and output exceeds a certain factor.
To re-gen, the system dumps excessive amounts of fuel into the DPF to burn and raise the temperature in the DPF to rid it of particulates. If the run isn't long enough to complete the process it will re start on the next run.
 
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M32 Gearbox Specialist
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fitted the inlet manifold swirl flap bar back onto the flaps (as that had shaken off)
It pops off because the flaps get stuck in the manifold due to carbon build up. It will come off again unless the manifold is cleaned/replaced/modified
 

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Discussion Starter #5
Thanks for the quick reply. I drove it 220 miles Sunday so I'd have thought that run would be long enough. Saying that the swirl flap bar wasn't fitted. I'll be driving it again tomorrow so hopefully see some improvement.

I'll get in the garage tonight and check out those points.
 
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