It might not be as easy as putting a pressure gauge on and seeing a low reading. It may only give issue under certain conditions, it would of been modified before production if it was that easy to replicate. Not sure what the problem was with the original pumps but the decision would be do you change to a modified pump if one hasn't already been installed. It is giving the symptoms of the old pump issues so it would be high up on my list if I did need to put new CATS on, or it could even protect the ones you have got fitted. Something to think about.
P0420 and P0430 - 2006 LC (1 Viewer)
- Thread starter Colorado80
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2001LC
SILVER Star
Would be a sweet modifacation
Cleaned the TB this weekend and can't really tell any difference in throttle response or performance. Might have an increase in mpg but haven't drive it enough to know, yet. It wasn't very dirty but there was more black stuff that came off of it than I expected.
Before:
After:
I also cleaned and soaked the PCV valve, which looked new, and re-installed it.
Disconnected the battery for 30 mins while I worked on it and let it idle for 15 minutes afterwards.
Next, I'll change the fuel filter and possibly run some injector cleaner through it.
2001LC
SILVER Star
Nice job!
Wow; the VVTi TB & intake look different. Even placement of PCV hose change to both into the "plastic" manifold.
Actually, the PCV valve is at 2 o'clock in the top photo with the rusty little spring clamp. I don't know what those 2 hoses on top do.
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2001LC
SILVER Star
Thanks, I see it.
Okay, I found an exhaust leak but it is down stream of the B1S2. Actually, it is right where the catalytic converter pipe meets the intermediate pipe (or Front No.2 Exhaust Pipe in the diagram). In other words, I don't think it is affecting the O2 sensor at all since it is down stream. However, the leak is due to the flanges rusting out on top so the only solution is replacement. Anyone think that the leak could be affecting the cat efficiency test?
2001LC
SILVER Star
I've got to ask; How many here having this issue, have a rusty truck as well?
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fxxx yes.... update. I fixed my o2 sensor code. I had the bank 2 downstream sensor code and after extensive code reading, determined that it was the upstream sensor that was bad. I had smelly exhaust as the primary symptom as well as the check engine light. took it to 3 mechanics and the lexus dealer, they couldn't figure it out. upstream sensor replaced and now no check engine light! this is on my 07 lx470 with 265k miles.
Great! Did you replace it yourself? If so, was it difficult to do? Looks like the only way to get at it is from underneath.
I paid a guy to do it. I was so sick of looking at the check engine light I finally took it to a really good mechanic who is also a friend of mine. cost me 400 dollars: 200 for the part, 200 for labor.
I suspected it was the upstream sensor, but was sick as hell of throwing money/parts at the problem. prior to this I replaced the downstream sensor twice, put in a spacer, replaced all the spark plugs, etc.
took it to the guy I bought it from.... He had it a week and swapped in an aftermarket cat. 20 miles down the road the check engine light went back on. emissions gremlins SUCK.
Here is the good news! Truck is running much better, and no more stinky exhaust. I think the faulty sensor caused the truck to run rich, which made the engine run "not right."
I drove the truck 3k miles with the damn check engine light on, including a 1500 mile trip to orlando and back. Loving this rig!
So, it still has the aftermarket cat in it and no MIL? That's encouraging. I could put aftermarket cats in and use the non-fouler downstream O2 sensors and be done with this or I can go OEM cats and use OEM AF/O2 sensors. I have the upstream A/F sensors (brand new) ready to go in so that is something I want to do next, for obvious reasons. I have read that the aftermarket cats don't last very long before they rust out, but my OEM pipes are rusted to the point of replacement after only 10 years.
is your exhaust smelly? the best advice I can give you is to hook it up to really good diagnostic equipment. we watched the upstream sensors working, and bank 2 was running higher volts then bank 1, and it was not fluctuating as much. It was subtle, but it was there. this was the "tell" that suggested we should replace the upstream sensor.
Truck is running with an aftermarket cat and all is well. pissed that they swapped the cat without asking me... would have preferred oem.
Truck is running with an aftermarket cat and all is well. pissed that they swapped the cat without asking me... would have preferred oem.
