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Low MPG and temp gauge reading low

Posted: Wed Apr 08, 2009 10:47 pm
by steg90
Hi,

Just got a Pug 1.8 Rapier, year 2000, FSH, 87k on the clock, she's in for a cambelt next week.

The problem I'm having so far with her is she is only returning around 24mpg, and that is doing 60mph on the motorway! Getting about 160 miles off
33 litres ( around 7.5 gallons ) on motorway trips - this seems low to me?

Now, the temp gauge seems to read 70 all the time, lowest it can show, could the coolant sensor be faulty and thus the ecu is running the car rich as it
thinks the engine is always cold? If so, where do I locate the sensor?

Many thanks!

Steve

Re: Low MPG and temp gauge reading low

Posted: Wed Apr 08, 2009 10:55 pm
by mjb
Most 406s have 2 coolant temperature sensors - one for the ECU the other for the dash.

More likely you need a new thermostat. If you let the car idle from cold and you feel the radiator slowly warming up, you need a new 'stat. If it stays cold until the temperature hits around 85-90c then suddenly gets hot, it's working correctly

Shouldn't affect economy that much though. Check your air filter's not clogged and your cat's not collapsed

Re: Low MPG and temp gauge reading low

Posted: Wed Apr 08, 2009 11:03 pm
by steg90
Thanks,

Air filter is fine, I checked the other day, looks new. I do know the car needs new pads and discs on the front, whether this has an effect on the mpg?

The car does get warm as I know the temperature in the car is fine when I set it, just the temp gauge stays at 70, thus me thinking the temp sensor for the ECU
is faulty, car running rich all the time maybe?

Dunno how to check the cat? I'm not too mechanically minded :-(

If it is the temp sensor, where is this located?

Many thanks again,
Steve

Re: Low MPG and temp gauge reading low

Posted: Thu Apr 09, 2009 5:28 pm
by steg90
Hi,

Cat is fine, had full exhaust check today. I've no idea why I'm only getting around 25mpg, car idle is fine, tyre pressures
are all fine. I've just had new discs and pads put on the front so maybe this will help?

Cheers

Re: Low MPG and temp gauge reading low

Posted: Thu Apr 09, 2009 7:48 pm
by teamster1975
I'd jack each corner up and check that each of the wheels spin freely for starters.
You say that you've had the front brakes done but the rears may be binding :idea:

Re: Low MPG and temp gauge reading low

Posted: Thu Apr 09, 2009 8:26 pm
by steg90
Hi,

Rears are drums, they do look very, very rusty?

Only had the discs/pads done today, so hoping they might have been binding, fingers crossed.

Cheers,
Steve

Re: Low MPG and temp gauge reading low

Posted: Thu Apr 09, 2009 8:42 pm
by teamster1975
May well be binding on the rears. Fingers crossed it's a cheap & easy fix at any rate! :)

Re: Low MPG and temp gauge reading low

Posted: Thu Apr 09, 2009 8:44 pm
by steg90
I'll take a look tomorrow, so, I just jack each corner up and spin the wheel, if it is binding it won't spin freely?

How much do you think drums are?

Cheers