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excessive petrol consumption- Type S

skhell said:
Great, will do the same B)
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be careful with nuts. Whey are unscrewing hardly. you may damage some. make sure you can get spare one. there is used M10 nuts (1.25mm step) and new one must be manufactured specially for exhaust (not coated or galvanized), because other ones will get rusty(coating is overburning in high temp and bolt with nuts gets almost welded) very much and you will not be able to unscrew them after some time ;)
 
Linas said:
be careful with nuts. Whey are unscrewing hardly. you may damage some. make sure you can get spare one. there is used M10 nuts (1.25mm step) and new one must be manufactured specially for exhaust (not coated or galvanized), because other ones will get rusty(coating is overburning in high temp and bolt with nuts gets almost welded) very much and you will not be able to unscrew them after some time ;)
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Thanx, will have that in mind ;)
 
Digging up an old thread :)

Have you reached on any conclusion on this one?
 
I have also found that with my air con on the fuel economy drops by approx 5MPG.
 
a worn or slack timing belt will have an effect on fuel consumption also.
ive just replaced the auto tensioner on my car as it was slack and replaced it with a ks manual tensioner and my fuel economy has improved and drivability has improved.
im getting around 28 -36mpg on an f20b motor.
i could get more if i got rid of the 17" wheels and disconected the ligaments in my foot :D
 
Daveybee said:
a worn or slack timing belt will have an effect on fuel consumption also.
ive just replaced the auto tensioner on my car as it was slack and replaced it with a ks manual tensioner and my fuel economy has improved and drivability has improved.
im getting around 28 -36mpg on an f20b motor.
i could get more if i got rid of the 17" wheels and disconected the ligaments in my foot :D
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The timing belt should not affect the fuel economy if correctly, thus having the camshaft and crankshaft properly aligned, I guess B)
Probably you didn't have the timing correctly adjusted, thus getting a poor driveabilty and even worst fuel economy.

I didn't knew that the f20b engine had a auto tensioner, thought it was manual, just like in the F18B2.
 
At the moment I am getting about 12/13 L/100km, equivalent to 22/24MPG(uk galons), driving only small 4km commutes on medium city traffic. I guess that is too much.
In the freeway, I get about 8 L/100km (35MPG), which I guess is quite reasonable.

In the next weeks, I will remove the catalytic converter to see if its clogged. Already bought the gaskets.
 
skhell said:
The timing belt should not affect the fuel economy if correctly, thus having the camshaft and crankshaft properly aligned, I guess B)
Probably you didn't have the timing correctly adjusted, thus getting a poor driveabilty and even worst fuel economy.

I didn't knew that the f20b engine had a auto tensioner, thought it was manual, just like in the F18B2.
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it the teeth are worn it allows the valve timing to go out of sync with each cam as there is a looseness where the teeth sit in the pulleys.were talking small measurments but the whole engine is based on small tolerances.
the computer is working overtime to correct these small tolerances and wasting fuel doing this.

if the belt has slack in it the cam and crank timing will be out especially on light loads and feathering the throttle,again the computer will be working overtime.
this scenario can cause hesitations like that of the egr also.
think of belt in your hand with a bit of slack,then pull it apart fast and you could make it snap.theres the delay between cam and crank sync albeit small but it makes a difference.
good tension equals no delay.

the f20b engine has the auto tensioner like the h22 found in the honda torneo sirt ;)
i have my ig timing set at 12btdc so its spot on.

im not great at explaining but maybe you understand B)
 
Daveybee said:
it the teeth are worn it allows the valve timing to go out of sync with each cam as there is a looseness where the teeth sit in the pulleys.were talking small measurments but the whole engine is based on small tolerances.
the computer is working overtime to correct these small tolerances and wasting fuel doing this.

if the belt has slack in it the cam and crank timing will be out especially on light loads and feathering the throttle,again the computer will be working overtime.
this scenario can cause hesitations like that of the egr also.
think of belt in your hand with a bit of slack,then pull it apart fast and you could make it snap.theres the delay between cam and crank sync albeit small but it makes a difference.
good tension equals no delay.
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That's fair, but I never though that could influence the fuel economy in a large scale.
Any way, I guess that is more pronounced on engines with auto-tensioners, since with a manual tensioner, the tension will not change too much it's tension during its life time, as they don't tend to stretch or wear, at least if everything is ok B)

Daveybee said:
the f20b engine has the auto tensioner like the h22 found in the honda torneo sirt ;)
i have my ig timing set at 12btdc so its spot on.

im not great at explaining but maybe you understand B)
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Yeah, I get it :)
You checked that with a timing light?
Actually I have to check mine again. Checked it a while ago and it was ok. Will do that again to confirm if it's still ok.
 
checked with a timing light yes,theres a mark on the flywheel with tdc and 12'btdc.

cant think of any other reasons on poor fuel economy as most have been mentioned.
other than get a vacuum gauge hooked up and take readings too see what condition the engine is running.
B)
 
Do you know how many degrees it was off before changing the tensioner?

Never used the vacuum gauge, migth try thay aswell.
 
i had the timing advanced before i changed the tensioner.it was about 13-14 and now its at 12 as honda recommend.
ive checked it on the scan tool and its at 12 and drops to 11 occasionally.


vacuum gauge is a great invention,
this is a good readhttp://www.gregsengine.com/using-a-vacuum-gauge.html


i have my gauge built into the dash so its like a real time fuel efficiency meter aswell
 
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