Engine Labouring As Too High A Gear Selected

[steveledzep]

Hello everyone.

Had my IS250 SE-L since November last year and I'm very pleased with it.

However, I'm increasingly experiencing a problem. When I return from work, I have to turn right into a lane with quite a steep uphill gradient. I'm quite gentle on the accelerator at all times, but I have to "boot" it on this hill otherwise I get vibration from the engine labouring. It's not just a gentle increase in throttle pressure required, but quite heavy, otherwise it won't change down a gear.

More recently, I've noticed similar vibration/labouring on flat roads with 30mph speed limit. It's as if the car is trying to operate in too high a gear at about 1100rpm. I'm all for changing up rapidly to get maximum return on fuel consumption, but what I'm experiencing seems excessive as I don't believe I should experience vibration and labouring. A blip on the throttle gets it to change down, but I think the car should "automatically" select the correct gear ratio to avoid labouring the engine.

Can anyone throw any light on this please ?

Steve.

[steve2006]

Modern cars of any make these days tend to have to learn the way the car is driven. It may be worth disconnecting the Battery for a short while to allow the ECUs to reset and then relearn, just make sure any radio or other security codes are available just in case.

[steveledzep]

Thank you Steve. I had read about that elsewhere, but was unsure about doing it, seeking reassurance on here I suppose.

I'll certainly try that, but will wait awhile in case another member comes up with an alternative solution/diagnosis.

[Jamesf1]

At 30 mph mine is in 5th @ around 1100 rpm, with no problems like you describe. I'm wondering if the labouring could be down to the common sticking brake caliper issue...

[steveledzep]

That's a good shout James, but I had the brakes seen to when I bought the car last November.

There was one sticking caliper and one siezed. I replaced the siezed one and had all of them lubricated, so unlikely to be the cause after such a short period of time.

Unless you know different of course ?

[steveledzep]

If I adopt Steve's solution and disconnect the Battery for a while (overnight ?). Will I lose other settings than the radio code ? Seat memory positions ? Will the electric windows work correctly and everything else electric for that matter ?

I'm very nervous of a "re-set" of the ECU in case there are other consequences ?

[JamesG]

I have a similar problem with my autobox trying to use a higher ratio when I get to a steep hill and don't have a run up. I suppose this is it's attempt at fuel saving. What I tend to do is just put it into sport before the hill and it automatically gears down to 4th so I don't have to pump the gas to get to change down for the hill then I change back to D once I'm over the crest.

I also have an small issue going downhills, on my travels I go down a sweepish slighty twisty lane, I go into the downhill at about 40mph and then don't need to accelerate until the bottom, which was quite fun in my '200 manual for the twisty bits. The '250 is a bit more scary, when I'm braking from 60 to 40, to go down the hill, the box gears down to 4th or so, for engine braking. This is fine, but I like to free wheel down the lane, and in a small dip the '200 would make it through without more gas, but I find I need to touch the gas on the '250, to get it over the rise, then the gearbox thinks its time to change up a gear and this in turn causes a burst of acceleration which I then have to brake for which can be a bit frighting.

Anyway I think it is the gearbox trying to be too fuel efficient, drop it into sport occasionally, it gives me a more of a feeling of actually being in control.

J.

[JamesG]

30mins should be fine to reset the ECU by disconnecting the Battery. The only thing to worry about is the auto windows. They won't work from the doors straight away, you need to open and close each one fully from the drivers door, then they should be fine. And any memory like radio, seats, steering and mirrors will need resetting, although I don't remember doing the seats after the last Battery change...

J.

[steveledzep]

I suppose this is it's attempt at fuel saving. What I tend to do is just put it into sport before the hill and it automatically gears down to 4th so I don't have to pump the gas to get to change down for the hill then I change back to D once I'm over the crest.

Anyway I think it is the gearbox trying to be too fuel efficient, drop it into sport occasionally, it gives me a more of a feeling of actually being in control.

Thanks James.

