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[TheBoy]

More I think about it, I keep coming back to MAF.  Be nice if any other 2.5 owners can get a MAF kg/hr reading at idle, AC off. I always thought a 2.5 should be around 11-12kg/hr with A/C off.

[JamesV6CDX]

More I think about it, I keep coming back to MAF.  Be nice if any other 2.5 owners can get a MAF kg/hr reading at idle, AC off. I always thought a 2.5 should be around 11-12kg/hr with A/C off.

From memory, that sounds about right... while since I had a baby V6 though 

[Webby the Bear]

Cheers guys. Sorry what is wadding? And I'm presuming that if the exhaust is blocked then that could be why jaime got lazy o2 sensor readings?

[tunnie]

Cheers guys. Sorry what is wadding? And I'm presuming that if the exhaust is blocked then that could be why jaime got lazy o2 sensor readings?

Padding in the zorst to reduce noise 

[TheBoy]

Cheers guys. Sorry what is wadding? And I'm presuming that if the exhaust is blocked then that could be why jaime got lazy o2 sensor readings?

Lazy readings are due to lazy lamdas.

[albitz]

Ime if the exhaust has been blocked by wadding you will know something is badly wrong.My car lost at least half its power when it happened. I struggled to get to 70mph up the M11 and daughter got to Stansted too late and missed her flight - which went down well.

[Webby the Bear]

ok thanks. So could the blocked exhaust contribute to fuel loss in addition to the lazy lambdas? sorry just trying to get my head around it :-) ps re the maf i could chuck Ralfs on and see if that improves things? :-)

[tunnie]

Exhaust blocked also saps power, so engine has to work harder = more fuel used

[TheBoy]

ok thanks. So could the blocked exhaust contribute to fuel loss in addition to the lazy lambdas? sorry just trying to get my head around it :-) ps re the maf i could chuck Ralfs on and see if that improves things? :-)

Leave it a day or so before changing MAF, see if any 2.5 owners can get a reading first

[Webby the Bear]

ok brilliant cheers for that. Almost forgot the one simple thing you asked me to do lol. The inst. Con readings were very iratic but stayed mostly at around 45 mpg

[henryd]

Is it getting up to temperature?

Yes - both gauge and ecu CTS

What about intake air temp sensor readings?

[Darth Loo-knee]

When I had my stainless exhaust fitted it was although I just broke free from towing a tractor or something....the exhaust must have been so blocked..
Maf was the original problem on my car. Convinced it then shafted my exhaust plus O2 sensors

[Kevin Wood]

I'd regard that MAF reading as low on a 2.6. Not had much cause to worry about MAF readings on non DBW engines though.  Different matter on 2.6s.

High idle trim might back up low MAF at idle, but trims look OK at partial load, which is where the economy will get hit. I take it there are no signs of an air leak?

High MID fuel consumption suggests injector duration is high, and, if backed up by real world consumption, the engine is either running rich, more heavily loaded or not running efficiently. That could be down to timing out, blocked exhaust, air leak into exhaust system or lambda sensors. Is it remaining closed loop at all times when it should? Excessive consumption while the trims stay normal favours blocked exhaust or timing out, IMHO.

The following might be useful:
Compare MAF at hot idle with another 2.5
Compare injector duration at hot idle with another 2.5
Try a CO meter in the exhaust and see if the emissions are to pot.

[dbug]

Try running it with MAF disconnected for a while - just unplug it

[Webby the Bear]

Morning guys,

Once again thanks for all the input to this puzzler. Real awesome to see some real diagnosis especially for me wanting to go in to the field

Ok, I'm in danger of being boggled by science here. So just to recap, I should be taking the following action:


• Awaiting the results of anybody else who can compare the 2.5 readings with theirs. Not really too sure if there's going to be many offers as presumably they'd need a TechII to get the readings? 
• Pop a marigold on to the end of the exhaust and test whether it fills up and blows off within a few seconds. This will indicate a blockage and I'll feed back the results tonight hopefully
• Swap out fuel filter and air filter and routine service (due anyway)
• Unplug MAF and run without to see if economy gets better
• Replace O2 sensors. I will do this but I'll have to get use the college ramps. Can i blowtorch these if plus gas not working? don't like the idea of burning residue from a chemical but you can tell me if ill kill myself or not 

Thanks guys, you're all stars!