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Removing Cat's on USA spec 2003.5 Esprit With Sport350 ECU


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Hey Guys-

I've recently acquired a US spec 2003.5 Final Edition Esprit and have a few questions about removing the cats. I have already used the search function and found minimal amounts of information that was helpful, and am hopeful that someone with a US spec car can chime in! The previous Esprit I owned, a '98, had the Lotus Red Race ECU installed which only pulled readings from the front 02 sensors which allowed the car to run fine without the cats. My current car's ECU has the Sport 350 or High Torque flash and I'm lead to believe looks to the secondary 02 sensors for readings as well. I'd like to remove the cat's and am OK with a CEL coming on occasionally; however, I'm concerned that the ecu will limit boost if it's sensing irregular readings from the secondary 02's. Obviously one way to figure this out is to just have the test pipes installed and see what the effect is, but Im curious if there is anyone who has de-catted a US car and didn't have the red race ecu? I'm also curious if anyone has had experience with cat simulators? They seem to work fine for many American and Import vehicles; however, I'd be weary of installing them on an Esprit. Looking forward to any input!

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So I guess you bought Payman's car?

Anyhow, the S350 code will throw a code if you remove the cats but you can solve that by spacing/shielding the rear o2's using using spark plug non-foulers.

'03.5 Final Edition Esprit ~ 5.7lbs/hp

mildly modded - 430rwhp, 353rwtq

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You are correct the Red ECU ignores the post cat O2 sensor. From everything I've read the boost table does not take into account the effectiveness of the Cats. Removing the Cats will result in a MIL light being set. (error P0420 or P0430). There are O2 simulators which are 555 timer chips which simulate the lean- rich switching of the O2 sensor, but you would have to find the right "switching rate" to keep the ECU happy. You could look at the normal post )2 sensor switching rate and voltage levels with a scope and use that to set the simulators. The Esprit would be no different that any other engine with the simulators.

Wayne

Hey Guys-

I've recently acquired a US spec 2003.5 Final Edition Esprit and have a few questions about removing the cats. I have already used the search function and found minimal amounts of information that was helpful, and am hopeful that someone with a US spec car can chime in! The previous Esprit I owned, a '98, had the Lotus Red Race ECU installed which only pulled readings from the front 02 sensors which allowed the car to run fine without the cats. My current car's ECU has the Sport 350 or High Torque flash and I'm lead to believe looks to the secondary 02 sensors for readings as well. I'd like to remove the cat's and am OK with a CEL coming on occasionally; however, I'm concerned that the ecu will limit boost if it's sensing irregular readings from the secondary 02's. Obviously one way to figure this out is to just have the test pipes installed and see what the effect is, but Im curious if there is anyone who has de-catted a US car and didn't have the red race ecu? I'm also curious if anyone has had experience with cat simulators? They seem to work fine for many American and Import vehicles; however, I'd be weary of installing them on an Esprit. Looking forward to any input!

The Older I get the Faster I was

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Thanks for the responses guys, and yes Gonzalo, this is Payman's car. Havent had too much time to drive it yet due to poor weather conditions, but the car is exceptionally clean and very strong. So I've decided I'm going to go ahead and have a set of test pipes fitted. I'll have the rear 02 sensors spaced far away from the front 02's and see how long it takes the car to throw a CEL. If it does, which Im assuming it will, I'll have the shop use the spacers for the rear 02's. Hopefully that will do the trick, but if not, I'll look to the cat simulators as the next option. I'll keep you posted! Happy Holidays as well....

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