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Just a thought here:

As there are heaps more LS400s in the USA might there be merit in asking their forums specifically ?

Malc

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Just a thought here:

As there are heaps more LS400s in the USA might there be merit in asking their forums specifically ?

Malc

Yep, I posted the details up yesterday, there must be somebody who can shed some light on this.

The LOC (USA & Canada) thread is here.

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Its the American forums where I found the info about pressure caps and temp sensors.

Good luck, fingers crossed for you.

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Well, there is nothing wrong with that engine.

It's been with Thor Racing at Coventry, who have gone well above the call of duty and comprehensively checked out the engine and systems. Just about everything has been checked and analysed, most of the list below re-checked and also: Ignitor swapped for a known servicable unit, same with the ECU, Throttle Position Sensor, Fuel pump and control, etc.

Time was running out, so I have the car back now and will run it for a while.

One last theory is that the car seems to go into a self imposed limit of 4000 RPM. The tech at Thor and I (whilst on the way home), note that when the throttle is floored and the car reaches this 4000 RPM limit, moving the shift lever has no effect, I had it in 'D' '3' 'L' and even 'N' whilst it kept driving along. As soon as you lift off and it comes out of this region, you can move the shift lever and the box shifts accordingly.

The updated list is below of things already checked / to check:

Already checked:

Exhaust & Catalytic Converters checked

Valve timing checked

EGR valve cleaned & checked, pipes also checked

Throttle Body & Plenum Chamber cleaned

Distributor Caps, Rotor Arms & HT Leads replaced (Old Spark plugs were not suspect so replaced after new ones tried)

Engine sensor connections checked

Gearbox shift position sensor (confident this isn't at fault)

Fault code 21 cleared with new Oxy Sensor

Fault code 28 cleared with new Oxy Sensor

Throttle position sensor checked

MAF Sensor unpugged: Check engine light is on, engine runs rough and won't rev up much

Battery off for 30+ mins: Was disconnected at the dealers

Air Filter replaced

MAF Sensor (another one tried), this would be the third on the car

A temp sensor or faulty water pressure cap (I'll discount these as just about everything like this has been checked now)

Coil Packs

ECU

To Check:

Gearbox

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Can you do me a favour and open the fuse box in the and remove the EF1(20amp) fuse to clear the error codes held within the ecu for more than 10 seconds or more.

Put back in and go for a run and after a few miles read the new codes.

Also tell me when the car hits the fault of 4000 for the first time after clearing the codes does the engine check light flash once or light up until you take the key out.

After reading the above does the car when free wheeling at speed allow you to put the gears into N and allow you to rev past the 4000 and then go back into drive D and try again and still hits the 4000 limit. Hopefully you'll know what I mean.

Baz.

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Can you do me a favour and open the fuse box in the and remove the EF1(20amp) fuse to clear the error codes held within the ecu for more than 10 seconds or more.

Put back in and go for a run and after a few miles read the new codes.

Also tell me when the car hits the fault of 4000 for the first time after clearing the codes does the engine check light flash once or light up until you take the key out.

After reading the above does the car when free wheeling at speed allow you to put the gears into N and allow you to rev past the 4000 and then go back into drive D and try again and still hits the 4000 limit. Hopefully you'll know what I mean.

Baz.

Thanks Baz, I checked for error codes the day after I got it back but there were none. So it's not producing any but will regularly check this.

When you hit the 4000 rpm limit, there are no warnings or flashes.

...However, if (whilst driving) you slip it into N you can rev past 4000. If you then put it into D the limit seems to be there and it slows down until it reaches the speed it would be at that RPM, then just sits there. Will give this another go though.

When I checked the Transmission fluid yesterday (all warmed up after a drive, cycled through the gears and left it in P with the engine running, etc.) the level was right up to the top of the HOT mark, in fact, over that part of the dipstick and slightly onto the cable. So it's not low on fluid.

Will try the rev-up and floor the throttle routine tonight, to see if it still drops to 4000 RPM.

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Can you do me a favour and open the fuse box in the and remove the EF1(20amp) fuse to clear the error codes held within the ecu for more than 10 seconds or more.

Put back in and go for a run and after a few miles read the new codes.

Also tell me when the car hits the fault of 4000 for the first time after clearing the codes does the engine check light flash once or light up until you take the key out.

