Cat advice for MB2 with downstream O2 sensor

[EdGasket]

Hi, my MB2 Civic which is OBD2, has an exhaust rattle which I believe is internal to the cat; I notice it when the engine is revved, pulling away etc. (Have checked heatshields which seem OK). The car has also thrown a P0420 (cat efficiency) code and if I clear it it usually comes back within 50 miles.

 

The MoT is due next month so I am not doing anything before and will see what the emissions are like; but if I do need to replace the cat, are the cheap cats on eBay and from EuroCarParts for about £60 any good e.g. HA8002? Will they do the job and prevent the check light coming back or do I need to spend more on a better cat?

 

e.g.

http://www.ebay.co.uk/itm/CATALYTIC-CONVERTER-CAT-FOR-HONDA-CIVIC-1-4-1996-1998-HA8002-/331682519400?hash=item4d39d19968:g:O24AAOSw14xWH98N

 

Also how do I access the connector and wiring for the downstream O2 sensor; is it by removing the centre console? Is that straightforward or a pain?

[Gel]

Hi and welcome to Civic5 ,  I have symptoms identical to yours bar the rattle....friends familiar with Honda's tell me to avoid non OEM CAT's so what I intend doing for the MOT is this :

 

Knock the CEL (Check engine light) off and reset the fuel values before I present my MB2 1.4 for MOT

 

Once the MOT is done and dusted I'll fit a Lambda spacer (a spacer keeps the sensor away from the bad emissions)......

 

The spacer could save me forking out for a genuine CAT and/or downstream Lambda sensor (they do tend to get sluggish over the years)

 

If you need us to elaborate just shout.

[EdGasket]

Thanks I know about the spacer/defouler trick with the lambda sensor. OEM cat sounds £££s; will it make much difference on a 1.4; not interested in performance; just cheap motoring.

 

How do you 'reset the fuel values' and what are they? I have an OBD2 reader which will reset the CEL.

 

Also any advice on reaching the downstream O2 sensor to fit the spacer and unhooking the wiring which seems to go straight up through the floor?  As a spacer alternative, you can fit a simple filter - resistor and capacitor once you have got to the wiring.

[Gel]

Easy peasy instructions here :

 

http://civic5.com/forum/topic/8084-how-toreset-your-ecu-honda-civic-mambmc/

 

I can't help with locating the wiring harness but I would be interested in hearing all about the ECU cheat method.

[EdGasket]

So why would you need to reset the ecu? Could make emissions better or worse couldn't it depending on how the ecu reads the sensors. Also is that 100% right about just letting it idle because then the ecu is only going to see 'idle' values? Surely you should take it on a normal drive so the ecu can learn the full range of values from each sensor; Just my thoughts.

 

ECU cheat method for downstream O2 sensor is shown in this video:

 

 

It's just a low pass filter to stabilise the second O2 sensor output so it doesn't track the upstream sensor (indicating cat not doing much) and avoid a P0420 error. Has the advantage of not having to remove a rusted in O2 sensor but you will have to break into the wiring at some point.

[Gel]

When your car is afflicted by a CEL the ECU automatically reverts to default fuel settings therefore it is prudent to reset the fuel values.

 

Once you've reset the ECU....re-start your car and take it for a drive whilst it's in learn mode........job done .

 

Thanks for linking us to the electronic dodge.....I'll view the details later on.

 

Good luck with the MOT albeit your car should pass the emissions test without issue.