LS400 Help Needed

[Fringfordjohn]

As a regular reader of this forum, but only an occasional contributor, please could I ask for some advice. I am the proud owner of a 1999 LS400 Mk4 which I have owned for the last fifteen years, and during that time it has been totally reliable, apart from a couple of minor problems both of which I was able to put right with the help of this forum.
The current problem might be a bit more difficult however, as due to illness and the need for a minor operation, I have not been able to drive my Lexus since just before Christmas. In the interval between then and now the car has lived in a dry garage with the Battery connected to a Ctek Battery charger. When my daughter in law asked me last week if I could take her to the airport and as I am now fit and well I though great, a chance to get back in the Lexus.
The car started instantly as it normally does and I reversed out of the garage. As it had stood for a while I left the engine running and went to check the tyre pressures which was just as well, as whilst I was doing so the engine suddenly stopped and no amount of cranking would induce it to start again. I managed to push the car back into the garage, and took my daughter in law to the airport in my wife’s Renault.
I tried it again a couple of days ago, and again it started instantly, so I left it running and once again, after somewhere between five and ten minutes, the engine just stopped and nothing would induce it to start up again.
Yesterday I tried again, and this time after half an hour the engine was still running, but when I tried blipping the throttle, it wouldn’t rev above 3000rpm, and whilst doing so it was misfiring like mad and the engine check light was flashing on and off. When I released the throttle it went back to a normal tick over, but once I switched it off, again it refused to start.
So what to do now. I normally use Lexus Oxford for my servicing, but they are fifteen miles away, and I doubt that it would drive that far without stranding me beside the road. The car was working perfectly when I last used it just before Christmas. Whatever the problem is its obviously related to engine temperature, as the car starts and revs cleanly whilst it is cold, but once its warmed up it won’t rev or restart.
Not sure what to do now, any advice would be much appreciated. Many thanks.

 

[Venator]

Hey,

Sounds like it could be a crankshaft sensor problem, do you have a code reader to read what fault is showing?

[Titch LS]

John and Venator, I agree, it could be the Crankshaft Position Sensor or even a dodgy Air Idle Control Valve but a code reader won't be of any use as a Mk4 is OBD1 compliant not OBD2 as on LS 400's for the American market. Googling 'LS400 E1 and TE1 diagnosics' will help bring up a tutorial on how to retrieve the more basic OBD1 codes for the 1999 LS.  (It's not difficult , you only need a paperclip). This, I would suggest would be the first step toward solving this problem. 

[Malc]

just thinking ..........  if you have RAC or AA or whatever " At Home " breakdown cover might that be a route to go down ?

Even if it's just to get you to Lexus Oxford.

Malc

[royoftherovers]

1 hour ago, Malc said:

just thinking ..........  if you have RAC or AA or whatever " At Home " breakdown cover might that be a route to go down ?

Even if it's just to get you to Lexus Oxford.

Malc

Or Breakdown cover with your HOME insurance ?

 

Regards

John

[Fringfordjohn]

Thank you Malc and John, and yes I do have AA Homestart. If all else fails I will try to get them to transport the car to Lexus Oxford for me.

However before I do that I was hoping that someone with more knowledge than me might be able to give me a clue as to what is wrong with the car. If it only needs a sensor changed I could probably to that myself, thank you Venator and Titch for your suggestions. I can do straightforward jobs on cars, I have a box full of tools, but I'm afraid my knowledge dates from the days of contact points and carburetors. Also I don't have any means of determining error codes I'm afraid.

What's really puzzling about this is that the car was running perfectly when I put it away just before Christmas, so what can have happened to it whilst it was just standing in the garage for a couple of months. Its a mystery.

[Malc]

....  electrical gremlins often are  !  .  a mystery that is

Malc

[Titch LS]

John, your car can show you basic error codes, (but not by using a generic code reader). The code(s) will show up as a series of blinking dash lights when the diagnostic port on top of the engine (a small black rectangular box with flip up lid) is shorted with a paper clip using E1 and TE1 terminals. An alternative diagnostic port with the same terminals is found low down under the steering wheel column/ dash area. It's all fairly straight forward if you follow the online LS400 tutorial. A retrieved code will point you in the right direction for your problem. You can  google that code and it will come up with the likely fault area.

[Fringfordjohn]

Many thanks for that Brian, I've found the socket under the bonnet and I've read the tutorial. Have to leave it till tomorrow now as its my 75th birthday today and the family are coming round for lunch. I don't think they would appreciate me disappearing out to the garage. I'll let you know how I get on tomorrow.

[OldTrout]

A very long time ago when I fiddled about with motorbikes, the petrol cap air admittance hole sometimes got blocked. The engine would run for a bit but then die because it was starved of fuel. Reving made it die sooner. Left for a while enough air managed to bleed into the tank so that this behaviour could be repeated.

I don't know how air admittance is done now (emissions) or back in 1999 but could you just try running without the petrol cap?

John

 

[Fringfordjohn]

OK, visitors now gone so I've been out to check the LS.  The diagnostic socket under the bonnet has lots of holes where connectors should be, but only five of them have any metal connectors in them, and unfortunately the TE1 socket is one of the ones with no connector. The socket in the car is a completely different shape from the one under the bonnet, being much smaller. Again there are lots of spaces where connectors should be but again only five have any metal connectors in them This socket has OBD2 molded into its lid.

