Engine And Gearbox Trouble

[MiLexus]

Hi Guys. I just purchased a 95 ls400. The pre ODB2 version. I have some trouble with it so Ill put my questions and findings here.

I have some Idling problems and the car is shaking too much when idling. Just once in 2 days it suddenly shuts off the engine. It also starts to shake or stotter/vibrate when driving a constant speed between 45 MPH and 65 mph. When pulling or braking at these speeds everything is OK as well as driving speeds in a different range. Than it is just too smooth and everything feels fine. What causes this shaking or vibration at a constant speed? It does "Klunk" when Idling so I think I will change the engine mounts and Trannys as this is the solution according to some on this forum. If anyone has an other suggestion just let me know.

I have some trouble finding the right information as my engine is different than the older version. I have two big throtle valves(at least they look like that but probably only one is the throttle valve.) Where for is the valve before the throttle valve? The most of the threads on this forum show an engine that has only one big valve.

Also my fuel economy is just extreme. I can do only five km on one liter of fuel. It should be 11 to 12 according to the info from the dealer!! (When unplugging the MAF sensor the car fires up and immediately shuts down again. Idling is not possible without the MAF sensor. So ther is not much testing possible)

What can cause this incredible fuel consumption?

When I do a cold start the gearbox seems to stay in 2nd gear when pulling away. The car seems to stutter and it just has too little power in low revs to get it going normally. I must put the gear leaver in L to get some speed and even then it is slow until I come in the 2200 rpm area. Then suddenly the car pulls like crazy and seems to be a dragster.

When warm the car pulls relatively normal but still a standing start is very slow. The first 15 mph just take incredibly long. A car like this should be able to burn rubber right? When warm after the first 15 mph the car feels reliable and relatively fast but the torque I get when cold over 2200rpm is really nowhere to be found. The gearbox is slow but seems to be working better than when cold.

When I first checked the engine bay I noticed a lot of disconnected vacuum hoses. I tried to find an overview of the complete vacuum system but I could not find that in the internet for my type of engine. Does anyone have an overview of all vacuum connections? I now connected it using pictures I found on the internet of engine bays of different LS400s.

So all this looks like serious engine management problems right? It can just be one stupid little sensor that is failing.

What also is strange is that the car is registered as a '97 mod but it has no ODB2. That is why I think it is an early 95 car. Now I dont know how to get the transmission codes out of the computer as I have no OD switch. By the way. I have not even one code from the engine! So the ECU thinks everything is just fine. Still strange that he is this thirsty.

When I bought the car I had a lot of loose vacuum hoses. I think I connected the most of them correctly but I am not sure as I still have a lot of trouble with my engine and idling..

I still have one open vacuum nipple. From the Idle control valve I have a rubber hose to the main air channel/inlet(this is normal). At the end of the hose ther is the plastic connection to the main air channel/inlet but ther is a small open nipple over there with no rubber hose connected. What should this be connected with? I found a picture of a similar engine where I can see the hose is gooing down directly but I can't see where it is gooing to. Does anyone have a vacuum overview for my model? Or does anyone know where this open nipple should be connected with?

Let me know!

The car has an LPG conversion but the info above is based purely on its regular 98 octane fuel settings. The LPG does not work properly as well but I think Ill have to make the car running normal and smooth on euro98 before I bring it to a LPG specialist. Maybe the car will run fine on LPG when it is also running fine on 98. In that case I don’t have to bring it to a specialist at all.

It is quite some text but I hope people can tell me what they think I must do first. I also like to know how the gearbox gets his gear change signals and maybe anyone can tell me how to adjust the gearbox cable(if it is the gearbox cable that is connected to the throttle valve.)

I’m looking forward to your responds.

Cheers!

[ROYT]

Wow! Suggest start at the basics, check the spark plugs and HT cables first to see if thiese are causing

the stutterring, which might just be misfiring.....

I would have thought any disconnected vacuum hoses would cause

the engine to idle too fast......

If this was my car I would disconnect everything to do with LPG until

the car runs right on petrol.

[MiLexus]

Wow! Suggest start at the basics, check the spark plugs and HT cables first to see if thiese are causing

the stutterring, which might just be misfiring.....

I would have thought any disconnected vacuum hoses would cause

the engine to idle too fast......

If this was my car I would disconnect everything to do with LPG until

the car runs right on petrol.

Thanx mate! I think normally the LPG system is passive. When driving on euro 98 the complete gass system becomes inactive. So dont worry anout it now. I will try to make it run OK on normal fuel first. The misfiring is a good idea! thanx for that. It just take an hour to disconnect al the plastic crap and take a look at the sparks so I will probably do this next saturday. Is ther a way to measure the ignition cables? I also thought the LS all have a missfire sensor. Is this true? In that case it could be broken or just disconnected by the previous owner.

Ill let you gus know when I checked. Please come up with more ideas!!

Cheers!

Milko