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Do you need a re-map after De-Cat

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Old 25 February 2009, 12:18 PM
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sammydice
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Default Do you need a re-map after De-Cat

Hi..

Quick question...my car is 2003 STI Type UK

It already has a Afterburner backbox and the resonator section has been replaced.

If I fit a decat\sports cat down pipe and decat centre pipe will the car need to be remapped straight away ? - Hayward ans Scott are literally 5 mins from where I live you see so de-catting should be easy enough - then I can arrange re-map later...

I heard induction kits can make the scooby run lean unless it's remapped but what about de-cats ?

Cheers

Ian
Old 25 February 2009, 12:58 PM
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STI-FINNY
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i had a 04 STI hayward and scott de-catted and it run fine i had the full exhaust system replaced without a re map. + a different air filter and ran fine not 1 problem at all, all you would need is a lamba sensor bypass for the ECU which they should supply / fit to stop throwing up faults.
Old 25 February 2009, 01:21 PM
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ross_wrx
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Originally Posted by STI-FINNY
i had a 04 STI hayward and scott de-catted and it run fine i had the full exhaust system replaced without a re map. + a different air filter and ran fine not 1 problem at all, all you would need is a lamba sensor bypass for the ECU which they should supply / fit to stop throwing up faults.
How do you reverse the Lambda Sensor Bypass? My car is decatted but I would like to replace it with a sports cat so will need the sensor back.

Old 25 February 2009, 01:25 PM
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TonyBurns
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Exclamation

New Age STI's NEED a remap after a decat unless you want to be paying out for an engine rebuild, they boost spike which causes det and this ends up killing the engine.

Tony

Last edited by TonyBurns; 25 February 2009 at 01:26 PM.
Old 25 February 2009, 01:37 PM
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GazTheHat
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Originally Posted by TonyBurns
New Age STI's NEED a remap after a decat unless you want to be paying out for an engine rebuild, they boost spike which causes det and this ends up killing the engine.

Tony
As above. Not worth the risk!

After decatting i had the CEL light on within 5 miles. I kept it below 3k RPM and off boost until the remap the following day.
Old 25 February 2009, 01:43 PM
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Boro
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Never worth the risk with an STi, however WRX's are fine without an urgent remap.
Old 25 February 2009, 01:58 PM
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scooby L
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Originally Posted by TonyBurns
New Age STI's NEED a remap after a decat unless you want to be paying out for an engine rebuild, they boost spike which causes det and this ends up killing the engine.

Tony
+1

Again.... very big gamble....my STI was spiking all over the place, with huge amounts of det (that was with just a de-cat down pipe and keeping the middle cat in)

Not worth the risk imho
Old 25 February 2009, 02:01 PM
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scooby L
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Originally Posted by GazTheHat
As above. Not worth the risk!

After decatting i had the CEL light on within 5 miles. I kept it below 3k RPM and off boost until the remap the following day.
That CEL would have been most likely from the O2 sensor reading not from DET, but better to be safe than sorry...
Old 25 February 2009, 02:23 PM
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GC8
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Yes they do.
Old 25 February 2009, 03:10 PM
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sammydice
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Thank Guys - Thanks exactly what I need to know....
Old 25 February 2009, 03:33 PM
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Jolly Green Monster
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yes needs a map
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