After reading the above does the car when free wheeling at speed allow you to put the gears into N and allow you to rev past the 4000 and then go back into drive D and try again and still hits the 4000 limit. Hopefully you'll know what I mean.

Baz.

Thanks Baz, I checked for error codes the day after I got it back but there were none. So it's not producing any but will regularly check this.

When you hit the 4000 rpm limit, there are no warnings or flashes.

...However, if (whilst driving) you slip it into N you can rev past 4000. If you then put it into D the limit seems to be there and it slows down until it reaches the speed it would be at that RPM, then just sits there. Will give this another go though.

When I checked the Transmission fluid yesterday (all warmed up after a drive, cycled through the gears and left it in P with the engine running, etc.) the level was right up to the top of the HOT mark, in fact, over that part of the dipstick and slightly onto the cable. So it's not low on fluid.

Will try the rev-up and floor the throttle routine tonight, to see if it still drops to 4000 RPM.

Hi Mudguts

Waited to hear how your diagnosis went after my last post on this subject,I suggested then there may be a problem with the information transmitted between the engine and gearbox within the ECU ,Having read your post this morning I now feel your problem still lies in the Gearbox and could be related to back pressure readings from the transmission fluid sensors .It sounds like the ECU is receiving info from the gearbox that is instructing the engine to go to safe mode,This is the mode that prevents damage occuring in the gearbox after a working part as failed, it normally puts the car in second gear and does not allow it to change up so a limited progress can still be made,although this is not the exact scenario the fact you can rev beyond 4000 revs when in neutral leads the cause to the gearbox and the information it is transmitting.

I had a similar problem when I first bought my car and the second gear solenoid failed and it would not rev up beyond 4000 revs and would not change up. It might be a faulty solenoid as they work with the back pressure within the gearbox to gain the optimum moment to facilitate a smooth gearchange.

Have you tried the diagnostic codes for the Gearbox as you will get these showing any faults on the electrical curcuit within the gearbox.

These are read through the ect light on the dash.

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Can you do me a favour and open the fuse box in the and remove the EF1(20amp) fuse to clear the error codes held within the ecu for more than 10 seconds or more.

Put back in and go for a run and after a few miles read the new codes.

Also tell me when the car hits the fault of 4000 for the first time after clearing the codes does the engine check light flash once or light up until you take the key out.

After reading the above does the car when free wheeling at speed allow you to put the gears into N and allow you to rev past the 4000 and then go back into drive D and try again and still hits the 4000 limit. Hopefully you'll know what I mean.

Baz.

Thanks Baz, I checked for error codes the day after I got it back but there were none. So it's not producing any but will regularly check this.

When you hit the 4000 rpm limit, there are no warnings or flashes.

...However, if (whilst driving) you slip it into N you can rev past 4000. If you then put it into D the limit seems to be there and it slows down until it reaches the speed it would be at that RPM, then just sits there. Will give this another go though.

When I checked the Transmission fluid yesterday (all warmed up after a drive, cycled through the gears and left it in P with the engine running, etc.) the level was right up to the top of the HOT mark, in fact, over that part of the dipstick and slightly onto the cable. So it's not low on fluid.

Will try the rev-up and floor the throttle routine tonight, to see if it still drops to 4000 RPM.

Hi Mudguts

Waited to hear how your diagnosis went after my last post on this subject,I suggested then there may be a problem with the information transmitted between the engine and gearbox within the ECU ,Having read your post this morning I now feel your problem still lies in the Gearbox and could be related to back pressure readings from the transmission fluid sensors .It sounds like the ECU is receiving info from the gearbox that is instructing the engine to go to safe mode,This is the mode that prevents damage occuring in the gearbox after a working part as failed, it normally puts the car in second gear and does not allow it to change up so a limited progress can still be made,although this is not the exact scenario the fact you can rev beyond 4000 revs when in neutral leads the cause to the gearbox and the information it is transmitting.

I had a similar problem when I first bought my car and the second gear solenoid failed and it would not rev up beyond 4000 revs and would not change up. It might be a faulty solenoid as they work with the back pressure within the gearbox to gain the optimum moment to facilitate a smooth gearchange.

Have you tried the diagnostic codes for the Gearbox as you will get these showing any faults on the electrical curcuit within the gearbox.

