Just wanted to check on something. I just got an autometer air fuel guage installed on my 93. When I drive it goes from extremely lean (at idle) or even non existant on the guage to extremely rich even under 3/4 throtle. Is this normal with a downpipe and cold air intake?

Thanks in advance

 

Yes thats fairly normal - Rotaries like significantly richer than Stochiometric A/F ratios.

If your O2 sensor is more than 24k miles old I would recomend replacing it. you will get better readings (and better milage) with a new sensor

 

IMO, the Autometer A/F gauge is not going to tell you much, good if you like lights, but worthless for actual tuning. The key is making sure that you are rich enough under load. The Autometer canNOT differentiate between something around 12.5-13.0 vs. 11.5. Big difference as far as the rotary is concerned.

The stock O2 sensor (and the close loop control) uses a narrow band O2, which is good at measuring stoichiometries close to 14.7:1.

To get anything useful, you need to get a wideband sensor, controller, etc.

 

Yeah, the autometer a/f gauges reads too wide of a range to really give you any meaningful information. That is why I had mine modifed to read a narrower range - during WOT only, when you really need to know your a/f the most.

http://www.gadgetseller.com/gauges/index.htm

Read thier FAQ.

Speaking of which, I'm selling my black faced gauge so I can get a white faced version to match my new NR white faced gauges. If anybody is interested, please e-mail.

 

i have the greddy one that comes with the high band o2 it reads in a numbers. and since the 02 connects directly into the gauge and it is a 4wire high band o2 you get a better reading. i sell them at my shop for 275.