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post #15 of (permalink) Old 7th February 2011
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Re: Recent rise in MPG queries

Originally Posted by ourcar View Post
It's just an observation, but there seems to be a rise in members asking about MPG figures, most of which concern suddenly being lower than usual.

Have fuel suppliers been putting in some secret ingredient I wonder ?

I include myself here, but that coincides with me getting a newer car, which I expected to have a better MPG than the old one.
Hello Noname,

I might add an observation here for consideration,, On one plug in diagnostic test by my garage,, it was pointed out that the engine temperature was not running as it should be, it was much to low, this was after driving some 5/7 miles.
I also now notice the visual temperature goes from 5 to 4 bars from time to time after even perhaps 100 miles.

When the diagnostic test was done (none Renault) it was pointed out that the engine management was running a rich fuel intake as a result of it seeing a low engine temperature.

Do you remember the days of automatic chokes (mechanical) which were a pain in the exhaust pipe?

I have also heard others comment that even with new vehicles (same engine) the temperature bars were very slow to lift so could be also iffy!

I have had my thermostat changed and it did seem to have made a marginal difference but not of essential consequence.

The heater is also not the best in the world and I would never get climate control again, never!

I regret I donít put the possibility of a failure of quality control by Renault with regards to near all the (uk if different) thermostats they fit.

Even in 10 plus degrees cent I am doubtful about the ability of the thermostat to reduce the water flow through the radiator thus allowing the engine temperature to rise always fully to its operating temperature.

Now in much warmer weather it may be able to achieve its operation point,,, but this trigger point of its operational cycle is a serious concern to me and until convinced otherwise I intend to follow this up.

Itís no use selling a car which is advertised to deliver certain MPGís when in 4 or 5 or 6 months of a UK year it canít because all the fitted stats are the wrong value.

Some early Montego diesels had a stat problem many years ago,, and we may not have moved forward technically for tens of years with these stats,, apart from we donít have to change the stats for winter and summer use anymore as we used to.

Blocking the radiator grill was one solution to bring the stat back into the control area, but with caution. Not so easy today and not an under warranty solution even if you could get to the radiator sensibly.

Any comments on this appreciated,, please tell me this cant be right and my experiences have been, indeed are, unfortunate.

ST fan

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