Ls400 94' Idling

[2ard]

This is regarding the idle speed on the car when idle or when in drive with the brakes on. My car is sitting on 600 RPM when it's warmed up. Please can those of you who have LS400z let us know what your vehicle idle @ !! Many thanks in advance for your replies ladies & gent !

[Paulrwales]

Ours seems to stay at ~600 rpm without the a/c on when warm

[2ard]

Cheers for quick reply there Paul. Lexus recons they should be @750. I've reved mine up to 750 but it doesn't sound right. It sounds too loud !

Anyway, interested to see other people's experience on this ...

[GreyBeard]

This is regarding the idle speed on the car when idle or when in drive with the brakes on. My car is sitting on 600 RPM when it's warmed up. Please can those of you who have LS400z let us know what your vehicle idle @ !! Many thanks in advance for your replies ladies & gent !

mines a 1990 LS400 and it ticks over in drive, when warmed up, at 750 but it has just been serviced. on cold starts its 1400 or so.

[ColinBarber]

I think the idle on the 4.0V8 is 700 +- 50. 750 for the 4.3. All figures are without the AC on

Remember that your rev counters is only a guide and could be 200rpm out so shouldn't be used for checking idle speed.

[flotsam]

I've reved mine up to 750 but it doesn't sound right. It sounds too loud !

I take it that's with the bonnet up and your ear to the engine. I can't hear mine at all when driving. As the first automatic I've owned, I used to change gear at junctions and then wonder why nothing was happening when I put my foot down.

[maneesh]

My 1992 model idles at 600rpm with brake depressed in D when warmed up, always has for the past 6 years.

[ColinBarber]

Idle should always be checked at full engine temp. in Park, no AC or any electrical devices running.

[2ard]

Colin => It makes no difference in my case still get idling @ 600

[ColinBarber]

Colin => It makes no difference in my case still get idling @ 600

How are you measuring the rpm, using the rev counter on the dash or an external device?

Your throttle body may need cleaning if the idle is too low.

[2ard]

I tried using carb cleaner from Halfords, but that really didn't do anything. I had it taken to a garage, not Lexus though, and they were telling me that there are gaskets that will need replacing if they were to take the whole throttle body out (which is what they recommend is needed). I was informed that there are 2 gaskets however calling lexus parts, they were saying there is only 1. I have a series 1 94 model, so Im a little confused really. The trottle body instructions are okay, but the stuff I used just didn't do the trick. There is such a solid carbon deposit behind the butterfly valves that I think Im goning to need to use Sulphuric acid or something (joking ofcourse !).

[risingsun]

mines a 1990 LS400 and it ticks over in drive, when warmed up, at 750 but it has just been serviced. on cold starts its 1400 or so

Greybeard If your car "idles" at 1400rpm before warming up, don't you get a major clunk when you engage Drive - as well as a jolt - as the gearbox is engaged at such a relatively high engine speed?

I only ask because my car idles at the same speed when cold - and I get both of those!

Anybody else here suffer from high idle speed when cold? Any solutions out there?

All contributions welcome. Thank you.

[ColinBarber]

It's meant to idle at that speed. It should quickly start to come down as the engine warms.

Clunks and jolts when engaging drive indicate more of a problem with the auto box.

[2ard]

My 94 LS400 idles @ 1200 when cold, but I don't get jolts when moving off after firing her up ! :mat:

[risingsun]

Thanks guys. That's interesting. (It seems you don't have to get a jolt even when the revs are high. That's news to me, right there.)

Well, if there is actually something wrong with the gearbox to cause this lack of smoothness (when engaging Drive at those kind of revs) does anyone have any idea what it might be?

I've already taken the car to be examined by my local dealer (in Cardiff) and discussed the whole issue with them. They found nothing wrong. Amazingly, however, I got the distinct impression from talking to the service managers that they weren't terribly clued-up about the actual transmission units in these cars. They claimed they'd never had a problem with one before and, hence, they had no real problem-solving experience to call upon.

Maybe I should take it to a transmission specialist instead. Guess what? I already did that, too, and with the same result. (No problem found.)

Help!!! (This cold start jolting is slowly driving me nuts!) Otherwise the car is brilliant and it seems so unLexus-like to not be smooth at all times. Any ideas?

[GreyBeard]

my lexus LS400 revs high for about 2 mins, but if i'm in a hurry, i just put the footbrake on hard and pull shift into drive (well, '2' usually cos i overrun the 'D'!). there is a slight lurch but nothing major. i don't move it out of 'D' at all til i switch off (i know some people put it into 'N' while the traffic lights are red). i believe that if it's idling cold in drive, the engine and gearbox will warm up quicker because it's got something to pull against.

[maneesh]

My car has always had a jolt when moving into D, hot or cold. Like you, I took it to Lexus and they checked out the transmission and said nothing wrong. I avoid the jolt by moving from P to R, waiting just one second, and then moving to D. No jolt then.

Lexus UK make the claim that they have never had to replace an automatic gearbox on any LS400 since they started importing them in 1989. Is that really true?

The older models always idle higher for longer than the newer models.

[Daver]

It's meant to idle at that speed. It should quickly start to come down as the engine warms.

Clunks and jolts when engaging drive indicate more of a problem with the auto box.

My '90 is the same, when cold tick-over is around 1500 but it goes into gear quite smoothly!

My problem is that as the engine warms-up tickover does not drop until I stop for about 20 secs. If I drive off from cold, and drive for hours without stopping, tickover is still at 1500 at the end of the journy. Even nocking it into neutral while moving does not drop the tickover, I must actually reduce road speed to 0mph!

I think that there may be a computer that known somthing about this!

Any thaughts on this problem would be appreciated.

Dave/.

[ColinBarber]

All older Toyotas are like this, it's the way the ECU is programmed. They don't adjust idle until the car has stopped for 5 to 10 seconds. My 4 MR2s, Supra, wifes RAV4 and IS200 all do it. They also all idle at quite high speeds when cold.

My old GS300 and GS430 seem to be much better so it seems they have changed their thinking.

[chips229]

Hi,my old mk 1 mr2 when cold would idle at 2000 rpm then slowly drop back.the LS400 mk1 i looked at today when cold,checked under the bonnet before i started was stone cold and idled at 1000 then dropped back to 600 rpm,checked the aircon and it went up to 800 rpm as explained in another post i read some where on this forum.

[GreyBeard]

that's too slow, but are you sure the rev counter is accurate? if you experience no running probs, it's probably your rev counter wrong - as the instruments are run from the same PSU as the temp guage, and clock/climate display (so i understand), then when it's fixed the revs might go higher.

[chips229]

Sorry looking at the rev counter this morning it was around 1200rpm when cold,then 600rpm when warm.I cant believe how quick the engine warms up from cold in the morning up against the 24V Senator,and how much quicker the mirrors defrost when frozen.Sorry but so happy with the 400 :D :D :D :D

[maneesh]

Dude, it's so easy to forget you are in such a fine car, as you take it for granted. You really notice it when you have driven another car, and you step back into yours and go wow, this is nice, and it's all mine!! :D