1999 Toyota Aristo GS300 diagnostics. rough idle.

[Nero_slk]

Hi all,

Recently I purchased a Toyota Aristo Vertex that has been fully rebadged and imported by lexus uk.. its the prefacelift GS300 style 2jz non turbo automatic without the tiptronics... it drove nice but later it started loosing power and running rough on idle. As I'm an enthusiast and used to have an IS200 and Supra before I looked in to the common problems and found the spark plugs to be never replaced (the car is on 60k now) and the usual rocker cover leak was present which flooded some of the spark plugs and made some mayo around them... The car was standing for around 2 months so only after I drove it for a couple of days it started running rought (guess the oil pressure helped the oil to make its way out of the rocker cover and partially flood the spark plugs)

When I discovered this problem I thought that  new spark plugs, rocker tighten and a good clean will solve the issues but sadly after doing all of this the car still runs bad ;/

I tryed the diagnostic port under the bonnet where you connect 2 pins with a wire but for some reason the EML was not flashing ;/

 

Any suggestions or ideas what it could be? anything welcome, even a good tutorial how to do diagnostics on these :)

 

Much appreciated!!!

[ColinBarber]

Hi

Not really sure what you mean by imported by Lexus UK, Lexus GB do not import Japanese models.

You should get the EML flashing evenly without a fault code stored. Is the bulb working, does it come on and go off when turning on the ignition? Which pins did you connect together?

[messi]

Hi

I agree with the above, Lexus uk or GB do not import Japanese models.

I do know something about the engine though and that is the common problem on the engine you have and the Turbo engines too have a headgasket issue, also as far as I know the Vertex model is the twin turbo, if yours isn't a turbo then yours is just a normal Aristo. Remember also they use the Toyota Supra engine, and they do have a headgasket issue.

[Nero_slk]

ok so :

-I said lexus GB as the whole outside is rebadged to Lexus, the service book is present and has full lexus service history, the paperwork says gs300 sport too. vin etc match... could have been a good conversion then I guess....

-The EML comes on when you switch the ignition but comes off once you start the car so there is no actual fault.

-sounds scary with the head gasket but I would see mayo in the oil aswell? the oil looked fresh... the car would overheat aswell... havent seen any of these symptoms (buty does make sense why the EML is not lit...) Think I have 1 more thing to check for that... open radiator cap to see if any bubbles come up on idle

-pin wise... erm think it's the top of the plug... 2 connections which are close to eachother (not sure which ones as I've done it a few weeks ago and havent returned to it yet) does anyone have a proper procedure for this?
 

-I think I'm still right about the vertex edition as it has the badge on the side, it's pearl white... has the JBL sound system, touchscreen, folding mirrors, electric steering column and other wacky toys :)

To me it feels spark related and I was thinking its the spark plugs or the coil itself... but cant diagnose it that easy due to this old school diagnostic method (I have proper full on BMW diagnostic which shows things like this to me in a few secs, but was never to good with anything below odb2 ;/ )

[Mihanicos]

Make certain that you have no ignition issue. If you have HT leads to the spark plugs, check their insulation. An easy way is to look at them at night with the engine running. If you see flashing from any HT cable to anything that is grounded then the insulation is poor.

If you have a fuel filter, replace it. Check that you have no damaged vacuum tubes on the engine. Move them and bend them a little and listen for any effect while the engine is running.

Failing all the foregoing, rough idling is a clear sign that you have burnt valves or sealing problems with the combustion chamber of any cylinder. You have to remove the cylinder head to find out the cause.

If you need any further help, contact me.

Regards,

 

Chris.