These are read through the ect light on the dash.

Thanks for the input Gents, I will digest this all tomorrow. One thing I plan to do is have a look at as much of the wiring and plugs connected to the gearbox as I can get to.

On the drive home tonight I tried putting the car in '3' and easing it up past 4000 RPM, which it did. It then did something really weird:

If I just slowly accelerated, it did just that but if I pushed the throttle pedal harder, it was like it cut the fuel off, it was as if it was working in reverse...

As far as the diagnostic codes for the gearbox go, I connected Te1 and E1 in the small round socket in the drivers footwell, the result was the check engine and ECT Power lights just flash on-off-on-off with no codes.

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Can you do me a favour and open the fuse box in the and remove the EF1(20amp) fuse to clear the error codes held within the ecu for more than 10 seconds or more.

Put back in and go for a run and after a few miles read the new codes.

Also tell me when the car hits the fault of 4000 for the first time after clearing the codes does the engine check light flash once or light up until you take the key out.

After reading the above does the car when free wheeling at speed allow you to put the gears into N and allow you to rev past the 4000 and then go back into drive D and try again and still hits the 4000 limit. Hopefully you'll know what I mean.

Baz.

Thanks Baz, I checked for error codes the day after I got it back but there were none. So it's not producing any but will regularly check this.

When you hit the 4000 rpm limit, there are no warnings or flashes.

...However, if (whilst driving) you slip it into N you can rev past 4000. If you then put it into D the limit seems to be there and it slows down until it reaches the speed it would be at that RPM, then just sits there. Will give this another go though.

When I checked the Transmission fluid yesterday (all warmed up after a drive, cycled through the gears and left it in P with the engine running, etc.) the level was right up to the top of the HOT mark, in fact, over that part of the dipstick and slightly onto the cable. So it's not low on fluid.

Will try the rev-up and floor the throttle routine tonight, to see if it still drops to 4000 RPM.

Hi Mudguts

Waited to hear how your diagnosis went after my last post on this subject,I suggested then there may be a problem with the information transmitted between the engine and gearbox within the ECU ,Having read your post this morning I now feel your problem still lies in the Gearbox and could be related to back pressure readings from the transmission fluid sensors .It sounds like the ECU is receiving info from the gearbox that is instructing the engine to go to safe mode,This is the mode that prevents damage occuring in the gearbox after a working part as failed, it normally puts the car in second gear and does not allow it to change up so a limited progress can still be made,although this is not the exact scenario the fact you can rev beyond 4000 revs when in neutral leads the cause to the gearbox and the information it is transmitting.

I had a similar problem when I first bought my car and the second gear solenoid failed and it would not rev up beyond 4000 revs and would not change up. It might be a faulty solenoid as they work with the back pressure within the gearbox to gain the optimum moment to facilitate a smooth gearchange.

Have you tried the diagnostic codes for the Gearbox as you will get these showing any faults on the electrical curcuit within the gearbox.

These are read through the ect light on the dash.

Thanks for the input Gents, I will digest this all tomorrow. One thing I plan to do is have a look at as much of the wiring and plugs connected to the gearbox as I can get to.

On the drive home tonight I tried putting the car in '3' and easing it up past 4000 RPM, which it did. It then did something really weird:

If I just slowly accelerated, it did just that but if I pushed the throttle pedal harder, it was like it cut the fuel off, it was as if it was working in reverse...

As far as the diagnostic codes for the gearbox go, I connected Te1 and E1 in the small round socket in the drivers footwell, the result was the check engine and ECT Power lights just flash on-off-on-off with no codes.

Hi Mudguts

Sorry for misleading you the ect light is not the light that is used it is the O/D light.

Procedure for reading the diagnostic codes as per workshop Manual;

O/D Off indicator light inspecton,

1 Turn the ignition switch to on

2Check if the O/D OFF indicator light lights up when the O/D switch is pushed out to off and goes off when the O/D switch is pushed in to ON.

If the O/D OFF indicator light blinks a malfunction code is stored in the ECU memory.

Diagnostic code check

1 Turn the ignition switch to on but do not start the engine.

Push the O/D switch to ON, warning and diagnostic codes can only be read when the overdrive switch is ON If it is OFF the Overdrive OFF light will light continuosly and will not blink.

3. connect Te1 and E1 in the car or on the engine connection blocks.

