Hi Guys,

Lexus newbie, so be gentle.

Just got a 1997 (96 MY) GS 300 mk1.

Runs fine when warm, but stalls when cold, and idle speed is slow/lumpy.

Seems like the idle control valve (£498.56 new from Lexus Leeds). Had a similar problem on a SAAB turbo, cured by my mechanic taking the throttle body apart and cleaning everything. Any ideas.

Cheers

Laurie

Hi,
My car has the same problem,but starts from cold fine and runs fine until switched off.Yet when you restart the car from warm it always starts but cuts out after 10 seconds or so.It can take a minute or more to get it to run.
I knows how you feel about the price of the idle control valve price pure greed at that price
You could try taking the valve off and cleaning/soaking it in thinners/petrol thats what i was told to try.It has made it slightly better starting,but not fixed the problem.Try cleaning it,might be worth a try.
Let us know how you get on.

Cheers chips.

Hi Chips,

GOOD NEWS. My mechanic has sorted it.

Took the throttle body off and soaked the whole assembly in a solvent bath. He then sprayed liberal quantities of carb cleaner into the Idle Air Valve, and then lubricating everything with WD40, including the electrical connectors.

Now starts perfectly and runs fine when cold. Idle speed is still a bit low (around 750 rpm) so I am going to re-set the ECU (there is a post on this) which may sort it. Plan to do this tomorrow (Monday) so will keep the board "in the loop".

So, saved myself 500 quid , but just discovered that one of the front brake calipers has a siezed piston . Explains the odd feel to the brakes, which also exhibit the usual wobble. Having new discs and pads fitted, provided I can source a caliper. So much for the legendary Lexus reliability. I have had 5 BMW 5 Series with over 100k on the clock, plus a Saab turbo with 154,00 which I sold two years ago and is still going strong, and none of them has given me any of this grief.

get intouch with Dewsury auto salvage , i know they have 2 gs300;s in (cos ive stripped em )

01924 466666
not too far from u either
Steve

Idle speed of 750 rpm, is that when cold or hot? If hot then that is correct.

Hi, thanks for your interest.

750 RPM idle speed when hot. Feels a little lumpy, but doesn't stall, and runs up smoothly with a pleasant burble when the throttle is blipped.

Maybe it is OK, but may re set the ECU anyway. It shouldn't do any harm, and would clear any error codes due to the stalling and rough idle associated with the problems above.

Regards


Laurie

YOU could try sourcing parts from the USA, normally after all costs, they still work out cheaper for certain parts

Thanks Steve.

Managed to source a reconditioned one from Andrew Page Ltd for £173 plus VAT. Not far off the price of a second hand one plus a seals kit so I may go with that. Visited Dewsbury Auto Salvage last week as part of the Idle Air Valve saga, but the throttle bodies they had were different from mine.

Gradually getting there!!

Reset the ECU using the instructions posted in the knowledgebase. The engine has started perfectly, runs fine when cold, and ticks over smoothly and quietly at around 800 as indicated on the dashboard rev counter ( I dont have a digital tachometer)

Just a final comment. This car was into Lexus Plymouth in April this year for some diagnostic work on this problem. They charged the previous owner £150 plus VAT, gave no diagnostic report above "it needs further work to ascertain the full nature of the problem". Obviously he decided to get rid before doing that, and incurring still more unnecessary costs, but I think it is outrageous that he was charged £150 and got no report, only that in effect for more money they will have another look.

My independant mechanic, who has looked after my family's various SAAB's BMW's Honda's, and Vauhalls for the past 10 years sorted this out for an hours labour, a soak in a solvent bathe, and a can of carb cleaner, less than £100 all in. Pehaps Lexus should be careful, or they will kill the goose that lays the golden eggs.


Laurie

Glad you have got it sorted out and saved yourself some money as well

Rather than start another post topic

Does the uk mk1 GS300 have the same idle control valve as the mk1 Aristo,maybe i can get hold of a secondhand one if there the same?

Cheers chips.

Not sure. I can email you a hi res image if you like. Drop me a mail to lauriemills1@ntlworld.com and I will reply with an attachment, or can llok up the part number on the actual valve

Guess what!, I have exactly the same problem for some time as well with my MKII GS. Perhaps this is common issue with GS.

Lst year Lexus Twickenham seemed unable to sort it out. After charging rediculous amount to clean the throttle body they claimed everything was fine (but actually no improvment at all).

I lived with it for a year. And now she is back in Lexus Twickenham for annual service - and guess what - they spot the problem ! and now are charging me again to look at it!"

They will be calling today - I will post the result.

meanhwile, are there more of us out there who had the same issue and have some more advice on how to deal with it.

