High Flow Cat

[Kelpie]

Hi guys, any idea why would a change from stock cat to high flow cat cause the engine check light to turn on when running in excess of 120Km/h? One way to overcome this is to install a resistor. I wanted to find out whether this is a common issue with high flow cat. Thanks.

 

Regards,

[Dynaway]

the stock catalytic convertor have a fixed mass flow rate that is designed/selected for the car by the manufacturer in order to meet the emission standards or curb the emission output.

 

changing tat may have cause the flow rate, reading setting changed from the stock... might have been out of the working range of the ECU reading tat causes the light to be on.

[Kelpie]

the stock catalytic convertor have a fixed mass flow rate that is designed/selected for the car by the manufacturer in order to meet the emission standards or curb the emission output.

 

changing tat may have cause the flow rate, reading setting changed from the stock... might have been out of the working range of the ECU reading tat causes the light to be on.

 

So out of working range means it is harmless since it is a "false" reporting?

 

Thanks.

 

Regards,

[Infernose]

some modern cars have 2 O2 sensors in the exhaust, 1 after header, and 1 after cat. if you modify the cat, the flowrate is affected. the reading picked up by the 2nd O2 sensor might differ from the range that is expected by the ECU, and hence the CEL. using a resistor on the 2nd 02 sensor will overcome the problem, but how the performance and safety is affect, i don't know. and i think the ecu might not switch properly between close/open loop?

 

in the event a CEL is triggered by the ECU, it might revert to very conservative settings, may result in compromised performance/fuel comsumption. normally this means the AF ratio will be rich, to prevent engine damage.

Edited August 27, 2007 by Infernose

[Kelpie]

Thanks for the explanation. Strange, it works the reverse way, the fuel consumption is actually reduced with the CEL on. This is an unexpected result since no aftermarket ECU nor piggy-back is used. To monitor further.

 

Regards,

[Dynaway]

they should logically run lean as the ECU has revert back to minimal setting when the CEL came on...

 

this explains why u getting better fuel consumption....

 

with the CEL on, u'll not be operating in optimal range...

[Kelpie]

No noticable impact on performance leh. Yet to test the high-end at NS highway.

 

Regards,

[Xiaogary]

It depends on situation. If exhaust harmful gas is too much at the 2nd sensor, then it will light up the light. Depends on make. Like for chevrolet, it only light up, but it doesnt affect the fuel supply. It doesnt run leaner.

 

In fact when the exhaust temp is too high detected by 1st sensor, it will run more rich to cool down the internal more.

[Kelpie]

I think the ECU would learn and then gradually neutralize the effect and is now back to the usual consumption pattern.

 

Regards,

[Vicma]

Hi,Kelpie.

 

Change to HFC on my swift,check light came on three time

speed 70 to 80 ,have not tried 120 at NS.Reset it by remove

batt terminal.Can tell me where to install resistor & how munch?

 

THKS

[Rhys11]

hi,need some info regarding eliminating the cel light. its for cars that r decat. Is there a mechanical o2 simulator for sale in our car shops here, read in other overseas forums and it seems too work n is popular. its a originally a spark plug non fouler, modified into tis device that can be placed between our o2 sensors tats after the cat, lengthening the // distance that the sensor would read the exhaust fumes from. tis would enable the exhausts to not read the exhaust fumes as so high readings, thus the cel light would not come on.

 

read it in a s2000 forum, seems like 99% of them r successful,

http://www.s2ki.com/forums/index.php?showt...=simulator&st=0

 

any advise? anyone tried? thanks, btw, how to start a thread har, seems like cannot find the option to.

[Kelpie]

I don't know whether resistors are car specific. I've yet to get one as the WS advised me no stock, so have to wait. Usually 100plus for one. I don't know the exact amount yet.

 

Regards,

[Vicma]

Thks Bro,

 

Can PM me when stock arrive & price with installation

[Msimax]

hi guys changed to a high flow cat on 10/10 & went up NSH on 12/10. Cat's internal ceramic has all been shattered. assume e exhaust gas could be too hot for e cat to handle or e workers dropped e cat onto e ground b4 fixing to e mid pipe, coz i don't recall having hit anything at slopes or humps.

 

already checked w FK stainless steel ones coming in only in Nov, kind of urgent to replace e cat to avoid christmas lights on dash.

 

anyone happen to know which wkshop has an avail stainless steel cat?

Edited October 13, 2008 by Msimax