4Read the diagnostic code indicated by the number of times the O/D OFF indicator blinks

If the system is operating normally the light will blink 2 times per second continously.

If the system is normal then it is unlikely that the rev problem is in the Gearbox if it does not function as above you will need to count the blinks and momentary pauses between the sequences of the blinks to determine the code.

ie code 42;

gap of 4 seconds when nothing happens then the light goes on and off 4 times every 0.5 second then a gap of 1.5 seconds then the light goes on and off twice every 0.5 seconds then a gap for 2.5 seconds if there is another fault code that will follow if there is'nt then a gap of 4.5 seconds and the first code will repeat.

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Thanks for this info ambermarine. Mine has no O/D light or switch but you can drive it with the O/D off by moving the shift lever from D to 3.

I did another check today for fault codes but there were none.

What I can try is the procedure above but using D and 3 rather than O/D on or off (my car doesn't have this switch).

Something else a bit weird to report: I sat in the car today and it still has the same behaviour but now the limit seems to be 4400.

I have a couple of long motorway journeys tomorow, so will try a few things. Also I have some ramps so next time I am off I'm going to check the wiring and plugs to the gearbox as far as I can.

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Certainly one would want to get this fixed since the car is designed to go beyond that and so there is a problem which cannot get better, but on the other hand I'm not sure how much I would want to spend in time or money to fix this given the average prices of these cars and the fact that, in normal driving, I for one never see much more than 2000 rpms and that's not crawling.

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Ah, but the beauty of kickdown to 5000 revs !

Malc

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Thanks for the contributions Gents.

GEN has a point, this car cost less than £900 but I have spent another £1400 or so just trying to diagnose what the fault is. Having said that, the car is in very good condition, there are no knocks, bumps or problems with the suspension, it drives straight, etc. Some of this money has been spent on replacing faulty components such as Oxy Sensors and cleaning out throttle body, EGR system, etc. Also the Rotor Arms, Distributor Caps and HT leads have all been replaced.

Four things are remaining to fix:

Loose wiper blades (require a new motor and will eventually get around to replacing this but can live with it)

I need to re-fit one of the headlamp washers (just requires a little time)

The radio lights need replacing (been quoted £70, once radio is removed, which I can do)

The Drivers heated seat doesn't work (this I can live with)

Other than that lot, I can service it or have an independant do some of this.

On the drive back last night I learnt that I can probably adapt my driving style to get around this problem: By using the ECT Power mode and knocking the overdrive off by using '3' rather than 'D' I can get this car to give adequate performance.

Once I get a chance I will be looking at the Gearbox conections though, as I think this is pretty much the end of the line as far as enquiries go. Once that is eliminated I'll probably live with it until I change for a LS 430.

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I think I'm going to live with my Mk3 forever BUT if I don't, there's all sorts can happen, I would probably go straight for a LS460.

One reads of some issues with the LS430 !

Malc

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...Just one thing, I have thought of is a faulty Knock Sensor?

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...Just one thing, I have thought of is a faulty Knock Sensor?

Worth a try but I think you would have heard it pinking when you floor it, if it was that?

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...Just one thing, I have thought of is a faulty Knock Sensor?

Worth a try but I think you would have heard it pinking when you floor it, if it was that?

It makes no sound other than the normal, so I don't think it is pinking when it limits itself.

Just checked the fault codes today and there are none.

I have done around 3000 miles in this baby now and have come to the conclusion I am going to have to live with this. I'll get the plugs changed next month (these have been previously eliminated) and have given it an oil and filter change, so it's in good shape. It has a slight popping from the exhaust which hopefully I will get looked at at the same time.

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It makes no sound other than the normal, so I don't think it is pinking when it limits itself.

Just checked the fault codes today and there are none.

I have done around 3000 miles in this baby now and have come to the conclusion I am going to have to live with this. I'll get the plugs changed next month (these have been previously eliminated) and have given it an oil and filter change, so it's in good shape. It has a slight popping from the exhaust which hopefully I will get looked at at the same time.

You didn't call your car Christine by any chance, did you? :unsure:

Pretty much the only things I can think of, which you may already have eliminated, are either a vacuum leak somewhere, or an air leak after the MAF sensor. Other than that, I reckon you'll just have to say it's haunted by the ghost of Ralph Nader (or maybe Ralph Nader's dad, as the man himself is still with us).

