Gs300 - Who Has The Final Answer Why These Loose Power?

[Jock666]

Allright folks. Now some of these forums on the web are nearly 20 years old and the problem goes back to the very 1st lexus models - so why o why is there not a big screaming definitive answer as to why they suddenly loose power???????

It's been going on since begining to at least the 2005 models and forums are full of folks asking same question - so what is it? Based on research it's not: ECU, Injectors TB, TPS, MAF, Mechanical, Injector loom, Fuel pump, Relays, any sensors that we know of, and a specific fault code never shows up - so WTF is it????

Finally got so sick of it the car has not moved in 6 months.

Come on all you so-called Lexus/Toyota Guru's & Dealership Mechs - tell us!

[Mihanicos]

The efficiency and the power any engine produces is directly proportional to the compression ratio of the cylinders.

Worn piston rings and cylinder head valves will reduce compression ratio.

Worn valve guides will allow the valve to change seat position every time it closes.

A compression test will verify the condition of each cylinder.

Excessive oil consumption will be noticed.

A clocked or bad exhaust with worn silencer tubes will increase back pressure and this will cause the engine aspiration to drop, the cylinders will not be emptied of exhaust gases, thereby reducing the amount of fresh air and fuel into the cylinders, hence a drop in power.

The ignition timing is critical. The manufacturer gives a way of checking the ignition timing of the engine at idle speed and higher.

The engine timing is critical as well. I would check all the timing marks of the engine.

The air to fuel ratio is also critical for optimum performance. Inlet manifold vacuum should be as specified to indicate any air drawn in due to a leak.

I would check the lambda sensors to be within limits.

I would also check the ECU against a reference to confirm that it is functioning correctly and controls the engine correctly.

I hope the forgoing is of some help.

Kindest regards,

Chris.

[dave1]

I owned a great GS300 Sport from 2002 until 2008 and when I sold it it had around 150k on the clock. I had absolutely no issues with loss of power. I don't think that it is a problem encountered by many Lexus owners at all and certainly not something I have noticed as being prevalent on LOC. I only changed to upgrade to a GS430 and that also has given no power issues in my 7.5 years of ownership.

Which are the forums where people are all asking the question?

Chris has been informative above as to possible issues, maybe the cars are not being looked after correctly.

[ColinBarber]

As above there is no common issue here.

[Jock666]

Seriously - NO issue! You, presumeably, have never had cause to deal with it then so it cannot exist?

It is and has been a major problem with the motors since year one. It is also a major safety issue as the motors completly loose power (excepting the last 25% wire control) unexplicably and without warning with no lights and no codes - and is in no way an isolated issue - hence the reason for the post "final answer".

If you can name it we have
changed/fixed/kicked it - and we have all the scanners you could wish
for and the abillity to read them too..... Would not be on here trying to find the elusive "final solution" if
we had not. Just pity as with most forums that no one ever bothers to
share/give the final answer - if they ever get it - to their problem. Specifically this one.

So thanks to all who have taken the time to respond constructivly but still the problem remains and hopefully 1 day we may even stumble upon the fault/cure.

[ColinBarber]

Who said there was no issue?

I stated there is no common fault here, we don't get multiple owners complaining of this issue. I certainly never had an issue with either my GS300 or my GS430, and nor have the hundreds of owners here.

From what you describe the fly by wire throttle system could be an area for investigation. Whilst no fault codes are generated, by data logging all the sensors you would probably get a good indication of where the fault is occurring, by looking at the data when the issue occurs.

[TigerFish]

As above, I've not heard of any of this as a common issue.

Can you link to some of the others who have the same, so I can read some of symptoms there too?

Sent from my Iphone using Lexus OC

[noby76]

owned 2 Lexus models an IS and now GS and haven't experienced any loss of power both models had over 100,000 on the clock when I got them.

[Darklore3003]

Have you tried throttle body?

I know a few years ago we had one in that was lack of power, eventually diagnosed as warped TB.