The gearbox is described as "automatic" so I don't expect to have to manually compensate. If conditions dictate a change-down, then I expect it to happen. I've had Saabs before and didn't experience this problem.

I'm all in favour of high gears to save fuel, I don't go tear-arsing any more, but do expect the correct gear for the conditions.

I'm off work on Friday, so will try disconnecting the Battery. I'll report my results.

There isn't a lot wrong as I've been to North Wales and back today (c300 miles) and averaged 35.3 mpg....not speeding, but driving with progress in mind !

[normski2]

If I adopt Steve's solution and disconnect the battery for a while (overnight ?). Will I lose other settings than the radio code ? Seat memory positions ? Will the electric windows work correctly and everything else electric for that matter ?

I'm very nervous of a "re-set" of the ECU in case there are other consequences ?

To reset your windows take a read here

http://www.lexusownersclub.co.uk/forum/tutorials/article/200-initializing-windows-after-battery-change/

[johnatg]

Try using the ECT switch 'Power' setting. My observation is that this makes general progress slightly less smooth, but the car is more likely to be in the 'correct' gear at any given time, especially where you have to slow down for sharp bends or climb steep hills. It also seems to give you a bit more engine braking when descending hills.

There does not seem to be any fuel consumption downside.

[lexusisfan]

Hi Steve,

I haven't experienced your particular scenario, but sometimes I feel that the gearbox changes gears up and down either too earlier of late.

I've now been using the ECT power mode and I feel the gearbox much more responsive.

[Derek870]

I agree with using the ECT mode, I think the Lexus way is high gear,low revs and quiet, but as you notice it stays in high gear too long

I leave my ECT on permanently, economy hasn't changed and I feel the car is in the 'right' gear and more responsive when required

[steveledzep]

Thank you for your responses gentlemen.

It's interesting that having ECT permanently on is a recurring suggestion. I'm surprised that you are reporting little, if any, detrimental effect on mpg ! I'll give it a try and monitor mpg at the same time.

I used ECT on the way home from work this evening, I was disappointed that it laboured up the hill in my lane.

Maybe I need to change my driving style to suit the car ?

I'll try disconnecting the Battery for a while on my day off on Friday.

[is200 Newbie]

I would try the obvious

Is the air filter clean?

Re-check the calipers - front and back - it will rule them out as holding the car back which it sounds like a probable cause

Is the handbrake on?

Is the exhaust blowing?

Reset the ECU - not hard to do and you wont lose any vital info - clock / windows / seat memory settings / I think you will need to re-tune the radio in if leaving the Battery disconnected overnight. Its nothing that cant be set back. Remember, after resetting it, drive the car as you would normally do until it learns the driving style.

Let us know how you get on .....

[Jamesf1]

I was going to suggest driving style before you try the Battery. Just a bit more gas. Worth a try....

Another thought, what fuel do you use? I've run almost exclusively on Shell v power and find the engine smooth an pulls ok from low revs.

[steveledzep]

Hi James. I am a bit of a wimp on the throttle ordinarily. Yesterday though, I had to make good progress to North Wales and back, 300 miles round trip.

The car performed very well, on winding, hilly, single carriageway roads for the most part. I passed loads of lorries and tractors and returned 35.3 mpg (car computer).

I alternate between Asda fill up and Texaco fill up, never letting it get below 1/4 full. I live in the sticks, can't recall seeing a Shell service station !!

Car had a full (60,000) service just 3000 miles ago, so air filter should be spotless, parking brake not on and calipers sorted as described.

I'm looking forward to giving the computer an opportunity to learn my driving style. It has 68,000 on the clock and I've only done 3k of them.

I'll be reporting back on all my experiments. Thank you all for your interest and participation.

[ChumpusRex]

The IS, like many other 4 valve per cylinder normally aspirated cars, likes revs.

I find I need to get the revs up above 4000 before the engine stops daydreaming and decides to do something.

The car really benefits from having the transmission in power mode.

[normski2]

I have my car permanently in ECT/PWR mode.

Tried in both modes with virtually no apparent mpg difference.

