Mpg Questions

[revs]

Hi Guys,

Been a long time lurker on the forums, after having ready many threads and posts I bought a 97 R reg LS400 about a year ago.

Was very happy with the car until I got a it serviced by an independent garage a few months ago.

I'd like to start off by asking what you guys are getitng fuel wise locally.

I'm getting 40 miles and no more for each £25 fill, this is only local and no heavy footed driving, is this excessive or normal?

Any input would be greatly appreciated.

[Parthiban]

I have no experience of the LS400 but that works out to 9.4mpg which does sound poor - what sort of mileage were you getting beforehand?

[SteveLS400]

Hi Guys,

Been a long time lurker on the forums, after having ready many threads and posts I bought a 97 R reg LS400 about a year ago.

Was very happy with the car until I got a it serviced by an independent garage a few months ago.

I'd like to start off by asking what you guys are getitng fuel wise locally.

I'm getting 40 miles and no more for each £25 fill, this is only local and no heavy footed driving, is this excessive or normal?

Any input would be greatly appreciated.

It's rubbish. At £1.29/litre thats £5.86/gall so £25 is 4.27 gal which should give you over 100 miles..

I checked mine last week - 28.6 mpg. Your're getting about 9.6 mpg - about a third of what you should get.

The only way to check is to fill up and note the mileage and fill up again.

[sir john]

I agree with Steve. £25 at present prices is about 4.27 gallons.

I use my car for client to client driving so not exactly hanging about: i am getting about 23 to 24mpg.

On a long motorway run and easy relaxed driving i get 26-30mpg.

if your figures are correct, there is something seriously wrong. I cannot imagine it would run right at 9mpg.

Q 1: can you smell petrol from the exhaust on start up from cold?

Q 2: does it run smoothly?

Q 3: are there any other symptoms of over fueling of running rich?

Do a brim to brim. Brim the tank/zero the "trip A" on the dashboard . Run until almost empty and refill.

Divide the number of litres of fuel by 4.55 to give you the gallons used.

Then divide the miles on Trip A mileage.

EG: 62.3 Lt div by 4.55 = 13.69 gallons.

426 miles traveled since last filled up divided by 13.69 = 31.12 mpg.

let us know how you get on. We will help you all we can.

[mike213735]

I have a '98 MKIV and have been paying close attention to MPG of late.

On a recent run to Gatwick (I live in reading) I averaged 35.2mpg which I was very happy with.

In town, stuck in Reading traffic for about 20mins to travel 3 miles, I get about 17-19mpg, which means your £25 at Readings £1.339, should do me about 70miles. I don't think that's bad for a 4.0 litre top end car either.

I agree with sir john, brim to brim is the only way to be sure!!!

Thanks

Mike

[SteveLS400]

Just check you havent got a leak in the tank or fuel line area before you fill up. A visual inspection is all thats required. Once we know the exact mpg, I have no doubt help will be forthcoming.

[Malc]

Hi, not heavy footed and about town I achieve early 20's mpg and on a good run, fully loaded and averaging 75mph it achieves 30 mpg on a good day.

Heavy footed and it seems as though I'm pumping the fuel straight out of the tank !

Malc

[revs]

Hi Guys,

Many thanks for the replies.

The computer suggests 11.7-12.5mpg

The MPG is the least of my worries because after the service, these are the things i've encountered:

1. From a cold start the choke is on for at least 10 minutes.

.

2. Excessive smoke, not blue smoke just the condensation type, it's there almost all the time unless the outside temperature has risen.

3. The idle is not as quiet as before, it sounds as if the choke is on at idle tickover RPM's.

4. There is a drone like noise from behind the front passenger wing.

5. After only a couple of week the service, the mechanic checked the spark plugs and they were pinkish, the car passed the MOT perfectly though.

The car runs smooth, there is no loss in power or water coolant, the temperature etc is normal.

The car has done 105,000miles with FSH if that helps.

I loved the car when I first got, but now I honestly don't even feel like driving the car, the lexus silcenc isn't there anymore:(

[revs]

Oops double post. Sorry.

[Malc]

Sounds like a crappy service to me !

These cars are just about bullet proof. I've been driving the LS 400 for 8 years or so as my main car ( second LS now ) and have done about 100,000 effortless miles in that time.

Few service costs but ZERO grief.

Suggest you get someone competent to give it another look.

Malc

[Mybikesacx500]

You need a mechanic that can check the OBDC codes, sounds like the engine temp sensor or air flow meter or such is not working, and you are possibly in "limp home" mode, any dash warning lights?

Hi Guys,

Been a long time lurker on the forums, after having ready many threads and posts I bought a 97 R reg LS400 about a year ago.

Was very happy with the car until I got a it serviced by an independent garage a few months ago.

I'd like to start off by asking what you guys are getitng fuel wise locally.

