Potential problems following Warm-up Cats removal ?

[Anonymous]

A Toyota specialist warned me that the main cat may become "overloaded" if the pre-cats (or "Warm-up Three-way catalytic converters" to use Toyotal official jargon) are removed. Additionally, an imbalance in the readings between the 1st two O2 sensors and the main cat O2 sensor can trigger a fault in the Engine ECU (the "Check Engine" light may go on). Apparently this has happened on other Toyota models...

In some countries, the emissions test (smog test) may involve reading the Engine ECU. This is the case here in Switzerland (on recent cars anyway). So gutting the W-U cats could be a problem...

Therefore, I am looking for a second hand exhaust manifold that I can gut out whilst keeping the original one (just in case I do not pass the emissions test anymore)...

Has anyone (lucky enough to have a TRD manifold for example!) got one lying about the place?  

Cheers,

John

[dieamond]

A french guy is gonna sell his gutted exhaust line
I gave him a good deal on a used PPE line (300e), so he won't sell this too high I hope.

Mr Phat, can you spend more time on your gearbox and less on forums ?
Some are waiting for your opinions on the swap

Thank you


  s:lol: :lol: s:lol:    s:lol: :lol: s:lol:    s:lol: :lol: s:lol:

[GSB]

A Toyota specialist warned me that the main cat may become "overloaded" if the pre-cats (or "Warm-up Three-way catalytic converters" to use Toyotal official jargon) are removed. Additionally, an imbalance in the readings between the 1st two O2 sensors and the main cat O2 sensor can trigger a fault in the Engine ECU (the "Check Engine" light may go on). Apparently this has happened on other Toyota models...

In some countries, the emissions test (smog test) may involve reading the Engine ECU. This is the case here in Switzerland (on recent cars anyway). So gutting the W-U cats could be a problem...

Therefore, I am looking for a second hand exhaust manifold that I can gut out whilst keeping the original one (just in case I do not pass the emissions test anymore)...

Has anyone (lucky enough to have a TRD manifold for example!) got one lying about the place?  

Cheers,

John

Hmmm, lets take this one bit at a time;

1/ Overloading the main cat... This is the same cat that toyotas own mods dept. TRD, dont mid "overloading" when they delete the "Warm Up Cats" with the TRD header... So if the main cats good enough for them to do it, theres no real reason why you shouldn't

2/ The "imbalance of readings" works using only one of the sensors in the manifold, and is compared agianst the reading of the 3rd O2 sensor after the main cat. Put simply it works like this; The exhaust gasses come out of the cylinder and are measureed for oxygen content to calculate and adjust the fuel air mix, thats their primary job in life.

As an additonal "health check" measure, the reading from Bank 1 is compared against the reading from the 3rd O2 sensor over a period of time. If the O2 content is different at the 3rd O2 sensor, then something has happened to change the gas. i.e. its been through a cat and had its chemical composition changed. If the reading is the same, and remains the same for a period of time, it indicates to the ECU that the cats, (weather theres 1 or 3 of them) aren't working properly, the ECU then lights up a CEL, but the running of the engine remains the same.

To make this happen you need a cat that no longer works, you can do this with age, high temperature, leaded fuel, but not by simply pumping exhaust gasses through it. The main cat will simply catalyse as much of the gas as it can, and any gas left over will pass straight through. The actions of the main cat will always be enough to generate the differential in O2 readings required for the ECU health check. Bearin mind that the cat has been shown to work with turbo applications, which will typically increase the amount of gas the cat has to work on by up to 50%

3/ Reading the ECU wont tell you weather the pre-cats are present or not. all it does is allows access to the voltage readings from the O2 sensors. which will give an indication of weather the cats are working or not. What reading the ECU does do is allow the tester to see if the engine is running correctly and switching between closed loop / open loop control as nessesary. The only true way to test emmisions is to test the gasses themselves.

Hope this helps you... At the end of the day the cats are better out of the car, due to the minimal amount they do when they work and the maximum amount of damage they do when they break. My bet is you'll pass an emmisions test (even one as strict as the Swiss one) without them. If not, then someone will always be able to lend you a spare.

[Anonymous]

Mr Phat, can you spend more time on your gearbox and less on forums ?
Some are waiting for your opinions on the swap

Thank you


  s:lol: :lol: s:lol:    s:lol: :lol: s:lol:    s:lol: :lol: s:lol:

Ha! patience, patience Die...   s:wink: :wink: s:wink:   Maybe you will see the results soon at the Circuit de Charade (I hope I will be able to go and demonstrate what a Spyder should have been capable of had it been fitted with the *correct* gearbox right from the start   s:D s:D   )

The LSD is being swapped this week, so the C56 GB should be ready to be refitted this w/e.

I will check if you can change the ratios individually (depends if you can remove the cogs from the input / outpu shafts)... I'll let you know!

For the manifold, I got his message just now about his manifold... waiting for his pm...

P.S. Any news regarding the Fujitsubo "Legalize dope" (Legalis R) exhaust?   s:wink: :wink: s:wink:

[Comer]

Just out of interest, how many people so far have passed the MOT emissions test following the removal of their precats??

[dieamond]

Comer > a french guy passed with PPE header + cat + postert exhaust

[GSB]

Mine's been checked just out of interest, and it passed just fine.

[dieamond]

Ha! patience, patience Die...   s:wink: :wink: s:wink:   Maybe you will see the results soon at the Circuit de Charade (I hope I will be able to go and demonstrate what a Spyder should have been capable of had it been fitted with the *correct* gearbox right from the start   s:D s:D   )

Me I'll just show you how french people drive better  s:-D :-D s:-D

I will check if you can change the ratios individually (depends if you can remove the cogs from the input / outpu shafts)... I'll let you know!

Thank's. I'll take a 3 seconds handicap for that  s:lol: :lol: s:lol:

P.S. Any news regarding the Fujitsubo "Legalize dope" (Legalis R) exhaust?   s:wink: :wink: s:wink:

not yet
tomorrow I think

[Anonymous]

GSB: Cheers for your info

If I really cannot find a second hand manifold soon, I think I will gut the "wee shites" out anyway! Can't take the risk of them blowing my 1zzy!

[mph]

Just out of interest, how many people so far have passed the MOT emissions test following the removal of their precats??

Me! Err, and I have no main CAT either   s:shock: :shock: s:shock:   A slight bit of tweaking was required, but I blame the turbo for that   s:wink: :wink: s:wink:   CO was fine, just the HCs were something around 8-10% (can't remember now) over the limit.

In some countries, the emissions test (smog test) may involve reading the Engine ECU. This is the case here in Switzerland (on recent cars anyway). So gutting the W-U cats could be a problem...

Irrelevant. The primary O2 sensors are located before the pre-CATs so would gutting would make no different. The third O2 is only there to confirm the working of the primary CAT, no more.

[Anonymous]

Just out of interest, how many people so far have passed the MOT emissions test following the removal of their precats??

Me! Err, and I have no main CAT either   s:shock: :shock: s:shock:   A slight bit of tweaking was required, but I blame the turbo for that   s:wink: :wink: s:wink:   CO was fine, just the HCs were something around 8-10% (can't remember now) over the limit.

Emissions test in the UK must be a bit of a joke if you can pass without a catalytic converter...   s:) s:)

[Anonymous]

Everything in the UK is a joke unfortuntely!

[Anonymous]

Everything in the UK is a joke unfortuntely!

Heck, I thought that only applied to us (USA)!   s:wink: :wink: s:wink: