Poor Fuel economy 20mpgish with my 2.0 16v

[Chay 0]

I was getting 20mpg on my way to Wales and back I had a bike rack on the back but was sitting between 70 and 80. this doesn't seem right, other than checking the temp sensors and the lambda sensor is there anything else I should be checking. The best I have had so far is 330miles to a tank mixing motorway and town driving, and not ragging it the whole time. I am going to get the ECU read and gas test, is this the best way forward? Any help would be appreciated, cheers.

[stevemac 0]

20mpg definitely too low for a 16v.

 

Get the c/o checked - I suspect that the car's running rich. Not sure if your car has a 5th injector (for cold starting), if so - that may be the problem. Possibly caused by a faulty temp sensor - car may be running in "coldstart" mode all of the time.

[saysomestuff 0]

I was getting 20mpg on my way to Wales and back .... but was sitting between 70 and 80.

 

Were you in third? :lol:

[Chay 0]

cheers guys, definetly not in third ( well not all the time), sorry not up on the terms quite - c/o?

[rayb74 0]

Hello Chay ! Welcome to the forums.

 

My car is doing exactly the same Im averaging 280 on a tank with mainly motorway mileage !

 

Stevemac which temperature sender is it ? As far as I am aware I have one which has one wire coming from it and another which is for the temp gauge (does this one also do anything else as it has four wires)

Cheers

 

P.S. Chay I am not sure if CO means Carbon Monoxide reading or Carbon Dioxide (which is CO2)

[stevemac 0]

c/o = exhaust gas emissions. Most garages will have the necessary equipment to check it.

[stevemac 0]

I am not sure if CO means Carbon Monoxide reading or Carbon Dioxide (which is CO2)

CO2 is Carbon Dioxide.

 

So far as I'm aware c/o = carbon/oxygen. It's the ratio between the two which is measured. Some of the more expensive gas analysers will tell you the exact chemical content of the exhaust emissions.

 

I have no idea exactly which temp sensor is for the cold start system on a 16v, but I suspect yours will be dead.

[stevemac 0]

Just a thought - check your rear brake calipers aren't starting to seize, this will also result in low mpg.

[rayb74 0]

Will do thx for info Stevemac !

[corradophil 3]

Chay, Is this based on what the MFA is saying?

 

How many miles do you get from a tank? I get around 400 miles, my MFA shows a long term average of 30mpg and on a motorway run I get 34mpg.

 

If you get similar milage, I suggest you check the small vaccum hoses at the rear of the engine bay. If you have a leak in one of those you will get a bad reading on the MFA.

[flusted 0]

Also bad cam timing can result in very poor mpg

[Chay 0]

yip it's based on the mfa, however I am only getting about 330miles to the tank and also the exhaust is all black soot, this is a sign of running rich?

[bcstudent 0]

CO definitely stands for Carbon Monoxide with respect to exhaust emissions. It's the result of incomplete combustion of fuel. High CO is an indication of a rich mixture (or a misfire).

 

The cold start valve on the 1.8 and 2.0 16v engines is controlled by a thermo time switch (#4 in the picture). On the 2.0 16v the need for cold-running enrichment is signalled by a temperature switch on the flywheel-end of the cylinder head (#3 in the picture).

 

You can test the operation of the cold start valve by removing it from the inlet manifold and making sure it only operates for a few seconds when cranking the engine from cold. The temperature switch can be tested by checking that it changes state between cold and normal operating temperature.

 

If all else fails check the fuel pressure and the differential pressure regulator current as it's these that ultimately determine the mixture ratio.

[ben16v 0]

bcstudent, very useful pic... cheers mate

 

BTW i get 30-34 mpg

[logicaltuning 0]

got the same problem on mine, so i will be checking it tonight, hang on, no i wont, im going on hliday, i'll check it when i get back

 

cheers BCstudent :D

[bcstudent 0]

I must have posted that same picture a dozen times in different threads since I found it on this very forum! I can't remember who to credit for the original picture.

[rayb74 0]

Top post bc student thx! Will check this weekend .....

[rayb74 0]

yip it's based on the mfa, however I am only getting about 330miles to the tank and also the exhaust is all black soot, this is a sign of running rich?

 

Exactly what im getting. Hope you get it sorted. Will keep you updated if I can find a solution Chay.

[Chay 0]

just had the feedback from the ECU read and emissions test and it all comes back fine.....any more ideas!!

[stevemac 0]

Chay, You checked the rear calipers aren't binding ?

[Bally 0]

wow thats not good MPG... like steve said check yr cailpers or for air leaks..

 

myns a 1.8 16v...

 

was averaging this on my way home from northants the other nite!!

 

not bad me thinks :lol:

[gsbellew 0]

Did those with this problem ever sort it?

 

Mine is giving crap MPG, 14 - 20 most of the time, highest ever was 33mpg, it got slightly better with the new exhaust, but its gone to sh1te again, its hard to start and keep running for the first minute or so when cold, then its fine, could this be related?

 

I'm regretting selling my G60, it was more economical :roll:

[kerrinmay 0]

Mine normally averages just over 30 mpg, but I've got as high as 40 mpg before on a good long drive across country. Mind you that was with my Mum following me when my parents moved house last November so I had to stick to less than 60 on the A-roads so as not to lose her!

 

I normally get about 400 miles out of a tank, but think I've had as much as 450 miles before!

[davidwort 0]

Did those with this problem ever sort it?

 

Mine is giving crap MPG, 14 - 20 most of the time, highest ever was 33mpg, it got slightly better with the new exhaust, but its gone to sh1te again, its hard to start and keep running for the first minute or so when cold, then its fine, could this be related?

 

I'm regretting selling my G60, it was more economical :roll:

 

injectors might not be spraying right pattern, cam belt might be a tooth out, you should really be getting close to 30mpg with a mixture of driving,

 

I think I have a near record on mine, 420 miles from a tank, it's a 1.8 with a 2L block, so it has the smaller 55L tank.

 

I filled it to the brim before and after so I know I averaged over 37 to the gallon, it's a new engine now well run in, perfectly set up on the rolling road with standard tyres.

[filski 0]

i once had 40 mpg, but usually it's 30 - 35 mpg.