I'm getting 40 miles and no more for each £25 fill, this is only local and no heavy footed driving, is this excessive or normal?

Any input would be greatly appreciated.

[sir john]

Hi Guys,

Many thanks for the replies.

The computer suggests 11.7-12.5mpg

The MPG is the least of my worries because after the service, these are the things i've encountered:

1. From a cold start the choke is on for at least 10 minutes.

.

2. Excessive smoke, not blue smoke just the condensation type, it's there almost all the time unless the outside temperature has risen.

3. The idle is not as quiet as before, it sounds as if the choke is on at idle tickover RPM's.

4. There is a drone like noise from behind the front passenger wing.

5. After only a couple of week the service, the mechanic checked the spark plugs and they were pinkish, the car passed the MOT perfectly though.

The car runs smooth, there is no loss in power or water coolant, the temperature etc is normal.

The car has done 105,000miles with FSH if that helps.

I loved the car when I first got, but now I honestly don't even feel like driving the car, the lexus silcenc isn't there anymore:(

Definately something wrong here. 11-12 mpg is not right.

Dealingf with your points one by one (bear in mind my LS is a 93 model,but should be the same as yours in principle)

1: mine is fully up to temp in about 5 minutes but its off choke quicker.

2: mines a bit like yours at the moment. I think its more to do with air temp and damp air in general.

3: this isnt right. you should not be able to hear theh car at tickover, inside the car or out unless you have an exhaust blow.

4: again not right. 1st guess:exhaust.

5: pinkish spark plugs usually means the mixture is too lean. I checked mine last month, after 20k miles, they were clean.

I agree with Malc and CX500. Get the car serviced properly and start enjoying your LS again.

In the mean time do a couple of quick checks;

1; check the exhaust isnt blowing.

2: take the air filter. It could be stuffed up with leaves.

Good luck mate. It pains me when someone isnt enjoying their LS because i so much enjoy driving mine.

[revs]

You need a mechanic that can check the OBDC codes, sounds like the engine temp sensor or air flow meter or such is not working, and you are possibly in "limp home" mode, any dash warning lights?

Hi Mybikesacx500

There are no dash warning lights this what puzzles me.

Do you or anybody else of of any decent mechanic with OBDC for Lexus in leeds or west yorkshire?

[revs]

Definately something wrong here. 11-12 mpg is not right.

Dealingf with your points one by one (bear in mind my LS is a 93 model,but should be the same as yours in principle)

1: mine is fully up to temp in about 5 minutes but its off choke quicker.

2: mines a bit like yours at the moment. I think its more to do with air temp and damp air in general.

3: this isnt right. you should not be able to hear theh car at tickover, inside the car or out unless you have an exhaust blow.

4: again not right. 1st guess:exhaust.

5: pinkish spark plugs usually means the mixture is too lean. I checked mine last month, after 20k miles, they were clean.

Hi John,

1. Therein could be the fuel due a faulty thermostat?

3. I've not heard any exhaust blow. The loudness is more from the engine tickover as if the choke is on when it is not.

[M.IQBAL]

hi

Just wanted to add that after recently aquiring a mark 4 i had the same problem. I noticed the fuel guage was going down quicker then my mark 3 and the readout was only achieving 13mpg at best. I changed the ECT sensor and now i get between 19-22mpg. I do mainly town driving.

I would recommend checking the above sensor.

have a read here: http://www.clublexus.com/forums/ls400/376713-all-ls400-owners-with-bad-gas-mileage-read-this.html

it also tells you how to test the sensor prior to replacement

regards

miq

[Mybikesacx500]

I'm up in Glasgow, but you don't need a specific Lexus mechanic, the obdc stuff is suposedly generic. Try the local lexus or Toyota dealers for a quote, my local Lexus dealer is quite good for quotes, they even washed my old '92 for me, when it was fairly obvious they wer'nt going to get the work.

You need a mechanic that can check the OBDC codes, sounds like the engine temp sensor or air flow meter or such is not working, and you are possibly in "limp home" mode, any dash warning lights?

Hi Mybikesacx500

There are no dash warning lights this what puzzles me.

Do you or anybody else of of any decent mechanic with OBDC for Lexus in leeds or west yorkshire?

[Mybikesacx500]

The engine temp sensor (the one with 2 connectors) is another possibility, if its telling the car its below freezing, for instance. it won't show as a fault.

Is it reluctant to start from hot?

hi

Just wanted to add that after recently aquiring a mark 4 i had the same problem. I noticed the fuel guage was going down quicker then my mark 3 and the readout was only achieving 13mpg at best. I changed the ECT sensor and now i get between 19-22mpg. I do mainly town driving.

I would recommend checking the above sensor.

have a read here: http://www.clublexus...-read-this.html

it also tells you how to test the sensor prior to replacement

regards

miq

[revs]

Is it reluctant to start from hot?

It's fine starting from hot.