Cobra check engine

trebot

New Member
Joined
Jun 17, 2022
Messages
5
Location
Lexington MI
Have '98 Cobra, new to me. She throws a "check engine" every 100 miles. MY scanner (Konnwei KW808), says " Catalyst System Efficiency below threshold Bank 2". Car has No Cat exhaust and K&N air filter. Car runs fine.
What is the scanner telling me? What spark plug should I use for normal driving?
Any help appreciated. Thanks, Kurt
 

robvas

Well-Known Member
Established Member
Joined
Sep 8, 2020
Messages
1,315
Location
MI
Try Amazon or just a Google search. Looks like they are out of stock on eBay
 

shurur

Well-Known Member
Established Member
Joined
Jan 2, 2011
Messages
3,760
Location
Lutz, FL
Yup..it is probably an S2 (sensor after the cats) that looks at the cat efficiency.

S1 is sensor at/before the cat is used by the engine management.

If you can't find an eliminator, there are ( used to be) sites that show how to make your own.

Maybe the EPA is shutting down the sale of these things...dunno.

You should have a p code for this as well.
It gives you something specific. It could be wiring, like an open....or even a dirty MAF.

Pick up a BAFX OBD2 Bluetooth interface and load the Torque Pro app on your phone to get code reads.
 
Last edited:

98 svt

Well-Known Member
Established Member
Premium Member
Joined
May 16, 2005
Messages
23,961
Location
Massachoooosetts
Yeah, pretty sure those MIL (Malfunction Indicator Light) eliminators are hard to find these days.


Only other options are a tune, add cats, or try to use the spark plug non-foulers and see if it works. I've always been curious about them working on our cars.
 

shurur

Well-Known Member
Established Member
Joined
Jan 2, 2011
Messages
3,760
Location
Lutz, FL
The s2 o2 sensors needs a delayed pulse of .5v falling off to 0v, that is delayed a bit after the s1 o2 sensor.
I think that is all a mil eliminator is doing.
It holds a pulse that delays a bit after the s1, and makes the ecu think that the "cat" is holding o2 for a time. That mil elimininator is "the cat."

The o2 extender gives the sensor a delay as well because it is sniffing from further away and hides the lower o2 holding efficiency of a failing cat, by delaying that pulse and making it look better to the ecu.

If you reset the fault, it just shows every 60-100 miles or whatever interval is in the tune..that's why it keeps coming back.

I have the same crap going on on my audi right now..specifically a p0140- no activity.

It can be a open wire, bad o2 or dirty MAF. I am suspecting my MAF, because everything else looks fine and the o2 sensor is new...twice..

But Op's problem seems like something that was created by removing cat and never got fixed....unless the problem is on one side only, as he may already have mil eliminators. I think the s2 o2 sensor and the MAF are somehow linked in the tune of most cars.

Youtube has a ton of info on o2 sensors, with oscilloscope patterns to watch.
 
Last edited:

adammdennis11

Active Member
Established Member
Joined
May 2, 2014
Messages
98
Location
Tampa
I like NGK plugs
Have '98 Cobra, new to me. She throws a "check engine" every 100 miles. MY scanner (Konnwei KW808), says " Catalyst System Efficiency below threshold Bank 2". Car has No Cat exhaust and K&N air filter. Car runs fine.
What is the scanner telling me? What spark plug should I use for normal driving?
Any help appreciated. Thanks, Kurt
Like they said, mil eliminator, I like NGK for plugs
 

Users who are viewing this thread



Top