MPG Vs. Thermostat = WTF??? - Alfa Romeo Forum
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(Post Link) post #1 of 3 Old 14-08-10 Thread Starter
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MPG Vs. Thermostat = WTF???

Hi Guys,

what do you recon to this? My '99 2.4 JTD was running at 70 degrees on the dial, got there quick and stayed there rock solid. I thought all was well and that was normal for a JTD. At this stage it was doing 43mpg.

Then I read that it should be hitting 90 like my petrols. So I bought a new thermostat for it, fitted up and bang, 90 degrees on the button, and I expected my mpg might pick up a bit to 45ish since it wouldn't be running in cold fueling mode.

Was I wrong! Mpg had dropped to 39, same commute, same driving style, same fuel. What the heck has happened? Is it likely I've trigger something else now it's running at corect temp? Anyone got any ideas or experience?


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Alfa History: '78 GTV 2.0, '83 GTV6 2.5, '98 156 Selespeed 2.0, '96 GTV 2.0, '96 GTV 2.0, '05 GT 3.2 V6, '96 146 2.0ti, '99 156 2.4JTD, '01 147 1.6 Lusso.
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(Post Link) post #2 of 3 Old 16-08-10 Thread Starter
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Has anyone got a clue on this one?
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Hello, i have an idea.... and i think well 99% sure i have anyway.... Right here it goes get it plugged in to a scanner or diagnostic's equipment and get a live data feed up on the screen watch the temp. on the dash guage and watch the temp on the live data i have a strong feeling thay wont be the same which will show that the coolent temp sensor is still working within paramiters but telling the ECU it's at a diffarent temp which will allter the AIR/FUEL ratio. And with the vehicle now running at OPTIMUM RUNNING TEMPRITURE i'd clean the throttle housing.

Should take you back to where you need to be.

Please let me know the outcome !!!!
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mpg , thermostat , wtf

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