O2 sensor spacers are used to fool the downstream sensor into behaving as if there is a healthy catalytic converter. The sensors upstream of the pre-cats are there to allow the ECU to actually control the air/fuel ratio. You should never use a spacer on the upstream sensors! Whoever did this either doesn't know what they are doing or is trying to cover up a significant engine issue. I would first check to see if the upstream sensors are the correct part. If they are, install them without the spacers and see if the engine runs without throwing any fault codes. You will need an OBD code reader.

 

... install them without the spacers and see if the engine runs without throwing any fault codes. You will need an OBD code reader.

The car throws a p0420 code about once a month. The sensor does not have enough threads to attach to the cats, so I have to use the spacer. In the meantime, I applied anti seize to the treads and it seems that the leak was reduced. This is not the sketchiest thing I have seen on my car so I am not surprised. The rear crash bar was held on with one bolt and zip ties.

 

The rear crash bar was held on with one bolt and zip ties.

😱

 

I don't think a screw slot will hold up to an impact driver as well as the nut. You could try welding one night on more heat and impact gun.

 

I use a O2 spacer after my sports cat because it was throwing an error code about low catalytic performance. It just separates the O2 sensor from the exhaust gases a bit. Thats why its also called an anti-fouler. Theyre harmless but I wouldnt use them on the main O2 sensors.

 

I had to make one of these after the shop that did my inspection failed me for having the spacer: https://www.spyderchat.com/threads/....com/threads/exhaust-header-question.162452/page-2?post_id=2220788#post-2220788

 

I was reviewing my photos yesterday and noticed that the left precat was intact and the right precat was destroyed, which explains why the spacer exists. I'm not sure why the previous owner(s) would knock out one precat and not both.

In the meantime, I have ordered a thread chaser and two new o2 sensors. I still could not get the O2 sensor back on without the spacer and I'm not sure if it's the threads on the cat or the threads on the O2 sensor. I may replace the other O2 sensor if the exhaust leak comes back.

 

I was reviewing my photos yesterday and noticed that the left precat was intact and the right precat was destroyed, which explains why the spacer exists. I'm not sure why the previous owner(s) would knock out one precat and not both.

In the meantime, I have ordered a thread chaser and two new o2 sensors. I still could not get the O2 sensor back on without the spacer and I'm not sure if it's the threads on the cat or the threads on the O2 sensor. I may replace the other O2 sensor if the exhaust leak comes back.

It probably disintegrated rather than being knocked out 👀

 

ECM doesn't monitor precat efficiency based on the sensors, no need to use a spacer on the 2 sensors before the main cat, full stop.

 

Then my conclusion is incorrect. Perhaps the only reason why the spacer exists is because of the threads.
Edit: or because the sensor is bad.

 

For whatever reason, which really doesn't matter there should not be a spacer for an O2 sensor in the exhaust manifold. It really needs to be in the exhaust flow to work properly. It's purpose is for mixture control giving values to the ECU so it can change fuel delivery.

 

Before:

After:

 

A new bung or header if you can't find a helicoil of that size. The bung replacement would require removing the old one.

 

I was able to thread on a new O2 sensor by adding some tinned copper wire between the bung and the threads. It should be sufficient to drive the car over to an exhaust shop to replace the bung after I can put the muffler back on. I also destructively removed the heat shields around the muffler and the exhaust manifold. I wanted to inspect the muffler more closely for leaks and removing the heat shields around the exhaust manifold makes it easier to work around while I am under the car.

I cut a slot into one of the sheared studs on the precat in an attempt to use a flathead to back it out. I don't have any pictures at the moment but I ended up shearing it width-wise when trying to remove it. This was after using a propane torch and reapplying penetrating oil over the last 3 days. This was the "worst" stud out of the three because it was sheared pretty close to the manifold. Luckily this gives me a flat surface to use vicegrips on. I also have a stick welder which will be plan C. The other two studs should not be as difficult; one of them has enough threads to use two nuts on, and the other is completely intact, I should be able to use a external torx bit to remove it.

I also took the following measurements for the pipe sizes from the exhaust manifold and the muffler. I bought two gaskets for the flexpipe and one for the muffler from my local auto parts store. There were no gaskets on the exhaust manifold when I took it out, only a tiny bit of copper anti-seize from when the exhaust system was last modified. There was a gasket on the muffler, which I removed using a pick and a flathead.

