What is the benefit of decat? - Page 2 - LotusTalk - The Lotus Cars Community
 
LotusTalk.com is the premier Lotus Forum on the internet. Registered Users do not see the above ads.
Reply
 
LinkBack Thread Tools Display Modes
Old 10-31-2012, 04:15 AM   #21 (permalink)
Registered User
 
addertooth's Avatar
 
Join Date: Nov 2011
Location: Arizona
Posts: 2,572
Some states (Like California) has stricter rules, but most states have the same basic rules. Some states carefully check the vehicles anually; some states do not check or enforce the rules unless you live in a major city (Like Arizona).
__________________
Storm titanium 2005 Elise with carbon fiber spoiler, BWR sway bar, BOE toe links, gPan2, LidBone, sector 111 wheel studs, Grey RAC Monolite wheels with toyo R1R, Team Dynamics 1.4 with Hoosier A6/R6s, Katana2 Supercharger, ECU with 265 flash. PPE headers w/decat, CEL angle eliminator, Silent touch catback, Rear Panel Eliminator, HKS intake, V2 fuel tank, Walbro255 fuel pump. HID lights.
addertooth is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 10-31-2012, 05:10 AM   #22 (permalink)
Registered User
 
antinym's Avatar
 
Join Date: Nov 2006
Location: Orlando, FL
Posts: 1,147
Florida doesn't check anything at all, ever.
__________________
Hmm...
antinym is offline   Reply With Quote
Old 10-31-2012, 07:13 PM   #23 (permalink)
Registered User
 
Gunpilot's Avatar
 
Join Date: Jun 2012
Location: Enterprise AL
Posts: 2,188
Images: 42
Alabama doesn't check anything either. You can drive a smoke generator here and they thank you for helping out the skeeter truck driver. I saw my neighbor throw his used motor oil away last week in used milk jugs but it's also legal to dump it in your yard.
__________________
2007 Exige mental track toy.
2005 Elise.

"Listen up, I ain't Captain Walker. I'm the guy who carries Mr. Dead in his pocket."

"CHARLIE DON'T SURF"
Gunpilot is offline   Reply With Quote
Old 10-31-2012, 11:01 PM   #24 (permalink)
Registered User
 
Secret Chimp's Avatar
 
Join Date: Jul 2012
Posts: 252
Removing the catalytic converter decreases the backpressure in your exhaust system. In order to actually see any performance gain from removing your cat, you need to have your ecu retuned.
__________________
2007 Exige S - Storm Titanium
1961 Austin Mini - restoration and turbo install in process
Secret Chimp is offline   Reply With Quote
Old 11-01-2012, 03:16 AM   #25 (permalink)
Registered User
 
irox's Avatar
 
Join Date: May 2012
Location: Chattahoochee Hills
Posts: 530
Don't know if its the same; but when I re-cat'ed my Esprit to 200 cells, I did a hard reset on my ECU causing it to retune (relearn).

But Elige have MAF, not MAP sensors... That could be the controlling item
__________________
1998 Lotus Esprit Twin Turbo

Last edited by irox; 11-01-2012 at 04:19 AM.
irox is online now   Reply With Quote
Old 11-01-2012, 12:39 PM   #26 (permalink)
Registered User
 
Secret Chimp's Avatar
 
Join Date: Jul 2012
Posts: 252
Quote:
Originally Posted by spree View Post
Don't know if its the same; but when I re-cat'ed my Esprit to 200 cells, I did a hard reset on my ECU causing it to retune (relearn).

But Elige have MAF, not MAP sensors... That could be the controlling item
I have no idea how a v8 Esprit works, unfortunately. I don't have a lot of experience with my Lotus Exige as of yet either...But I do have lots of experience with other cars.

When you remove the cat from most OBD-II compliant cars, a cel is often triggered because the oxygen sensor that sits post-cat in the exhaust is no longer happy. To be happy, the ecu wants to see a differential in the readings between the o2 sensor that sits pre-cat and the one that sits post-cat. That is how the ecu can tell that the cat is working. If it thinks the cat is not working, the ecu can/may/will do a few things.

1. It can throw a CEL. "Hey, I think something is broken. I should let the owner know."
2. It can start adjusting the a/f. "I'm seeing weird numbers. I should adjust the a/f till I see the readings I want."
3. It can stick itself into closed loop mode. "I don't have all the data I need to safely/properly adjust the a/f. As a result, I'm switching over to a map that I know will work until we get fixed."

All these things can lead to decreased performance and increase fuel usage.

