I think I posted this in the wrong section. Here it is again.

Bought a 1995 GS 300 six months ago and am still trying to get to the bottom of its poor fuel consumption.

I'm getting 12.5 mpg (US) on local journeys. My normal journeys are anything between 3 and 12 miles. I don't sit in traffic with the engine running and I don't drive like a boy racer.

On longer journeys, even at high speeds, fuel consumption is twice that, which is OK.

When I start up from cold, I get a really strong smell of neat fuel from the exhaust. It's powerful enough to smell inside the car with the window down. I don't get the smell when the engine is at its normal operating temperature, but it's there if I start the car with engine warm.

I've already discussed this with Lexus UK, whose technical people were not able to suggest anything. The car has also spent a day with the local Lexus dealer, who said there was nothing wrong. But he didn't even bother to check the car when it was cold. I won't go back there again.

I've had two emissions checks on the exhaust which showed that emissions are OK. I reset the ECU, which seemed to improve the smoothness of the engine but didn't improve the consumption.

The car seems to idle, run, and perform normally.

Gasoline costs something like 6 dollars a gallon here and I'd really like to get this fixed some time soon. I intend to take the car to another Lexus dealer and don't want to be fobbed off again.

Any suggestions?

Stevie



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Hey, Stevie!

Your question is almost impossible to answer: there are just too many variables to consider that you haven't elaborated on.

Do you warm up your car or just turn the key and drive?

How fast do you drive on your short trips?

What gear do you spend most of your time in on your short journeys?

Hills, stop and go traffic?

How high do you rev the engine?

What kind of mileage do other people with comparable cars get on the same driving schedule as yours?

Have you changed the air filter + spark plugs?


I figure that to get a bad mileage (and I assume that this is abnormal figure for your car / driving style), the car has to burn more fuel: so you are either running too rich, or you are wasting some energy somewhere (like a slipping torque converter, for example). You know your driving style, so you can figure it out best.

Try to do some deductive work to try and isolate the conditions under which you experience poor mileage and then take it to a good mechanic. It may cost more to figure this out than to just pay for the gas, though.

 

Things to check:

1. Leaking fuel injector. Right after starting cold, check for black smoke in the tailpipe. Another symptom of a leaking injector is it takes longer to crank/start the engine as fuel pressure in the line has gone down as fuel leaked to the intake manifold. This is consistent with low mileage you're getting on short trips. Every time you stop the car, all that fuel pressure is dumped on the engine. On long trips, every drop of fuel is converted to energy therefore you get better petrol economy.

2. Oxygen sensor.
3. Water temp sensor.
4. The obvious which I'm sure you know about: tire pressure, air filter, intake connections like clamps are tight, no leak in vacuum system, etc.

good luck.
Let us know what solved it when it gets solved.

 

Thanks Vlad and Whitels for the pointers. I'm a little wiser now and will be calling the dealership next week to see if they can fix the problem. I know it's not my driving style. Nor is it tyre pressures, air filter etc. - I've checked all that.

I'll report back if and when they discover what's going on.

Stevie