I agree. though I am interested to see people findings in testing other dampers

 

I ordered them on ebay from cs performance. I paid extra to have a Dynamic flow matching to within 2% set and also conversed with them before purchase to clarify what the flow matching meant. Here is the certificate that came with my set

flow matching certificate


The only slightly frustrating thing was I have no idea which injector was which as they weren't numbered in the bags. Its a minor worry given that within 2 % sameness has got to be better than the old ones from the factory.

I don't notice any smoke puffs. I do see the usual condensation clouds on cold mornings.

exhaust now smells good and dry to touch when warm (ie when holding hand in exhaust stream). It used to feel clammy/slightly sticky when it made rotten egg smells. does that make sense?

 

Hey All, so quick update...

I got around to putting in the new O2 sensors in October and after resetting the ECU the car now finally consistently gets 26-29mpg (8-9l/100) on the highway including running aircon constantly.

The other change having studied the oil recommendations in the owners manual closer, I now run it on 10w-40. 5w-30 according to the chart is too light for Australian air ambient temperatures (generally 32-120 degrees farenheit/ 0 to 50 degrees celcius). 2 observations - the oil level has stopped dropping between changes and the occasional startup rattle hasn't been heard since.

The fuel trims still fluctuate about a bit in the -6 to +2 but the car runs smoothly, economy is where it should be so I'm not going to worry much about it anymore.

Quick note on O2 sensors - clip on the left hand side was royal pain in the *** behind the heat shield, right side very straight forward beside the sump, no heat shield. Anyone know why Lexus didn't make them both the same as the right side? I can't see any logical/physical reason why both sides have different clip positions.

Happy motoring!

 

The "10W" is the cold start value in the "10W-40".
... 90% of wear occurs on cold-start up...


Go with 0W-40 synthetic.

 

Did you change all 4 o2 sensors? Would you mind sharing which brand you went with?

 

In answer to the last post - I used Denso O2's - just the sensor 1's. Sensor 2's only really monitor the Catalytic convertors.

Ok so roll on a 18 months or so, a couple of lockdowns later etc. and it's time for a quick update on this saga.

Latest thing - I got P0330 & P0325 codes (knock sensor circuit malfunction) a bit before Christmas. Limp mode absolutely sucks to drive with.
Ordered genuine sensors and waited for 3 weeks for the new sensors to arrive. Installed them pretty much straight away once they arrived.

Aside from clearing the error codes, which was to be expected, there were a few other pleasant surprises. Such as
- The car goes really really well now - better than I ever have felt it.
- Its smooth and lots more power throughout the rev range. but especially above 4000 rpm. It used to run out of puff a bit but now pulls strong all the way to the redline.
- Fuel consumption has dropped to the lowest that I have seen it - despite enjoying the new found acceleration a bit.
- The intermittent hesitation (or less power than you'd expect at times) that was present before has completely gone. And so far hasn't returned.

As a result of these unexpected improvements, I have a feeling that the 20 year old originals have been on their way out ever since I bought the car back in 2018.
Most likely failing knock sensors were the root cause of the randomness in smooth operation. Sometimes it would run pretty well, sometimes a little rough for seemingly no obvious logical reason. And a general feeling that there was less power than it should have for a v8.
Perhaps failing knock sensors were telling the computer that there was knock present when there wasn't any knock. Would certainly go a way explain the intermittent nature of the hesitations

A couple of other observations on knock sensors
- Knock sensors are easy to change but it's a pain in the backside to get to them under the manifold - so you don't want to have to do it twice.
- Genuine sensors are expensive.
- Genuine sensors can take a while to arrive.
- Definitely only use genuine knock sensors if you only want to do it right the first time.
- Good opportunity to replace brittle plastic electrical connectors at the same time
- Had I known knock sensors can be failing without throwing a code, I would have replaced them as a maintenance item at the start. Hindsight is a hard earned thing.

I now consider this particular mission of "chasing the smooth running" finally accomplished.
And with benefit of time I can now reflect on what made actual differences in getting to smooth powerful running

The were parts that made the biggest improvement to the cars running. These were:
1. Renewing all old cracked vacuum hoses & PCV. (I recommend anyone/everyone with cars this old to do this as step one. Followed by a close second tidbit of clean the MAF)
2. New VVT solenoids (originals were very broken, throwing codes when I bought the car. If yours still work fine there is no need to change them)
3. Knock sensors.
4. Changing to the correct oil weight for our air temperature range

Good things to do as part of maintenance and/or to rule it out as a cause. Not sure they made any difference in my case, but certainly didn't hurt either.
1. Clean MAF sensor / replace with new DENSO MAF
2. Refresh O2 sensors
3. New Plugs
4. clean throttle body, air assisted injector ports/ intake manifold

Things that may have helped, but probably unnecessary with the benefit of hindsight - any benefit at the time was most likely the ecu reset placebo effect but it is nice to know they are new.
1. Flow matched Injectors.
2. New Fuel Pulse Dampeners

I hope that helps anyone who may be experiencing similar symptoms.