So, what I'm getting at is, if you remove the cat and you do not have a way of tricking the ecu into thinking the cat is operating as it should (via adjustments to the ecu or an 02 sensor hack), you will often see no performance gain by removing your cats.
__________________
2007 Exige S - Storm Titanium
1961 Austin Mini - restoration and turbo install in process
Secret Chimp is offline   Reply With Quote
Old 11-01-2012, 01:52 PM   #27 (permalink)
Registered User
 
creaturekris's Avatar
 
Join Date: Jun 2009
Posts: 260
You will need something like this to go along with the cat delete to move the second sensor out of the exhaust stream.
O2 Simulator, angled, cel fix
creaturekris is offline   Reply With Quote
Old 11-02-2012, 02:04 AM   #28 (permalink)
Registered User
 
irox's Avatar
 
Join Date: May 2012
Location: Chattahoochee Hills
Posts: 530
Quote:
Originally Posted by Secret Chimp View Post
I have no idea how a v8 Esprit works, unfortunately. I don't have a lot of experience with my Lotus Exige as of yet either...But I do have lots of experience with other cars.

When you remove the cat from most OBD-II compliant cars, a cel is often triggered because the oxygen sensor that sits post-cat in the exhaust is no longer happy. To be happy, the ecu wants to see a differential in the readings between the o2 sensor that sits pre-cat and the one that sits post-cat. That is how the ecu can tell that the cat is working. If it thinks the cat is not working, the ecu can/may/will do a few things.

1. It can throw a CEL. "Hey, I think something is broken. I should let the owner know."
2. It can start adjusting the a/f. "I'm seeing weird numbers. I should adjust the a/f till I see the readings I want."
3. It can stick itself into closed loop mode. "I don't have all the data I need to safely/properly adjust the a/f. As a result, I'm switching over to a map that I know will work until we get fixed."

All these things can lead to decreased performance and increase fuel usage.

So, what I'm getting at is, if you remove the cat and you do not have a way of tricking the ecu into thinking the cat is operating as it should (via adjustments to the ecu or an 02 sensor hack), you will often see no performance gain by removing your cats.

It's exactly as you described (excellent desc, BTW); except for the ECU tune part. The Esprit's ECU tunes itself (learns) after a hard reset. No external tuning avail, except by tricking the sensors as you recommend. I installed bung extensions as "insurance" even though I did not do a full de-cat; only dropped from ~600 to 200 cells which should have maintained an acceptable differential.

The part I'm not sure of is if decatting changes, increases, the air flow measured by the Elige MAF sensor; whereas the Esprit measures air pressure which remains the same.
__________________
1998 Lotus Esprit Twin Turbo
irox is online now   Reply With Quote
Old 11-02-2012, 03:46 AM   #29 (permalink)
Registered User
 
Formula1's Avatar
 
Join Date: Apr 2012
Location: Florida
Posts: 341
I just installed a 2bular decat with my 2bular GT3 muffler. I didn't reset the ECU. I felt a decease in low end torque. I have a mini-cat O2 bung solution that was suggested to me by 2bular and it works great (no CEL). The question is should I reset the ECU? Will that help the low end torque loss or is that due to the lack of back pressure inherent to a free'r flowing exhaust?

Btw, I have a 2011 Exige RGB with the S260 factory tune.

Thanks!
John
Formula1 is offline   Reply With Quote
Old 11-02-2012, 08:54 AM   #30 (permalink)
Registered User
 
Secret Chimp's Avatar
 
Join Date: Jul 2012
Posts: 252
Yes, you should reset the ecu. It's usually good practice to reset after each mod.

If nothing else, it's a free and easy way to help diagnose your issue. If resetting the ecu doesn't help, the decreased torque might be normal (I doubt it though since you are supercharged) or it might be due to some other issue you created when putting in the new exhaust (air leaks in exhaust prior to o2 sensors).
__________________
2007 Exige S - Storm Titanium
1961 Austin Mini - restoration and turbo install in process
Secret Chimp is offline   Reply With Quote
Old 11-02-2012, 09:38 AM   #31 (permalink)
Registered User
 
Formula1's Avatar
 
Join Date: Apr 2012
Location: Florida
Posts: 341
I'll go ahead and reset it. Honestly, I may revert back to a cat. Since I don't plan on heavily modding my car, I just don't know if it's really worth the negative environmental impact. If so, I'll be selling the decat with the mini cat. It's been on the car for ~500 miles, basically brand new!

