so emissions are coming up and my car has had P0420 & P0430 codes for basically this entire year and i kept clearing the codes hoping they would go away eventually, but they never did.

I replaced all o2 sensors but that didn't fix the Catalyst Efficiency Below Threshold codes for both banks, but I'm glad i replaced them since they all had 257k+ on them.

I was then stumped and convinced I would have to drop $500+ on new cats.

Then I was browsing these forums and realized when i cleaned my air mix path i didn't do it properly. I cleaned the 8 little holes but didn't realize there were two bigger holes that are the most important to be clean. Pic for reference:

Attachment 419552

I cleaned those two little holes with the car running, with throttle body cleaner and compressed air and my car started blowing a bunch of smoke out the exhaust, but only when i used the compressed air after the CRC TB cleaner.

After using a whole can of throttle body cleaner in the air mix path, I shut the car off, unplugged the battery for 15 min, then took the car for a drive and definitely noticed a difference in throttle response and shifting smoothness.

I ended up driving 100+ miles and realized the CEL never came back on! What a surprise, i figure maybe the air mix path was clogged and making the ECU think something was wrong with the cats, but who knows. I plan on cleaning the air mix path again soon, in case i missed any gunk in there.

Goodbye P0420 & P0430!!!

Nice work. Our '92 had a lean issue but it was the two upstream O2 sensors. A couple weeks after we bought it I pulled the throttle body off. Replaced the coolant temp sensor and cleaned the throttle body. That thing was a mess. I don't think it had ever been cleaned. It took a whole can of cleaner and a tooth brush and pick. After a new gasket I put it all back together and started it. The car fired up and revved high and then idled back down. Kind of like it took a huge deep breath and settled down. We live in Douglasville and took it to have the emissions done last month. The guy thought his machine or the probe was broken cause he had never seen a older car run so clean.

Cool I am going to clean my air path this weekend

Hey guys do u know of any aftermarket upper and low control arm that's out there for a LS400 1999

ebay, search on google, etc. thanks for the thread bump

did the motor mounts today. had already done the tranny mount awhile back. Car is now at 258,335. Mounts were the original ones and they were done.
Attachment 419017

battling some low idle issues on my car. Only when it's in drive with the AC off.

I'm guessing it's my idle air control valve
I'm probably just gonna clean mine and reinstall, but was curious of the part number for 98-00. I would guess it's different from the non vvti 1uz's, but maybe i'm wrong.

The only OEM part number I've found seems to be for 93-97 LS400's. Haven't found one for 98-00 yet

interesting. so it appears 98-00 ls400 don't have idle air control valves.

apparently they have electronic throttle control motors. It took me awhile to figure out but it seems as though they started this on the 98 Gs300 as well.

8967247010 is the part # for the 98-00 ls400 electronic throttle control motor

Interesting. I cleaned my throttle body and the Air Path Mox. So much junk built up in there. Surprising to me, the idle on my car went up when I did this...

replaced the cabin air filter, like most stuff on this car, seems to be original filter. It was quite nasty having 259,029 miles on it.
Attachment 418334

The looks pretty clean compared to mine that came out of my 93. It looked original as well seeing 171k miles and 23 years. Does your car have a different scent after you replaced that? my LS has a very old almost musty smell i cannot get rid of, even after replacing my filter.

my car does have a better scent now, not as musty as it was before. I know what you're talking about lol

I've bombed my car twice, febreezed my carpet like 5 times and have gone through about 15 air fresheners. still smells the same haha.

haha!

front suspension overhaul coming soon, have a bunch of parts sitting in my garage, with more on the way.

lower ball joints, lower control arms, upper ball joints & control arms, sway bar end links, inner & outer tie rods, and last but not least, strut bars! I need adjustable shocks as well but need to save up for those now!

Miata
 

Is this the same David on mx5atlanta?