I am really fed up paying disgusting Lexus dealer prices for nothing - could anyone advise of a repuatable non-lexus garage near the Twickenham area.

It isn't a common problem but the throttle body, MAF sensor, idle control valve and TPS should be checked/cleaned/adjusted every now and then to maintain optimum operation.

Have a look at my post re Throttle Pot (more properly known as throttle position sensor-thanks Colin). Mine is now running much better when cold, and fine when warm.

Learned of a good lexus specialist in the Reading area, a friend of my brother in law, who gave me good pre purchase advice over the phone, and seems very genuine. Bit of a trek to Reading, but you can always go shopping!!! If you want his number give drop me a mail on lauriemills1@ntlworld.com

Could anyone let me know exactly where the idle control valve is?

On the throttle body, which is situated on top of the engine, and is the unit which the large tube from the air filter goes into.

On the front of the throttle body there are two "Pots", around 30mm in diameter, looking from the front of the engine the Idle Air Valve is the left hand unit, the right hand one is the Throttle Position Sensor

I can email you a picture if you want.

I cleaned a few bits this weekend - made no difference whatsoever.

Still awfull.

Seems if you stop and re-start within half an hour or so - everything fine.

But leave it for 3/4 of an hour or more and the problem starts - at first only slight but then, the longer the gap before re-starting the worse it is.

Untill it must hit some threshold many (at least 12 ) hours later when it will be fine to start again.

Can only imagine it is temperature related, but over such a long time?


Really infuriating. I can't trust it to use. But not even Lexus seem to have any idea what the problem is. And being time-related - so difficult for a garage to actually experience.

Can anyone come up with some idea of what the problem would be.The fact that it is temp and time related must eliminate most things as it doesn't happen continuosly whicst the engine is running.

Also, can anyone advise good Lexus mechanic in the Heathrow or surrounding area. (Middlesex)

I'm wondering if I am having a simular problem or at least related to the rest of the forum on this subject. I even signed up and made a posting for help. see "car won't start when warm" I paid the $500 for the Idle control valve as my Mechanic was sure that that was the problem. I questioned it because Toyota and Lexus parts people don't even stock the item because it is a rare item to go bad. My mechanic said the error code pointed to the valve so we replaced it and that did not fix it. He is now troubleshooting our GS300 for the make-up of a non repaired diagnosis. the car has now been in the shop for a week as i suspect he looks at it when he can. we have been really frustrated with this problem. It has got to be a faulty part or a bad adjustment that fools the computer. we had the throttle body off and checked, new spark plug wires, rotor, Nipo spark plugs, fuel filter, timing belt, water pump, thermostat. I would really like to get suggestions or an answer to what is wrong. I will post mine if our mechanic figures it out.
bcnvegas

It does seem to be temperature related.My car when started when warm runs fine for a few seconds then it runs rough as though its overfueling,but theres no petrol smells from the exhaust when its running rough.I was thinking weather it could be under fueling and thats why it cuts out.It seems to cut out before the dash warning lights have chance to go out.The other thing i was thinking was that as the engines restarted and restarted the coolant is flowing through the Idle control valve each time until fresh hotter coolant,hot enough for the worn sensor to sense a difference.
I myself want to get this problem sorted and if i have to buy a new sensor then so be it,but i like you dont want to fit it only to find the problems still there.

Cheers chips.

Hi Chips,

Still struggling with a simialr problem, but have now repalced the coolane temperature sensor.

Bit of a pig to get to, being underneath the inlet manifold and its associated plumbing, but it has a green terminal, and is screwed into the water jacket. Do not buy the lexus part, it is £50 and identical to the part from my local motor factor (Andrew Page ltd), who charged <£10.00. If you are stuck, I will get you one and send it to you.

I do not think my problem is caused by the Coolant Sensor, and current opinion among Selby's (limited) car repair community suggests a head gasket proble, and slight leak into the cylinders causing the prob. Not sure, and unwilling to throw cash at is, so will keep looking and will keep the board in the loop.

Laurie

My problem is also similar!
I have a toyota soarer/lexus sc400. WHen I start the car (mainly when it is cold) it runs for a few seconds then stalls. There are no warning messages or anything. SOmetimes it takes up to 8 tries before it runs normal. GEtting the revs up do not help either. I heard it may have something to do with the air intake control or something, but not sure. Once the car actually is running properly, then its fine. The problem also sometimes happens after 15mins when it is still relatively warm...but primarily when its cold.

Does anyone know what would help fix this problem.. ? Thanks guys!

Throttle body may just need a clean, or idle control valve. I would recommend you look on the US forums, both the SC and the LS forums. Many more owners over there of the 4L V8, so you will probably find an accurate procedure to follow.