Thanks!
Formula1 is offline   Reply With Quote
Old 11-02-2012, 01:34 PM   #32 (permalink)
Registered User
 
Saketome's Avatar
 
Join Date: Mar 2012
Posts: 169
How do you reset your ecu?


Sent from my iPhone using Autoguide.com App
Saketome is offline   Reply With Quote
Old 11-02-2012, 01:38 PM   #33 (permalink)
Registered User
 
Formula1's Avatar
 
Join Date: Apr 2012
Location: Florida
Posts: 341
Quote:
Originally Posted by Saketome View Post
How do you reset your ecu?


Sent from my iPhone using Autoguide.com App
I assume its as simple as disconnecting the battery. Correct me if I'm wrong!


Sent from my iPhone using Autoguide.com App
Formula1 is offline   Reply With Quote
Old 11-02-2012, 02:07 PM   #34 (permalink)
Registered User
 
irox's Avatar
 
Join Date: May 2012
Location: Chattahoochee Hills
Posts: 530
Don't know about the Elise/Exige; the Esprit OBD command set supports an ECU reset... I forget the hex values... But would probably be different anyway. A battery disconnect might do it...
__________________
1998 Lotus Esprit Twin Turbo

Last edited by irox; 11-02-2012 at 05:32 PM.
irox is online now   Reply With Quote
Old 11-02-2012, 07:43 PM   #35 (permalink)
Registered User
 
Saketome's Avatar
 
Join Date: Mar 2012
Posts: 169
Quote:
Originally Posted by Formula1 View Post
I assume its as simple as disconnecting the battery. Correct me if I'm wrong!


Sent from my iPhone using Autoguide.com App


Im just wondering... How come when I disconnect and reconnect the battery the odometer trip meter reading is still the same and the radio channel and setup don't change. Unlike my other cars the trip meter goes to zero and radio channels and setup changes.


Sent from my iPhone using Autoguide.com App
Saketome is offline   Reply With Quote
Old 11-20-2012, 05:39 PM   #36 (permalink)
Registered User
 
Saketome's Avatar
 
Join Date: Mar 2012
Posts: 169
Anybody?...


Sent from my iPhone using AutoGuide.com App
Saketome is offline   Reply With Quote
Old 11-20-2012, 06:35 PM   #37 (permalink)
Registered User
 
EricH's Avatar
 
Join Date: Nov 2007
Location: Dallas, Texas
Posts: 1,039
This conversation is drifting from the thread title but -
My radio always resets.. both the time and all the stations. I've never looked at the trip odo. My Exige came factory with an Alpine CDE-9872.
__________________

Click links to see my 2008 Lotus Exige-S 240 , '99 M3, 505rwhp '89 Mustang ( sold) , '05 WRX STI ( sold) homepages or here for my spin compilation (ispunuwin)!
EricH is offline   Reply With Quote
Old 11-20-2012, 08:45 PM   #38 (permalink)
*
 
shay2nak's Avatar
 
Join Date: Dec 2003
Location: Calipornia
Posts: 21,993
you need the Lotus Scan3 tool to actually reset the ECU. go to the dealer.
__________________
** save ~10 lbs gain 1 hp ** EQ: Y=(190*X) / (1984-X) where Y is (HP) and X is (lbs)

'07 Lotus Exige S310


WTC 2
shay2nak is offline   Reply With Quote
Old 11-21-2012, 08:48 AM   #39 (permalink)
Registered User
 
Saketome's Avatar
 
Join Date: Mar 2012
Posts: 169
Quote:
Originally Posted by EricH View Post
This conversation is drifting from the thread title but -
My radio always resets.. both the time and all the stations. I've never looked at the trip odo. My Exige came factory with an Alpine CDE-9872.
Sorry for the off topic.. My elise came with a blaupunkt.


Quote:
Originally Posted by shay2nak View Post
you need the Lotus Scan3 tool to actually reset the ECU. go to the dealer.
I see, thanks.


Sent from my iPhone using AutoGuide.com App
Saketome is offline   Reply With Quote
Old 11-21-2012, 11:53 AM   #40 (permalink)
Such moderate
 
doge's Avatar
 
Join Date: Sep 2010
Location: USA
Posts: 3,576
Images: 1
this:

doge is offline   Reply With Quote
Sponsored Links
Advertisement
 
Reply

  LotusTalk - The Lotus Cars Community > Lotus Discussions > Lotus Exige



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -8. The time now is 06:30 AM.


Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.3.2
Garage Plus vBulletin Plugins by Drive Thru Online, Inc.