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The Wheeler Dealers on Discovery are buying cars from people, flog it to them, let Ed China fix it and then buy it back, gotta be cheaper than experimenting yourself..... :whistling:

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Well, no news is good news. I have done nearly 5000 miles in this car since purchase and also sold the registration for £500, which has helped with the spend so far.

I have found some more info on Lextreme:

I have the same issue in my gs 400... have had it for the last 3 years... have tried quite a few things to fix but alas have not found a solution... Thanks for your post MUDGUTS...

I was curious about your final post confirming the gearbox is the issue... Did you finally find a way to trick the engine over the 4000rpm?

Also when I did a live monitor of my car driving I found that the ECU thought it was achieving redline rpm's of approx. 6400 when it was only at 4000... did your car do this aswell?

...monitored through the OBD port and a TIS cable plugged into my laptop usb with techstream software...

Also:

Just another quick Idea. I have been thinking really hard over this one and have had one vehicle that had stock ecu and had a similar issue.

We ended up fitting an aftermarket ECU to it but when we fired it up it was having trouble with the Cam/crank decoding.

We removed the LH cam sensor ( the Aftermarket ECu only used the crank and onecam sensor) and found that the internal sheilding and insulation had deteriored and was touching.

The cam sensor worked fine at low rpm but not up high. I thought it was worth a mention. Cheers

I found some other info on Just Answer here. The tech mentions:

1993 was that last year Lexus used a obd system before switching to the DLC3 connector compatable with all obd2 scan tools

My car is a 1997 and I have a round port in the drivers footwell and a rectangular one under the bonnet. I would like to buy a fault code reader but which one should I get? Could I connect my car up to a laptop? I have been checking for codes by connecting Te1 and e1 in the round port, (none are showing).

As always any contributions welcome

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Well, I have done over 10,000 miles in this car now with no change to the original symptoms.

It's had 4 new tyres and is still driving nicely.

No fault codes have ever appeared.

I fixed the loose wipers with a replacement wiper motor (thanks benfur) and apart from a replacement temp sensor and a couple of bulbs, it's given no problems.

Regarding this 4000 RPM problem: I have a sneaky suspicion it's the knock sensors, I'll be considering getting this looked at.

As always, any contributions welcome

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You could always try a can of bg44k it might clean a few items up you never know your luck.

My car seems to be running a little better and its about half way through the treatment cycle.

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I've only read the last page, but if this applies to your car, I would have thought it's a big clue as to where the fault might lie

" Also when I did a live monitor of my car driving I found that the ECU thought it was achieving redline rpm's of approx. 6400 when it was only at 4000... did your car do this aswell? "

I'd be looking at how the rev limiter works, then checking the components involved in that process.

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Well, I have done over 10,000 miles in this car now with no change to the original symptoms.

It's had 4 new tyres and is still driving nicely.

No fault codes have ever appeared.

I fixed the loose wipers with a replacement wiper motor (thanks benfur) and apart from a replacement temp sensor and a couple of bulbs, it's given no problems.

Regarding this 4000 RPM problem: I have a sneaky suspicion it's the knock sensors, I'll be considering getting this looked at.

As always, any contributions welcome






Hi MUDGUTS, no wonder you find no fault codes - how to read and clear diagnostic codes:
http://www.lexls.com/tutorials/intro/codereading.html

Tools Needed:
  • Short piece of wire (90-94 LS's).................UCF10/11
  • Short piece of wire (95-97 LS's) connector DLC1/17pin and DLC2/23pin
  • OBDII code reader (98+ LS's).........LS400 UCF20/21......

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I have found another port for diagnostics underneath the engine cover, see pics:

IMG00275-20120805-1722.jpg

IMG00276-20120805-1723.jpg

...Could this be OBD2?

There is the normal round port under the drivers side panel near the pedals and this is the one I have been using to check for codes by shorting TE1 and E1. I assume the garages I have been taking it to are doing the same thing, they have referred to various codes for oxygen sensors, etc.

Does this look like a ODB2 port?

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  • Club Hybrid Poll

  • 207 Hybrid Reliability

    1. 1. If you were to consider buying a Hybrid model over 5 years old, would you be worried about the reliability of the Hybrid system?


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