Guys, I have been a member here for a while, but did not post much. I have 2009 Lexus GS350awd bought it last November and already put 40,000km on it with a great success and barely any issues.
Currently GS has 217,000km and has following upgrades:
BC coilovers
FSport Sway Bars
LCA bushings (FIGS)
Short Ram Intake with K&N filter (FIGS)
Transmission flushed
SeaFoam clean of injectors and upper manifold
MAF cleaned

Now the problem is that I noticed that everywhere it claims that GS350awd should be in mid 5sec 0 to 100km or some sources claim 5.1 to 5.3. Anyways, did multiple runs running with traction and VCS off, A/C off, cooler night temperatures around 19 degrees Celsius premium gas with no ethanol and my results are 6.5sec to 7.2sec on GPS phone applications.

Overall car drives fine, gas consumption is normal no CEL was on. Just curious why am i so slow, my friend who has 2004 BMW 328 completely stock is half car ahead of me.... It is very frustrating, am I missing something in my maintenance?

 

I think those mid 5 second numbers are for the RWD cars. From what I've seen published, the AWD cars should be in the low-mid 6 second range because of the extra hardware weight and the additional mechanical friction that result from the AWD components..

 

No my awd is 5.5 sec to 100km stock with winter tires. RWD is 0.1 sec quicker, 460 is 0.4 sec quicker and 450h almost same as 460. Depending on your driving habits, some cars of the same models are faster than others.

 

That's good to hear! I haven't timed my 09 AWD. I was just reporting what I have read from various references online.

 

 

 

Spark plugs were changes when I first got the car. Must say even though original spark plugs had close to 200,000km they did not look bad and the gap was almost perfect

 

It is not about 0 -60 time, it is about of a loss of power. 1sec in 0-60 acceleration is 50 to 70hp loss at the top end... which tells me something is wrong...

 

Does anyone knows if GS has a fuel filter? Is it possible that on high rpm's it's lacking fuel?

 

Just did a bit more research and it seems that my aftermarket intake can cause a significant power loss. Will get it removed in the next few days and will update you guys on the results

 

 

Just to clarify, I use premium gas on Shell or Petro Canada, with identical results. Spark plugs were recently changed too.

 

Update:

Replaced my short ram intake with original airbox and cleaned my throttle body while working in that area. Did a few runs, seems that acceleration went even more down, now I was getting 7sec to 7.5sec... Tried few different ideas,but... When I set my app to measure acceleration from 5 - 100km/hr I get 5.5 - 5.7sec, when measured 0-100km/hr it 7 - 7.5sec. I think my app just starting to count time too soon. Will put my intake back later today and will do a few more runs to see how it is.

Must say car sounds and feels soooo much better with an intake!! No way I could go back to regular air box setup...

I will also be at the track this weekend for some lapping event and will report how are my laps compared to few months ago.

 

Any update?

 

I had my 2009 GS460 for 9 years. I drove it for 150k kilometers. That's under 100k miles.
Although I had modified teh car, I can assure you there was a loss of performance as the car aged.

I would like to point at the primary cats. As those are part of the headers, usually no one ever replaces them. And since after market headers were not available for that model, these cats would clog up eventually.

I am 70% convinced of this.