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(Post Link) post #1 of 56 Old 15-11-11 Thread Starter
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Decat and fake cats to fool ECU?

Ive read that you can fit fake cats to fool the ECU to prevent the engine fault light coming on? Any ideas what this is?

I would really like to decat my 2002 147, but dont want to loose any gains by the ECU detecting the fault. Can the ECU be modified to prevent this? Are the gains worth it?
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(Post Link) post #2 of 56 Old 19-11-11 Thread Starter
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Can you programme the chip to ignore the cat removal?
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Maybe type 1st what engine You got
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Its a 2002 2.0 TS if that helps.
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any one?
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you can remove the cats without the need to remap, as long as the lambda sensors are still in place. i've taken my main cat out of my 147 and have no errors.
 
(Post Link) post #7 of 56 Old 25-11-11 Thread Starter
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From what I understand, you can do that on older 147 engines but not the newer ones? I have read the sensors are in different places. On the newer phase engines the ECU detects the error and reduces the fuelling and thus you loose all gains?
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Mine is a 2001 with a CF3 engine and has 3 lanmbda sensors. each sensor is located before each Cat. as long as each sensor is working, you shouldn't get any errors.
 
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Quote:
Originally Posted by alfieblack View Post
From what I understand, you can do that on older 147 engines but not the newer ones? I have read the sensors are in different places. On the newer phase engines the ECU detects the error and reduces the fuelling and thus you loose all gains?
Im running my GTA with no cats and no spacers or minicat spacer things, no MCSF errors so far. Silvervalver suggested the ecu averages the readings over distance, so wait and see for me, but I would have though the ecu would be comparing their readings constantly, so not sure.
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Alfas dont need cat foolers. my GT had all 4 removed and no errors and my 1750 giulietta and no erors
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Ive spoken to a few tuners. They have told me that a cf3 engine will detect the decat and assume that it is over fuelling.

They have said that I need to remap to ignore or at least modify what the sensors are detecting.
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if anything, a decat will be detected by the ecu as UNDER fuelling! The lambda sensor after the cat, under normal conditions, only sees a rich mixture unless the injection has been interrupted...
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As stated before. Seen this on Busso, Twinnie and 1750 where cats are removed and no error is thrown.
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the Lambda Sensors on the CF3 Engine are all before each Cat, so it won't know if the cat is removed or not. i've just had my MOT done a couple of weeks ago and it passed the emissions with no main Cat.
 
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Next year, after April, if the cat is missing it's an instant MOT fail!
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Quote:
Originally Posted by mor1matt View Post
the Lambda Sensors on the CF3 Engine are all before each Cat, so it won't know if the cat is removed or not. i've just had my MOT done a couple of weeks ago and it passed the emissions with no main Cat.
On the CF3 you have lambda, precat, cat, lambda, so if you remove the precats then the secondary lambda sensor may or may not trigger an error, depending how well the car is running anyway and how effective your secondary cat is.

Last edited by Pud237; 14-12-11 at 07:35.
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(Post Link) post #17 of 56 Old 13-12-11 Thread Starter
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effective your secondary lambda sensor is
So I may need to get the sensor reading to be ignored by the ECU by remapping?
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Sorry, I meant how effective your secondary cat is, not lambda sensor. I'll edit my post now.
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Quote:
Originally Posted by mor1matt View Post
the Lambda Sensors on the CF3 Engine are all before each Cat, so it won't know if the cat is removed or not. i've just had my MOT done a couple of weeks ago and it passed the emissions with no main Cat.
Not true.
Last lambda is after main cat on all CF3 engines

Also, after removed ALL cats on CF3 engine, error for Low catalyst efficiency will apper. Seen this myself on 156 2.5V6, and I am sure it will happen on 147 2.0 TS
You have removed only ONE cat (main) and have pre-cats, that's why error do not appear.

Last edited by Boris; 14-12-11 at 11:18.
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So I may need to get the sensor reading to be ignored by the ECU by remapping?
Yes, and this can be done. I have seen in on CF3 2.5 V6
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(Post Link) post #21 of 56 Old 14-12-11 Thread Starter
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You have removed only ONE cat (main) and have pre-cats, that's why error do not appear.
So if i only remove the main cat on my CF3, i wont get any errors?
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Originally Posted by alfieblack View Post
So if i only remove the main cat on my CF3, i wont get any errors?
If your pre-cats are effective (as opposed to old and knackered) then you shouldn't get an error. If you remove all three you will definitely get an error.
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So if i only remove the main cat on my CF3, i wont get any errors?
Yes.
The same is if you remove ONLY precats.

IMHO it is better to remove precats compared to removing main cat. After some time (lets say 100.000 km or more) they are usualy knackered inside, and block exaust gasses flow.
It happened on lots of engines...
Also when efective they generate excesive heat inside engine bay and additionaly warm up the engine.
When I removed the precats, engine is much cooler, CF3 engines get too hot during sporty driving.
I speak from my own experience, I have Oil temperature gauge.
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We have removed all the cats on numerous 147 2.0’s and 156 2.0 as well as 2.5’s with no fault messages afterwards
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Originally Posted by turbonutters View Post
We have removed all the cats on numerous 147 2.0ís and 156 2.0 as well as 2.5ís with no fault messages afterwards
Strange. Maybe ECUs for SA market are mapped different?
Only purpose of second (after cat) lambdas is to monitor front lambdas work and to monitor catalitic efficiency.
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