lxdxb

GX470 2005 (160K miles) I've had problems with P0430 P0420 codes .... new plugs , new coils, injector refurbished, new PCV, MAF Cleaned, Filters Changed, New Fuel Cap, and just changed the Air Fuel Sensors (Bank one & two) Sensor 1 ......Cats from the exit side looks clean (see pictures) I've been monitoring Cat temperatures and A/F Sensor Voltage and with O2 after the cats... from what i can gather the delta in temp before and after the cat is too high, it was a delta of about 200 oF but since i changed fuel to a higher octane (95 before now 98) the temp difference seems to be going down (delta of 150oF).. but its still not at a difference of 50oF ....I doubt i can afford to by new cats yet ... so I'm guessing my next step is to check for exhaust / manifold leaks but i cant hear anything ...

My question is if i buy a set of Manifolds with Cats from a nearby scrapyard has anyone heard of getting them flushed / cleaned ... then i can get my old ones swapped out ? or do I have to bite the bullet with new replacements which will cost an arm and a leg...




view of rear of cat Bank 1

view of rear of cat Bank 2

PCV old and New

When hot

Fuel Trim

At start up after about 10 min

At start up

Bank 2 reading below threshold

Lexus4321

A bad converter is different from a clogged converter. Clogged can perhaps be identified with a flow test, flow some CFM and measure the inlet pressure at flow. High psi means clogged converter.
A converter can go bad, just can't convert any longer. CATs work when the CAT temp is above a minimum temp.

This is an ok read.
https://parts.olathetoyota.com/p0420-code-toyota

lxdxb

Could anyone help on the data im seeing ... at a steady 3000 rpm the Sensor 2 is staying steady at 0.6 volts (good as i understand) Through normal diving its ranging from almost zero to up to 0.9volts .... and at idle Bank 1 climbs and Bank 2 drops .... Im only getting an P0430 code now on Bank 2 after I ran Liqui Molly at 1/4 fuel.... what an i looking at here? Bank 1 and 2 AF sensors are new .. do in need to have a go at changing the down stream also? any help would be greatly appreciated...



At a constant 3000 rpm locked in 3rd

Normal running

Sat Idle

Bank 2 fail

Lexus4321

What do the spark plugs look like at this point.
1-3-5-7 vs 2-4-6-8 ?

lxdxb

Plugs are 2 weeks old .. do you think i should pull them again to look?

Lexus4321

If one side cat is clogged, that issue would likely be reflected back up into the cylinders on that bank, which may (might) show up on the plugs.

What did the old plugs look like, bank vs bank?

If you get a cheap bore scope you can look inside cylinders to see what the pistons look like (do not use any slip-on attachments).

Need to collect data that the system is not giving you.

lxdxb

Off back to the UK for the next 4 weeks so the car needs to sit a while... I plan to buy a Endoscope on my return ... I was planning to look down through Bank 2 and Bank 1 number one sensors to look at the leading edge of the cats (damaged or clogged) also would like to measure back pressure ...Ill take a look at the pistons also, thanks for that ..... The plugs I took out weren't that bad TBH , it was misfiring when i bought it 6 weeks ago..I changed all the coils (few cracked) and had the injectors all reconditioned ... I'm thinking the cats are just blocked up from poor maintenance.... Ill attach a few pics of the cats from the back side .... There is a company in Dubai that will remove both cats and clean them for $150.00 maybe worth a shot, if i can confirm they look okay from the other side they will also do a carbon clean for $25.00 .. or I could try the Lacquer Thinner Trick LOL.


Downstream Bank 1

Downstream Bank 2

OLD PCV

lxdxb

Still being plagued with the dreaded codes and before I shell out for new cats; I have checked in and out temps of both cats ... 600oF before cat and 770oF for outgoing on both Bank 1 and 2 cats at 3000 rpm therefore they appear to be working, I've changed both the AF sensors and now the O2 rear sensors and I'm still getting a P0420 error flagged. Fuel Trims both long and Short look fine (so not running rich) ... I've tried running a gallon of lacquer thinner... (Scotty Kilmar method) and Liquid Molly Cat Cleaner .. no real improvement ... I would like to test back pressure on the Cats but the location of the AF Sensor is close to impossible to get to !! So maybe I could try a vacuum test to check for clogged exhaust ... But where do i connect the vac hose exactly ? I am now thinking could it be a small manifold leak ? Also I noticed when i was running the liquid molly through at 3000rpm for 30 min the Cats and and manifolds were glowing red !!! (picture taken at night) Is this normal ? my IR Gun said the temp was 600oF. Any Ideas guys? I have tried spacers but this only threw P0136 errors so i removed them ....


After new O2 sensors

O2 storage figures throwing the P0420 code

Glowing Manifold and Cat

chiph9

A cherry red cat is somewhat alarming! Don't park on any dry grass.
I have no experience with the product - try contacting their customer support?

Chip H.

zippinbye

What's your OBD II reader? Or is that from a shop? I'm in the market for something more sophisticated, but short of pro pricing; that looks awesome!

Anyhow, I had this exact problem. My normal general service shop was not willing to have me source non-OEM cats & manifolds (or have a local welder swap-in generic cats). They said "genuine Toyota is the only fix we subscribe to"), so I went to another independent general repair shop I had experience with. They were willing to do whatever, but suggested a cat cleaning first. $50 per cat. No guarantees, but stated a 80% success rate. If it did not work, fee would be applied to other solution, so what did I have to lose? I did not see their process, but the owner called it a chemical wash. It was so swift, I doubt they pulled the manifolds. Probably a spray upline from open exhaust behind the cats. A completely satisfactory solution! Eight years and as many smog checks later and these cats are still performing. A wash is an absolute must-try before doing anything major! Wash what you have before sourcing used, in my opinion.

lxdxb

Sorry for the late reply Zippinbye the reader is an OBD Link LX with their software .. i had to pay 14.99 GBP for the lexus add on.

Cats removed and cleaned but still the same issue.... I even replaced the entire EGR system.... now looking at 02 bypass system from magnum tuning..

Lexicon1

zippinbye is there any way you can find out what exact product they used to successfully clean your Catalytic converters? Your repair person may also want to know their repair lasted this long......
Great that yours were cleaned well.
thanks