 

Over the last couple of days I've been heating up the nuts holding the engine manifold to the head using a propane torch and applying penetrating oil. I would heat up each bolt for roughly 3 minutes -- put on some music and heat it up for an entire song, and then put some oil on it and let it sit until the next day. Today I went out and bought some MAPP gas from Home Depot and made an attempt to actually take off the nuts. I was able to take off all of them; out of 5, 4 of them with the stud still attached, and one with just the nut:

I have already ordered replacement studs and nuts. With this, I can take off the entire exhaust manifold without risk of shearing a stud in the engine. I still need to remove the studs on the other end of the manifold after the pre-cats. I can now put the whole manifold onto a workbench or get a replacement manifold if need to be, and I can take it to a muffler shop for a new bung.

 

I was able to get two of the mounting bracket bolts for the precats removed after applying heat and penetrating oil twice for each bolt, so four times in total.

I then hammered out the left precat which was still intact:

I have the manifold on my worktable now and am working towards getting the three amigo studs out. I can also more easily see how badly I crossthreaded the O2 sensor hole. The first couple of threads for that bung no longer exist and is now flat metal, which explains why the O2 sensor would not thread at all.

 

Don't forget to clean your engine. Your engine does have oil leak at the chain tensioner and maybe the valve cover gasket is leaking too. Because of the chain tensione's leak, check the oil level.

 

Don't forget to clean your engine [...]

I went out and bought some Super Clean Tough Task Cleaner-Degreaser from WalMart after watching Project Farm's video on degreasers and it worked surprisingly well:

I also inspected the vin plaque on the engine and can verify that the VIN on the body matches the engine.

[...] Your engine does have oil leak at the chain tensioner and maybe the valve cover gasket is leaking too. Because of the chain tensione's leak, check the oil level.

Now that the engine is cleaner I can better monitor this, I checked the oil level and it's above the low mark on the dipstick, but I could not warm up the engine because of the lack of exhaust hardware.

I was able to remove the last exhaust manifold stud from the head using the "two nuts" trick. Then I cleaned the mating surface using a fine scouring pad on a drill:

I still need to figure out how to remove the three amigos studs from the manifold itself. I used a lot of heat and a socket torx bit on the one stud that was not damaged and could not get it to move at all. Tomorrow I will try welding some nuts onto them. If I cannot get them out, I may cut my losses and just buy an ebay manifold. I was considering one from Zero Exhausts which I know is widely recommended on this forum but it is double the price, which I can't really justify for my ratty and clapped out Spyder.

 

I went and welded up some nuts to the precat studs and could not get them to budge at all. This was after days of soaking them in penetrating oil while it was still attached to the car and applying heat several times.

Obligatory "I am not a welder..." I went through 10 nuts trying to get the any of the studs to move and could not make any progress. I also tried using a hammer and a hand impact driver for the one stud I cut using a dremel, but no luck.

I went and ordered a ebay-quality exhaust manifold from kage.co.uk for ~$225 shipped and new studs and to attach it back to the engine. I could have drilled them out, but I am not confident in my ability to do it correctly, and I would still need to get the bung fixed.

With any luck, my Spyder should be back up and running next weekend.

 

You had a lot more patience with that manifold than I would have.

 

I try not to spend money on the car when possible but I don't think any of those exhaust studs are coming out without drilling or an acetylene torch. I should also add that the manifold nuts on the head came out while still attached to the studs, which suggests that the rust has really glued the hardware together.

 

I got the replacement manifold yesterday and fitted it the same day. I used two new oxygen sensors alongside it. It weighs about 5 pounds less than the stock manifold.

I needed the brackets on the original manifold, I was able to get one off but the other one is stuck on the original manifold:

fitting the exhaust back on:

I was a bit wary about the fitment of the exhaust on this part, it took me like 20 minutes just to get the bolts to thread on, and the gasket did not look like it was sealing completely:

I ran the car and it sounded a bit weird, some smoke was coming out of the exhaust which might have been the clean burning fuel I used to clean the exhaust valves and maybe some residue from the new manifold.