I have studied the performance using Techstream but was looking mostly at the downstream sensors. I'll DEFINITELY study the upstream ones a lot closer now before I replace them. Earlier in this thread I posted an excerpt from a paper on catalyst efficiency which basically said that if the upstream sensors are "aged" then the system would not know it and the exhaust would not pass an emissions test.
I don't think I have "smelly" exhaust, though, but my smeller ain't want it used to be. Sounds like it would be obvious.
Those part numbers are reversed on that page. Almost drove me crazy til I figured it out. The upstream and downstream are reversed. Someone pointed it out in the comments on that page but he never changed them. Don't be fooled and order the wrong parts. I've already changed my downstream and now I'm going to change the upstream. Had I not already planned to change both, I would have ordered the wrong parts.
234-4260 are downstream O2 sensors
234-9051 are upstream A/F sensors
So, the exhaust leak I have is the in the intermediate pipe. I have located a new OEM pipe but I need to know which gaskets to use and which bolts and nuts are required. All of the the parts are on the website for the pipe but I don't know which parts I need for the pipe. The gaskets I need are the ones circled below.
Anyone know which gaskets and bolts/nuts are needed?
The pipe itself is not leaking, just the mating surface where it connects to the catalytic converter pipe. A new gasket might just stop the leaking but there's no way to know until I disconnect it.
I may have to replace the catalytic converters at some point but I am content with fixing the exhaust leak for now. Yes, it would be easier to do it all at once but I just don't want to spend the money right now. We have had several costly household expenses this month and I just don't want to spend anymore.
Anyone know which gaskets and bolts/nuts are needed?
The pipe itself is not leaking, just the mating surface where it connects to the catalytic converter pipe. A new gasket might just stop the leaking but there's no way to know until I disconnect it.
I may have to replace the catalytic converters at some point but I am content with fixing the exhaust leak for now. Yes, it would be easier to do it all at once but I just don't want to spend the money right now. We have had several costly household expenses this month and I just don't want to spend anymore.
2001LC
SILVER Star
I've not done this on a 100 series, but you should just need the gaskets you've circled. Wire brush the expose threads of bolts, and soak with penetrating oil. Would be nice to have new bolts & nuts on hand, in case you snap off (break) the bolt.
I've seen an older 100 series with leak in exhaust Y pipe, no CEL or issue other than noise with it. The leak was where the hanger bracket pulled out of it's weld, leaving a ~3" x 1" hole.
What happen to your pipe?
Do you think this leak may be your problem or parts of it?
I've seen an older 100 series with leak in exhaust Y pipe, no CEL or issue other than noise with it. The leak was where the hanger bracket pulled out of it's weld, leaving a ~3" x 1" hole.
What happen to your pipe?
Do you think this leak may be your problem or parts of it?
Rust. Thats what happened. Part of the flange where it mates to the DS cat pipe is just gone. Plus, the intermediate pipe has a flex joint in it and there is some soot on it. The troubleshooting flow says to check for exhaust leaks first thing when those codes are triggered. Besides, can't hurt to test it to see if that is the problem. It's on the right bank (DS) which is the one that consistently throws the P0420 code.
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- Thread starter
- #140
The PCV valve on mine is on the valve cover on the DS underneath a foam boot.
Short Version Update: P0430 is gone. P0420 is still there
Money/Parts Thrown at it so far:
1. Plugs done (sk20r11)
2. Thermostat done (toyota)
3. Oxygen sensors replaced with denso oem
4. Cats replaced (aftermarket)
5. Electrical checked
B1S2 is still reporting lower voltage ~ .09 v. I have no exhaust leaks as this has been a California/Colorado truck most of its life. I think I may have a fueling issue, so onwards to the fuel pump + fuel filter as mentioned earlier by @2001LC . I did have the truck shut off on the continental divide around Breckenridge. In other threads, that have had the same shut off issue, all signs were pointing to a fuel pump but nothing definitive.
@KYLandy - I feel your pain.
Any other thoughts from anyone are most welcome.
