I am in the process of having an O2 sensor installed on my 85 GSL (12 a carb'd). I am going to have a hole drilled in the manifold about the same place the GSLSE has it's.

I was wondering if anyone else has done this and can give me any tips on the O2 sensor best for the 7? I don't want to choose a style that will foul easy. I was going to use the Bosch GSL-SE generic for the 85 for 24 bucks.

Anways, my goal is to give myself a better idea of where my carbs at when adjusting idle mixture. I want a way to be able to adjust my carb at home with out having to pay a mechanic with an exhaust probe 50 bucks each time to look at it. I figure if I can adjust the carb so that I am at the stoichometric range then I can eliminate some of my backfires and engine fluctuations.

Also, it will give me an idea of where the car is running at cruise. I get extremely bad gas mileage compared to my 84 stock and the O2 sensor should let me know how far I am out of stoich.

 

i'll add some more questions

does the sensor have to be placed before or after the first cat?

and does a rotary have to run any richer or leaner than a piston engine? so if something like a vdo gauge was used would the area for the right mixture for piston engine be the same for the rotary?

 

As long as the O2 sensor is compatable with the gauge your going to use it doesn't matter which on you use. The sensor will foul out as fast as you put bad gas in your car. Also as a rule of thumb, you should use a vacuum gauge to adjust you idle mixture.

 

Place the sensor before the cats' if you have a header, place the sensor in the colector, or just go with the same area the SE sensor is in. Rotary engines tend to waste more hydrocarbons so, as far as I know, it will show up as running rich.

 

Never heard of that, what kind of vaccum reading should I be looking for? And can I take a reading from one of the vaccum nipples on the carb spacer? Thanks. -George

 

The general rule is to get the highest reading. You should try to use port vacuum, but anywhere should be fine.

 

Some cars have them before and aft of the cat so they can test the cats effectiveness. Usually, the O2 sensor is placed as close the the engine as possible so it can get as hot as possible. The GSL-SE has it placed right in the manifold just before the flange.

I was considering using a vacuum guage to adjust my idle but I am not sure if it's accurate enough. Usually, you lower the mixture until the vacuum drops. Then you turn back a 1/4 turn. Then you adjust your idle until the car hits 750. Then you go back and repeat these steps until reconverge on the right settings.

But the Haynes says you need to get the CO below .10 %. I don't have any way of getting close to this without an exhaust analyser.


What do you think is the best way to tune the carb?

 

I'm feeling really dense right now, but with my emissions removed the only vaccum sources I can think of are on the spacer, and the brake booster line. Where would I hook the gauge for port vaccum? Thanks for the answers sofar.

 

sorry guys, now im getting confused here..

whats with this vacume to change the mixture?? is something u can buy/make to adapt to the carb to change the mixture without using the screw??

and, the seonsor is electrical or mechanical or neither??

 

I have been told and read many articles that the best place to put the 02 sensor is 24" from the exhaust ports.

Just thought people should know.

-Error402

 

Actually its funny, I was thinking about putting a vacuum gauge in my car the other day, and I was wondering if I could use one of the spots on the carb space as well...I odnt see why not, which is why Im asking .

~T.J.