I checked the oil and the dipstick was dry(!) so I went and did an oil change. I pulled out about 1.25 quarts from the oil pan which was very worrisome. I did not have this level of oil loss with the last oil change. I put 4 quarts of 5W30. Also the car slipped off the jack because the jack was on uneven ground (operator error) and an object that looks like a damper broke off the rear engine/transmission mount:

There are a couple of part numbers stamped on the damper:
12351-23040
12351-23010
12351-0M020

I know the engine mounts were replaced by the previous owner because it's listed on the Carfax, so I presume the shop that did the work used a non-Spyder part. Either way it did not look like it was doing anything. The jack also bent the rear sway bar (which was very rusty) but when I removed the jack it bent back to shape.

I fit on the rear crash bar with nuts as opposed to bailing wire from the previous owner and fitted the rear bumper. I still have to put the rear taillights on but it was getting dark outside.

The new exhaust still smells... of exhaust and is still loud, so overall this has been a giant failure. At least it looks nice.

 

I know the engine mounts were replaced by the previous owner because it's listed on the Carfax, so I presume the shop that did the work used a non-Spyder part

After lurking through some posts on this forum it seems that this is a Spyder part, but I still think the part that broke off unused on the Spyder. I could not find any videos of other Toyota vehicles where this was being replaced.

It looks like my missing exhaust bracket is part 17118-22060 17118-22080 for the right precat bracket (right when viewed front-to-back). Luckily they're still available for sale from Toyota. Below is a picture from parts.lakelandtoyota.com

I'll double check to see If I can't wrangle the support off my precat, but I may have bent it out of position when hammering it to get it loose.

 

Make sure you have both brackets on exhaust manifold, it matters. Also keep a close check on your oil level has to not destroy the engine.

 

Make sure you have both brackets on exhaust manifold, it matters.

What makes you think that?

 

If using the correct parts, you're exhaust manifold will thank you

 

I took the car out on a cheeky drive and the Malian exhaust left bracket (right when viewed front to back) sheared off.

The inside cabin also smelt of burning plastic, which I originally thought was offgassing from the new manifold, but it wasn't going away. I'll double check for an exhaust leak because the smell is strongest when the engine lid is open. At this point I am not sure if I want to buy new left exhaust bracket or just send it until the car fails.

PS: It is possible that this bracket sheared off when the car fell off my floor jack, but the jack did not make contact with the exhaust, only the rear engine mount and the rear sway bar.

 

I took the car out on a cheeky drive and the Malian exhaust left bracket (right when viewed front to back) sheared off.


The inside cabin also smelt of burning plastic, which I originally thought was offgassing from the new manifold, but it wasn't going away. I'll double check for an exhaust leak because the smell is strongest when the engine lid is open. At this point I am not sure if I want to buy new left exhaust bracket or just send it until the car fails.

PS: It is possible that this bracket sheared off when the car fell off my floor jack, but the jack did not make contact with the exhaust, only the rear engine mount and the rear sway bar.

Regardless of why the bracket failed, the bracket is there to prevent the header primaries from fatigue cracking due to engine vibrations. I would get it weld repaired.

 

The combo bad engine mount + only one manifold bracket + shaking car + not a high quality header may have causing the bracket to break early. For the plastic smelling, check if a part of the harness is touching the exhaust. O² sensor, rear licence plate light harness etc.

 

I wouldn't say the engine mount is bad... I simply shaved some weight from it

I think the burning rubber/plastic smell may be the silver antisieze I applied to all the exhaust threads. I'll be able to do a thorough exhaust leak test during the weekend.
The car sounds... not great with the new header. Kind of like a fartcan, and also loud. I suspect that there is a leak somewhere which is contributing to the sound.

 

After about 45 miles the 'burning rubber' smell has largely dissapeared, I can still faintly pick it up the smell. It might have been the anti-sieze or the new manifold off-gassing. I did get a CEL for P0440 and P0446 for a failing VSV solenoid which I already have a replacement for and a pending P0420 code which I will need to take a closer look at. Both header O2 sensors are new Denso units so it just may be a undiscovered exhaust leak.

 

P0420 is low catalyst efficiency which is related to the post cat sensor. Do you still have a main cat?

 

Should be an easy fix since he now has some spare spacers