grantd

So I want to install a AFM problem is where to install the wideband O2 sensor.

Basically there’s just no room on my aftermarket Fab Speed headers. Has anybody done this an if so where did you install the Oxygen sensor. I am running K Lambda CIS so I was thinking perhaps I could just remove the existing O2 sensor and install the wideband sensor in its place.

Suggestions and advice please.

Spartan

I put one on the cat bypass pipe

Metal Guru

Anywhere behind the turbo is ok but not within 6 inches of the exit.
Mine's in the tailpiece behind where a bypass pipe would be, except my muffler's in that position.

grantd

Ended up using a wideband LM2 and the Exhaust clamp.

At the cruise my AFR readings were around 14.7 and on full boost around 10 - 10.5 which is really quite rich and therefore very safe.

I also got a hold off a CIS pressure tester and my pressure tests where all as per specification. Not bad for a 20 year old car that has never had its WUR replaced.

H2O LOL

Jinxed yourself. Get ready for a adj WUR.

cobalt

Interesting I need to double check but I run around 14.7 while cruising but only dip to around 11 - 11.5 under full boost.

BTW great color do you have any pics of your tail it seems to be painted and not the traditional rubber. Is it a turbo S style?

grantd

Photo of rear end..its all standard

Metal Guru

How much boost are you running and what is your afr at boost onset (approximately 3200-3500 rpm if you have headers, 4000 rpm if you don't) and at 6000 rpm? It should lean out some toward the higher engine speed.
An afr of 10 - 10.5 is an indication that you need to have your wur rebuilt. Wurs tend to go pig rich as they go bad. Eventually the diaphragm fails, leaks gasoline into the overflow in the air cleaner housing and your car won't run at all. You are leaving horsepower on the table at those readings. You ideally want to be at 11.5 at low speed and you will gradually lean out at the top end (it's an unfortunate characteristic of CIS) to 12.5 or thereabout.
I recommend that you send your wur to Brain Leask and have it rebuilt (he will make it adjustable at the same time). Brian can also provide you with a heavier diaphragm if you run boost higher than stock.
With my Leask wur I'm at the high end of the range of factory spec for cold control pressure (cp), nominal for warm cp and low end for enrichment cp. This is yielding afr's of 14.5 at cruise, 11.5 at boost onset and 12.6 at max engine speed. I'm running .85 bar of boost. I had to re-set system pressure to the low end of the spec to gain adjustability.
Hope this helps.

speednme

Everything I have read(from the mfg of afr meters plus what I have done on my own 930) is the correct location for proper o2 location is after the turbo.

Metal Guru

+1
I read somewhere that only the narrow band O2 sensor can be successfully installed immediately after the turbo.
The only concern I would have with the tailpipe clamp is inaccurate readings at idle from reversion.