Im not mech savvy but will try and phrase the question as well as I can.

What would be the affects of incorrect timing? Say after a timing belt change, it is out by a few degrees (I believe it is permissible, right?) would it affect:

1. A minuscule loss in power?
2. Would the above lead to increased fuel consumption?

After a major service recently on a TF auto sports, I want the car to be checked by the mechanic again to ensure it is all perfect as the fuel consumption has increased by about 2l/100km.

I did drop the tyre pressures from 36/34 to 32/30 to have a smoother ride but doubt if that is the cause?

Anything specific I should ask him to check?

Dropping tyre pressures will increase fuel consumption, not sure how much though mate

what makes you think its the timing? if you are talking about ignition timing, it is not possible for it to be out, unless something has really been stuffed by the mechanic. the spark is controlled by the ecu, not by the mechanical distributor. what exactly did you have done? depending on what tyres you have, i bet it is because you have let down the pressure in your tyres

As above, ignition timing is set by the CAS, ECU etc and is not adjustable. You can check it with a timing light to see if it is ok. Cam timing is slightly retarded by an old stretched belt, and a new one will bring it back to normal, and the car should run better if anything. Perhaps they changed the oil, and put something thick in it?

I can't comment on the timing part of it but I can defiantly tell you that your tyre pressure was to low to begin with so I cant understand why you would put less pressure in them. If you are having issues with your ride quality it is more likely to be because of suspension, shocks or bushes. Go and put 40 psi in your tyres and you will not only see a drop in your fuel consumption but your car will handle better and your tyres will wear more evenly and last longer.

Cheers Luke

the fuel consumption has increased by about 2l/100km.



That's normal. My TJ gets 10.5L/100 Km if I do long trips of 30 Km, with a lot of it at at 90 KPH. Short trips, of 3 to 5 km at 50-60 KPH gets 12.5 L/100 km. Long freeway trips get down to 9L/100 Km or less. I'm not blaming the last person who worked on my car for these variations. lol

what makes you think its the timing? if you are talking about ignition timing, it is not possible for it to be out, unless something has really been stuffed by the mechanic. the spark is controlled by the ecu, not by the mechanical distributor. what exactly did you have done? depending on what tyres you have, i bet it is because you have let down the pressure in your tyres

Yes I was thinking ignition timing.

I got a fair bit of work done, Timing belt, Hydraulic Tensioner, Idler Pulley, Water pump, all plugs (Platinum rear normal front), all leads, Transmission flush, Air Filter, Fuel filter, all gaskets, Throttle body clean, CV Boot needed replacing, drivers side engine mount needed replacing, Rear brakes.

Tyres are the Bridgestone Turanzas 215/60/16



As above, ignition timing is set by the CAS, ECU etc and is not adjustable. You can check it with a timing light to see if it is ok. Cam timing is slightly retarded by an old stretched belt, and a new one will bring it back to normal, and the car should run better if anything. Perhaps they changed the oil, and put something thick in it?

Brand new belt. Will get them to check it again.

Yes the car is a lot smoother but I felt loss in power and consumption has certainly increased.

I doubt if it is the oil



I can't comment on the timing part of it but I can defiantly tell you that your tyre pressure was to low to begin with so I cant understand why you would put less pressure in them. If you are having issues with your ride quality it is more likely to be because of suspension, shocks or bushes. Go and put 40 psi in your tyres and you will not only see a drop in your fuel consumption but your car will handle better and your tyres will wear more evenly and last longer.
Cheers Luke

Front shocks were changed about 50k before.

Will try 40 PSI but from memory the ride is bumpy



That's normal. My TJ gets 10.5L/100 Km if I do long trips of 30 Km, with a lot of it at at 90 KPH. Short trips, of 3 to 5 km at 50-60 KPH gets 12.5 L/100 km. Long freeway trips get down to 9L/100 Km or less. I'm not blaming the last person who worked on my car for these variations. lol

The travel pattern has not varied but the consumption has since it came back from the service. Hence I thought I would post up and find out if there is anything obvious which you want me to have looked. Something that might have been worked on during a major service and in error not put back as supposed to?

