I have a 2002 Ls430UL with 210K miles. Over the last few years I daily drive the car, but there are a few issues. Sometimes starting off I get a short hesitation like a hiccup. Not every time though.
Also at light throttle applications like gentle acceleration or maintaining speed on a road I will hear light detonation, like the timing needs to be advanced. If I give it more gas it goes away. This too is not every time.
Finally the car seems sluggish.
There are no codes. A shop checked the exhaust for clogged cats and found it clear. They ran a diagnosis and came up with nothing. They did a scope test for the crank position sensor and everything is okay, but they were able to determine that for some reason something was pulling the timing back -5 degrees which they thought could be knock sensors but doubtful since no codes. The other theories are problems with ecu or what the called piston slap.
The car will still pull up to 30mpg on the highway
Anyone want to take a stab at this?

 

Clean or replace your MAF. There is a tutorial on here but just make sure the wires in the top of the tube are what you are cleaning. My car had your same symptoms but worse. Cleaned the MAF, $7 for a can of CRC Mass air sensor cleaner that will last for years, and now it drives perfectly.

 

I will check it. A few years ago I changed the spark plugs and cleaned the MAF and it still persisted. I will check it again though

 

Check your vacuum hoses as well. I once chased a slight hesitation on my GS400 for months and it turned out to be a cracked hose under the engine cover.

 

i never thought of that. That’s a good point. How obvious was the crack?

 

It was right under the engine cover near the purge valve. Funny thing is, the same leak occurred on our SC430 in almost the same place. I think just over time the hoses become brittle and crack.

 

Could you post a pic of this hose and its location please?

I only ask because I finally took delivery of my LS430 a few days ago. Even though everything is fine (have done a couple of 120 mile round trips without issue), but I want to be able to do some general pre-maintenance on it as time goes on, just because.

Many thanks in advance!

 

Sure, it's the hoses in this general area. I would take a flashlight and look under the hoses as well.

 

Excellent! Thank you sir! I appreciate it!

There's a few things I want/need to do to this car, and this will help in the process. Thanks again!

 

and no codes were ever thrown?