I assume this means that I need an OBD2 scanner. There seem to be many available on eBay and other places at prices from £20 to £200, but they all say that they are only suitable for cars made after 2002. My car was registered in March 1999.

It would seem from reading the sales information from the firms selling these scanners that you need to know what the car's protocol is. Does anyone know anything about this. I would be quite happy to buy one of the less expensive scanners if it would enable me to track down the problem, but I don't want to mistakenly buy one that's incompatible with the car.

Once again, any advice would be much appreciated.

John, thank you for your reply, I will try running the car with the petrol cap removed to see if it makes any difference.

 

[Hawk01]

I don't know about foreign versions of the LS, but I have a OBD2- socket in my LS400 from -99, but no regular OBD-reader works.

[Titch LS]

Yes, only American market LS400's have an OBD2 socket that actually works with a code reader. Here in the U.K., the OBD2  socket only works on the LS430 model onwards.  All  LS400's here  are OBD1 compliant even though they have the OBD2 port/socket. Hope this helps.

[Fringfordjohn]

Thank you all for your replies. As we are now a long way from the original thread, I'll start a new one on OBD sockets.

[Redsteve]

Hello John.

Sorry to hear you are having troubles.

I know it is a long shot but have you tried disconnecting the Battery and leaving it disconnected for a while to see if that "resets" whatever has changed when you parked up your car for winter?

The fact it was fine before and now it is not points (to me) to it being and electrical glitch and quite often they can be cured by Turning It Off And Turning It On Again.

Good luck.

Steve.

[Fringfordjohn]

Many thanks Steve and no, I haven't tried that. I'll give it a go tomorrow and see what happens, I'll let you know the result.

Kind regards, John.

[Fringfordjohn]

Hi Steve,

Many thanks for your suggestion but I'm afraid that it made no difference. I left the Battery disconnected for a couple of hours and when I started the car up again it ran perfectly normally for about ten minutes before it cut out on its own and then refused to restart. I left it until it got cold again at which point it fired up normally once more. Its still a mystery

Anyway thanks again for your suggestion, it was certainly worth a try.

[Spacewagon52]

Start it again and make sure the air-con is ON. I was wondering if it could be a dirty throttle body as I had this on my previous MkIII LS400. The aircon on gives it more reves after it has warmed up. Just a thought.

[Fringfordjohn]

Hi David and thank you for your reply. I tried it with the air-con full on yesterday but unfortunately it made no difference, It was certainly worth a try though, as I normally run with the air-con turned off.

What happens is that the car starts and runs normally until the temperature gauge reaches a point just below normal operating temperature, at which point the engine starts misfiring and eventually it will stop. It will then not start again. Once things have cooled down and the engine is cold once more it will start up again immediately and run normally until the same temperature is reached when the misfiring starts again. It must be one of the temperature controlled sensors, but which one and how it has malfunctioned just by standing in the garage is a mystery.

Luckily I do not have to rely on this car as I have another, but it would be nice to get it fixed. I'm afraid that the legendary Lexus reliability seems to have deserted me, at least for the moment.

[Titch LS]

It's called being 17 years old. Arthritis is setting in.

[The-Acre]

Now I know that a Lexus is a different beast to a Vauxhall, but my wife's car had an identical problem. We had the crankshaft position sensor replaced but it made no difference.  After doing some research it pointed to the coolant temperature sensor.  Some have said the CTS can be called the master sensor as it can affect many different areas in the engines running.  I replaced the sensor, which on her car took 60 seconds and the problem was gone. A possibility?  On the Vauxhall it didn't show any fault codes.  It would always start from cold, and often, but not always, chug to a halt as it got hot.  Once it cooled down it would start again. The part for an LS is about £10.

[Titch LS]

Could well be, and they're not too hard to fit on a Mk4. either. As a reasonably cheap part I would try replacing this first and then go down the more expensive garage/dealership diagnostic route. You never know it might just work. A new CTS is pretty good maintenance anyway after 17 years.

[The-Acre]

48 minutes ago, Titch LS said:

Could well be, and they're not too hard to fit on a Mk4. either. As a reasonably cheap part I would try replacing this first and then go down the more expensive garage/dealership diagnostic route. You never know it might just work. A new CTS is pretty good maintenance anyway after 17 years.

I've just spoken to a very good mechanic explaining the issue, immediately he said CTS, so I would certainly be trying that.

[Fringfordjohn]

Thank you all once again for your replies. Phil, your description of the problems with your wife's Vauxhall are exactly what I have happening here.

I looked on eBay, just to get an idea of what the temperature sensor looked like, there seem to be two types one with a plastic plug on it and one with a single spade. I assume the one with the single spade is for the temperature gauge in the dash, and the one with the plug is connected to the engine ECU. However when I looked under the bonnet of the car, after removing the plastic cover on the top of the engine, I couldn't see anything that looked like either of them. Can anyone tell me where the one that is connected to the ECU would be situated? Many thanks in anticipation.

[ambermarine]

Hi John

 

The sensor for the ecu is located on the top of the left bank of the engine looking from the front it is near the front and you will need to remove the plastic cover and air inlet pipe to the plenum chamber that runs from the air filter.