From memory I recall reading about vacuum hoses and it causing bad consumption figures. Again not being mech savvy, thought I would ask here first and take the info back and get the mechanic to go over the car again.

I know the mechanic for a long time and know his work but if he has let any of his apprentices to work on the car and they have stuffed it up, I do not know :(

Unless you have something specific to complain about, the mechanic can't really do anything. Sounds like you don't really trust the mechanic or his apprentices. Why not read the manual and work out how to do things yourself?

All of the stuff you mentioned: "Timing belt, Hydraulic Tensioner, Idler Pulley, Water pump, all plugs (Platinum rear normal front), all leads, Transmission flush, Air Filter, Fuel filter, all gaskets, Throttle body clean, CV Boot needed replacing, drivers side engine mount needed replacing, Rear brakes" can be done by a home mechanic, after a few years of hands on effort.

If you do stuff yourself you can save heaps of money and avoid that feeling of "there's something not quite right".

That kinda change in tyre pressures would not affetc fuel cons THAT much, no way. Perhaps some 1/10's - not liters.
40PSI? Hmmmm, not for those tyres. Too hard. But try if you wish.
Oil? Doubt it, unless it's something really thick stuff aka shite.
Those repairs done, should not damage the cons, on the contrary. Wonder what kinda airfilter there is, some cheapo paper stuff. Get K/N.

That kinda change in tyre pressures would not affetc fuel cons THAT much, no way. Perhaps some 1/10's - not liters.
40PSI? Hmmmm, not for those tyres. Too hard. But try if you wish.


Agree, thats bit too much for those tyres, i run 40psi but on 235/45. Really i did not notcie any fuel dif whatsoever when i swapped from stock wheels 15s running 32 psi to 40PSI 17 inch. If there was a diff it would be too minor.

Really to increase your fuel by 2llitres per 100 it has to be something a lot more serious, my first suspect would be O2 sensor, get it tested to see if its getting lazy. From your list i can see you did not change it, you really should replace one every 120,000ks.

Things like oil, air filter would seriously not make any noticeable difference. I have gone from paper to KN without any difference in fuel consumption. At one stage i also used Penrite 0-60, again no dif whatsoever.

2L/100kms off a couple of psi - unlikely.

Is your idle etc any rougher? Quite easy to slip out a tooth during tensioning. I'd definately look into it, somethings not right.

2L/100kms off a couple of psi - unlikely.

Is your idle etc any rougher? Quite easy to slip out a tooth during tensioning. I'd definately look into it, somethings not right.

Not really

Could be due to the E10!

See below the consumption over the last few fills

Km Travelled Litres Used Average Comments

610 67.57 11.08L/100km Shell 95 unleaded
552 60.76 11.01L/100km Caltex 95 unleaded
553.4 63 11.38L/100km Wollies unleaded 36/34 pressure
500.6 67.96 13.58L/100km Wollies unleaded
501.3 62.25 12.42L/100km Wollied E10 – Major Service
439.9 52.79 12.00L/100km Shell unleaded 32/30 pressure
518.5 60.89 11.75L/100km Shell E10
466.6 64.65 13.86L/100km Wollies unleaded

Last fill has been with Shell 95 and can already see many more km to the quarter tank mark.

Hard to justify the price diff for a fill between E10 and 95 now.

Driving pattern has not changed much. Mix of traffic and motorway driving.

I will get the car checked out anyway.

I dont see how you can blame the E10, seeing as you did better on Woolies E10 than you did on regular, and the same with Shell.

Looking at your records you probably just had a bad week. The two tanks after the major service were lower than the one before, even after you lowered the tyre pressure. You probably just had a bad week.

You do use more E10, its a fact, also more ethanol higher consumption is, like for example E85 will increase your consumption about 15-20%. Science behind it is quite simple, although its higher octane that normal petrol it has less energy per equivalent volume as petrol does, so you obviously have to burn more of it in order to release same amount of energy as normal pertol

You do use more E10, its a fact, also more ethanol higher consumption is, like for example E85 will increase your consumption about 15-20%. Science behind it is quite simple, although its higher octane that normal petrol it has less energy per equivalent volume as petrol does, so you obviously have to burn more of it in order to release same amount of energy as normal pertol

And even after filling with higher Octane petrol after a E10 tank, it does not fully come back to normal consumption straight away is what I have noticed. Car is noticeably rough (to me) in low RPM on E10 as well.

Will monitor this and see how things go.

Thanks for the replies guys

That's dead right andrei.

The thinking is that e10 is cheaper than e0 (pure unleaded), and supposedly the difference in consumption is offset by the cheapness.

That's dead right andrei.

The thinking is that e10 is cheaper than e0 (pure unleaded), and supposedly the difference in consumption is offset by the cheapness.

Agree but from my last fill (From memory) the Shell E10 was $1.49 and Unleaded 95 was $1.69. How can one justify such a price gap as the consumption won't be as good!

Was E10 at one stage not only 4c lower than unleaded?

We need to come up with right terminology too some say that unleaded has now been banned?

Are the options left now E10, Unleaded 95 & Premium Unleaded 98?

You do use more E10, its a fact, also more ethanol higher consumption is, like for example E85 will increase your consumption about 15-20%. Science behind it is quite simple, although its higher octane that normal petrol it has less energy per equivalent volume as petrol does, so you obviously have to burn more of it in order to release same amount of energy as normal pertol

I am aware of this... That wasn't my point, I was trying to make it noticed that his fuel consumption has been all over the place and doesn't seem to relate to his fuel type or tyre pressure, and that he probably just had a bad week this week with traffic or whatever, to make such a big difference.



We need to come up with right terminology too some say that unleaded has now been banned?

Are the options left now E10, Unleaded 95 & Premium Unleaded 98?

No, regular unleaded hasn't been banned. 7-Eleven, surviving Mobils and possibly Caltex still sell regular 91, usually it's 2c/L more than E10.

I'm all for using ethanol, in fact as I see it it's the easiest way of using current infrastructure to solve future (possibly quite near future) oil problems. Something like GM sugarcane crops in the middle of nowhere, grown with chemical aids (contained of course, ie: no possibility of aquifer poisoning) just to get the crops growing, is one of the great possible solutions to BOTH depleting oil supplies and climate change. We can even use the same cars with a tune (and possibly a fuel filter change).

But as a consumer the extra consumption doesn't offset the price unfortunately. It's extremely difficult to calculate though as the ron, and hence composition, of e10 varies dramatically between companies.

A lot of E10 sold now, particularly in Qld & NSW, is 91 RON - the same as ULP. So far I'm not having any trouble getting Shell 94 RON E10 here in the ACT. It was 3c/l cheaper than ULP, but in the last month or so the gap has been reduced to 1.5c/l (same for Caltex in this area).

You will generally use 3.5-4% more E10 than ULP for a given tune; doesn't sound like much, but its 0.4l/100km on top of 10l/100km.

I'll give you the hot tip - i only buy petrol from BP if not available then shell then caltex.

I never buy from woolies etc franchises. Check to see if your next tank is fine.

....Woolworths is Caltex. The trucks go to both Caltex and Woolworths, and it's the same thing with Coles Express/Shell. :confused:

Hmmm, tuned mine for 98 - nowadays mainly Ultimate - for a reason. Goes ok and consumption very reasonable.
But as many other comments, bad week and/or crappy fuel might have well been the reason, if nothing else is found wrong.

Finally found some time to drop this off today and I got it back.

Timing was fine, computer came up with no faults or error codes. He still changed a couple of pipes which were on way out which should have been changed at the last service!

It could be a bad batch of fuel as the last tank on Shell Unleaded gave me:

Km Travelled Litres Used Average Comments
549.3 66.05 12.10L/100km Shell Unleaded

What I was hearing though was exhaust on its way out.

Once up on the hoist it was easy to locate that there is a leak just behind the muffler, right on top of the pipe. As soon as it is plugged with the finger, the sound drops. There is also another leak in the middle portion, a long fine one. So I guess, I will be looking at options for changing the 2sections behind the cat.

Any suggestions guys?

Please note that I do not need any performance gains or aural delights.

Original one is fine as well.

I know you not after performance, but might as well get red back exhaust, its about $350 from Ebay, im guessing replacing stock one would cost something similar anyhow so think about it......