albrusgher

Hi, everyone
My Lexus GS450 h has now 274 thousand kilometers, and the fuel consumption has been always very low.
A couple of months ago I changed the 6 spark plugs at an official dealership and since then, the car, with the same type of driving (super quiet) began to consumpt about 2 liters more per 100 km.
During the spark plug replacement process, the dealership had problems with one of the engine spark plugs and they needed many hours to be able to remove it....
I've already made some changes: such as the flow rate and the intake regulator and things have improved, but not completely ....
Any idea to help? (The spark plugs are exactly the same than the previous one).

gripau1

I would take it back to the dealer, talk to them about your findings and concerns and let them have a look at it. They should be scanning with Techstream for any error codes etc.

Fuel consumption could be any number of things even the weather and type of fuel you use. We have been having very cold mornings and I notice the hybrid system doesn't go on as quickly until the water termp goes up to normal. I'm usually getting about 6.2litres/100km but recently in cold winter mornings about 6.7litres/100km fuel consumption.

bclexus

Replacing the spark plugs was not needed because they'll last more than twice that mileage you currently have with no change in performance or fuel economy.

Replacing them with the exact same spark plug brand and part number should not affect fuel consumption or performance at all - for better or worse.

Hope they are not counterfeit or fake spark plugs or one plug did not have stripped threading...

albrusgher

[QUOTE=albrusgher;11744083]Hi, everyone
My Lexus GS450 h has now 274 thousand kilometers, and the fuel consumption has been always very low.
A couple of months ago I changed the 6 spark plugs at an official dealership and since then, the car, with the same type of driving (super quiet) began to consumpt about 2 liters more per 100 km.
During the spark plug replacement process, the dealership had problems with one of the engine spark plugs and they needed many hours to be able to remove it....
I've already made some changes: such as the flow rate and the intake regulator and things have improved, but not completely ....
Any idea to help? (The spark plugs are exactly the same than the previous one).I have already taken the car to the same dealership where I changed the spark plugs on at least two occasions. They tested it on the official checking machine and the results were always the same: everything OK.

albrusgher

It was then when I decided to change the two mentioned components. After this change the consumption returned almost to the previous one, but it is still somewhat high... I am hesitating whether to check the compression of all 6 cylinders. The fuel, the outside temperature, and the driving style have always been very similar, hence my surprise at the sharp increase in consumption...

gripau1

If there are no errors detected from the OBD then its outside variables such as fuel quality, temperature driving style, tyre pressures, when was the diff and transmission last serviced? Could be as simple as one of the brake calipers stuck?

If you have a low compression in one or more cylinders you will know it straight away. The engine will shake because its running on 5 cylinders, and most likely a CEL will pop up.

Remember similar condition is not exactly the same as repeatable lab conditions. Small changes in consumption is expected to be normal.

Things that deteriorate overtime and mileage and considered wear items such as the likes of catalytic converters, oxygen sensors, coils, partly blocked fuel injectors, carbon build up, TPMS, air filters, fuel filter, fuel pump, MAF sensor, PVC and EGR even the oil you use all contribute one way or another to small increases of fuel consumption if they are not in tip top condition.

If you are still worried, then try unplugging the 12v battery which hopefully resets the long term fuel trims and resets the adaptive learning in the TCM and ECU. Drive and and monitor and do an Italian tune up once in awhile.

gripau1

I have a Jaguar XKR as a weekend toy. If I drive like a granny I get about 11litres/100km. If I drive spiritedly the car can be consuming easy 20litres/100km. At $2.50 per litre for fuel yeah its expensive but I don't drive it everyday that's what the GS450h is for. The Jaguar XKR its smiles per miles as they say and its in great condition. The fuel consumption on the XKR varies tremendously.