I find the car responds nicely in this mode.

[johnatg]

I would forget the ASDA fillups - use Texaco Supreme (the more expensive one) all the time. I know you're right about there being few Shell stations in Carmarthenshire (or S Wales generally). I use Shell V-Power all the time - Texaco Supreme is nearly as good. It is 97 octane rather than 98 but has good cleansing additives.

An aside: We went on hol near St Davids last year in my supercharged MX-5. It needs Shell V-Power - or at least 98 octane fuel or it pinks (detonates) like crazy. It's a very practical car - it has a very small boot and I have to navigate via Shell stations. As it is also water-injected (substitute for intercooling) - and it injects 2/3 distilled water and 1/3 methanol - it needs copious supplies of both. Hell of a lot of fun, though - it has about the same power as the Lexus and weighs not much more than half as much!

Anyway, I located the Shell staions on route and identified one (of the few) in Llandysul - went about twenty miles 'off-route' to get to it and found it didn't sell V-Power! I ended up using Texaco Supreme + Octane booster, which I carry for such occasions (rather frequent in the sticks!)

You don't need to go to such extremes in the Lexus, but it's well worth using the most expensive fuel.

And don't be afraid of the accelerator pedal! The car will soon change down if it knows you actually want to get up the hill!

[normski2]

Car had a full (60,000) service just 3000 miles ago, so air filter should be spotless, parking brake not on and calipers sorted as described.

Mmmm I wouldn't put too much hope on that.

I was told they 'inspect' the air filter at regular intervals.....but only change every 40,000 miles. Staggering is it not.

Just had my 60K service done and its the same filter in there. So yours is likely to have done 23K to date.

Don't be surprised to find yours is filthy in there.

I get my own filters and do them myself.

Air filter every 15000 or visual check.

Cabin/Pollen filter every 12 months or so.

Have two on order right now. Less than £20 delivered.

[dave1]

The IS engine is nothing special that really requires 98 octane fuel. Lexus dealers don't put it in and Lexus don't tell you to use it. Standard unleaded is fine for them.

In 13 years of Lexus ownership I have never felt the need to use higher octane fuel and the same for Hyundai, Honda and Mitsubishi power units.

[johnatg]

It's not really the octane rating but the fuel system cleaning properties and smooth burn features of some of the expensive fuels that are the real advantages. But the octane rating does help - all modern engines are optimised for 97 RON fuel - the fact that they run OK on 95 is because no manufacturer wants to be seen insisting on 97.

(I suppose the smooth burn is attributable partly to the octane rating, but some fuels are better than others.)

IMHO

There is a bit of anecdotal evidence on this forum that the small increase in cost is largely offset by similar small improvements in fuel economy.

[steveledzep]

Thank you all for your contributions. There are so many things for me to try !

I am confident that the calipers are free and the park brake is off and I don't have an exhaust problem. However, Normski's post about the air filter surprised me, I'll check it out.

Hopefully, I can approach this in a methodical manner. The potential solution that most interests me is the resetting of the ECU and allowing it to learn my driving style. I want to evaluate that approach first.

I find it very interesting to hear many recommendations for running permanently in ECT/POWER mode. I can try that next, but will be monitoring fuel consumption closely !

I really don't see me going down the route of higher octane fuel, Dave1 summarises my viewpoint on that. However, I shall keep with premium brands and avoid the supermarket fuel. Is it really lower quality, or is it their buying power that allow them to sell 3 or 4 pence per litre cheaper ?

I'll let you all know my findings.

[dave1]

Having used mix of Morrison's, Asda & Tesco fuel for as long as it has been about in various cars including Lexus GS300 for 6 years (60k + miles) GS430 for 7 years ( only 26k miles), Rover827Si, Audi 100, Hyundai i30 to mention but a few I can see no reason not to use their fuel. To date none of my cars or wife's cars have had any fuel related issues and have given excellent fuel consumption. I do, however, respect that some people do not trust "supermarket fuel" and don't use it - which is their prerogative.