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Discussion Starter · #1 ·
I understand the potential problems with precats left intact but is it necessary to gut an '02 with only 21k miles, driven only occasionally and not worked hard? What about the check engine light if I gut? I was told by my excellent mechanic not to gut but watch for any loss of power, etc. in case they go bad. Any suggestions? Thanks-
 

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I only had 32K on my '02 when I took the manifold off, the precats were intact. BUT, everything I've heard suggests that if you wait until there's a problem, you've waited too long.

I can't prove that, but I understand the reasoning behind it.
 

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Precat

You can monitor the top part by removing the two o2 sensors and using a flashlight. Take a close look to be sure the honeycomb hasn't started to deteriorate. Gutting them will not cause engine warning light. The precats are only usefull when your engine is cold, once at operating temp your main cat does all the work. Toyota and Nissan both had problems with ceramic precats, nissan warrantied a lot of engines I believe. Because you have an 02 I would seriously consider removing, after the 2003+ updated models are less prone to engine dammage. If you wait for loss of power it is already too late. I gutted mine.
 

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I understand the potential problems with precats left intact but is it necessary to gut an '02 with only 21k miles, driven only occasionally and not worked hard? What about the check engine light if I gut? I was told by my excellent mechanic not to gut but watch for any loss of power, etc. in case they go bad. Any suggestions? Thanks-
Pre-cat failure is a random event. It isn't related to age or mileage. No one (except maybe Toyota, and they aren't talking) knows what causes the pre-cats to fail. There may be multiple causes.

When I removed the pre-cats from my wife's Spyder, it was nine years old and had over 120,000 miles on it. The pre-cats were perfect.

I have read reports of pre-cats failing at only 23,000 miles.

If the pre-cats fail, the smaller debris particles are sucked into the cylinders and the larger chunks lodge down-stream at the main cat where they plug the exhaust. The plugged exhaust is responsible for the loss of power. The small particles score the cylinder walls beyond repair. If you wait for this to happen, you've waited far too long.
 

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If you wait too long your excellent mechanic will have to replace the shortblock or put another engine in. Will you will hav eto pay your excellent mechanic for, which will be excellent........for the mechanic...:lol:
 

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I bought my car second hand. It's engine have had a total boom in 30K miles (49000 km). Yes, because of cats. Ged rid of the cats asap..
 

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If you wait too long your excellent mechanic will have to replace the shortblock or put another engine in. Will you will hav eto pay your excellent mechanic for, which will be excellent........for the mechanic...:lol:
And replace the main cat and precat or the entire cycle will repeat itself. The mechanic legally can't recommend that you alter or defeat an emission system component.
 

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I never got an engine light when I gutted mine. Gut it while there's still something to gut. Or, else your engine will gut it for you.:p
 

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Discussion Starter · #11 ·
Thanks to everyone for their input....will be gutting the precats this week.
 

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When I did mine I used a pressure washer to thoroughly wash the inside. Another nice touch is to spray the heatshields with high heat manifold paint, it really cleans up the engine bay (unless yours look new already)
 

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It's really easy to do. Just be careful taking the sensors out (There is a socket for it). You want to replace the gaskets while you're at it.
Yes, you need the manifold to block gasket, and 2x of the manifold to downpipe donut gaskets. i think its like 20 something dollars for all 3. the part numbers are available in the instruction threads

also. you will want to get some pblaster or liquid wrench. i let my nuts soak in the stuff for 3 days before tackling the project
 

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Yes, you need the manifold to block gasket, and 2x of the manifold to downpipe donut gaskets. i think its like 20 something dollars for all 3. the part numbers are available in the instruction threads

also. you will want to get some pblaster or liquid wrench. i let my nuts soak in the stuff for 3 days before tackling the project
Yup, and don't go cheapo on the gaskets. The extra 10 bucks for oem will save you from having to do it twice with paper gaskets.
 

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Discussion Starter · #17 ·
Did it today...really not too hard of a job with the car backed up on ramps. The precats looked fine for a car with only 21k miles but I took everyone's advice and did it. Why risk an engine failure, especially if toyota won't fess up to their problem?
Thanks to you all for your input. And the oxygen sensors don't know the difference.

Mark
 

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If you wait too long your excellent mechanic will have to replace the shortblock or put another engine in. Will you will hav eto pay your excellent mechanic for, which will be excellent........for the mechanic...:lol:
^made me LOL hard.

glad to see it done, mine were in perfect condition too when i pulled them, but every bump, grumble knock, rattle, thought of poor acceleration scared me stupid on a daily basis while the cats were still in there. the peace of mind is worth it. enjoy the spyder :icon_thumright:
 
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