I had a set of Thorley Long Tube headers installed on my '09 GX470 a couple years back. Since then I've been clearing the P0430 and P0420 codes daily. I'm wondering what the latest best option is to avoid throwing these codes every time I reach highway speeds is. I reached out to Burtman (who I bought the headers from) but it's been months without a reply.
Best Option For Thorley Headers CEL Avoidance? (1 Viewer)
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Install a 90 degree O2 spacer for each of the downstream O2 sensors. I have two like this one (previously available on Amazon but no longer) and have zero CEL's with my DT LT headers. Others have been buying the spacers from Big Daddies Garage since Amazon no longer carries them.
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Thanks! I'm certainly aware of the search function for this problem but as you've shown, the products often become discontinued. Thank you for linking the respective products.
It might not be header-related.
Have you done the gas cap or Charcoal canister?
Gas gap Relieved mine a bit for a while, but charcoal canister was the root course for my Po430 code.
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I got a YotaWerx tune. Was the missing piece of the puzzle that tied all the other upgrades together.
Thanks!
Stupid question incoming:
Since the long tube headers eliminate the OEM cats, do you get noxious exhaust fumes? Like, when you’re idling at a light, can you smell your own exhaust?
These headers are on my list to install this year. Georgia is weak on emissions tests, and the long tubes have lower install costs than the shorties. But I don’t want to smell my own exhaust while driving.
Since the long tube headers eliminate the OEM cats, do you get noxious exhaust fumes? Like, when you’re idling at a light, can you smell your own exhaust?
These headers are on my list to install this year. Georgia is weak on emissions tests, and the long tubes have lower install costs than the shorties. But I don’t want to smell my own exhaust while driving.
The exhaust smell is certainly different after installing the LT's. I also did the DT Y-pipe so I lost all (4) cats, which I'm sure added to the exhaust flavors I now have.
You don't smell anything while the vehicle is in motion, but if you leave it running in the driveway and get out to throw something in the back, you'll smell her.
It's smellier that OEM for sure, as indicated above. But I never smell it while driving. If the GX is warming up in the morning and I'm loading the cargo area (either as part of being a DD or while camping), you do notice it. Not noxious, but not something I like taking a big whiff of.
I would have gone with STs if they had been available. When I bought mine DT had them backordered and would not commit to a production date. I waited 4 months and then was able to snag the only set of LT's they had available. They are also a no-weld install, unlike the STs. I like the LT power, but would have probably done ST's in a perfect world.
FYI I still have the OEM Y-pipe and the two downstream cats, and plan to keep them. So my GX is "half catted".
LT to HO Gesi with O2s. Works like a peach.
That setup is probably similar (albeit better flowing 
) than LT headers and the OEM Y-pipe. OEM Toyota cats are supposed to be really good, so maintaining the D/S cats would seem to be similar from a smell perspective to an aftermarket/custom Y pipe with aftermarket cats.
) than LT headers and the OEM Y-pipe. OEM Toyota cats are supposed to be really good, so maintaining the D/S cats would seem to be similar from a smell perspective to an aftermarket/custom Y pipe with aftermarket cats.
STs = Remove/unbolt OEM manifold and upstream cats, cut up the OEM manifold off of the upstream cats, install the ST headers, mock up and tack weld the stainless OEM cats to the stainless ST headers, remove the mocked-up units, fully weld, then re-install for good. The header nuts are very hard to get to due to the tubes being scrunched up against the cylinder head. All 4 OEM cats are retained.
LTs = Remove/unbolt OEM manifold and cats, re-install the LT headers in place of both. No welding required. The header nuts are still hard to get to but not as bad as the ST headers. Only 2 OEM cats are retained (in the Y pipe behind the header).
Either way, it's a nightmare job. Mine took me 2 or 3 days with LTs - see my build thread. I would not attempt the STs unless you have a shop do it or have the capability of welding the 304 stainless headers to the 409 stainless OEM exhaust (or a friend who has that capability).
LTs = Remove/unbolt OEM manifold and cats, re-install the LT headers in place of both. No welding required. The header nuts are still hard to get to but not as bad as the ST headers. Only 2 OEM cats are retained (in the Y pipe behind the header).
Either way, it's a nightmare job. Mine took me 2 or 3 days with LTs - see my build thread. I would not attempt the STs unless you have a shop do it or have the capability of welding the 304 stainless headers to the 409 stainless OEM exhaust (or a friend who has that capability).
Mine goes LT down to flange, then new flange with first O2 shortly after, GESi HO cat, secondary O2. 2.5" pre to 3" post cat. I use 2 90 defoulers downstream and OEM O2s in up and down stream. I sometimes get low codes on long highway runs but never city or wheeling. I just run an OBDII with OBD Fusion and clear them if they do come up while driving. The 03 mapping is WAY more easy to tolerate change. Same with 04. vvti makes the engine a snob.
