Throttle body, O2sensor, and a/f questions!!
 

ok, i have some questions, maybe someone can help me out. first off, i have dont the throttle body mod, and while I was in there I noticed that the secondary throttle plates open just slightly after the primary one does. Is there any reason that I shouldnt make all 3 open at the same time? seems like it would have better throttle response that way.

on to the o2 sensor, how do i check my a/f ratio using a volt meter? as in, where do I hook the volt meter up too?

3rdly, I have hooked up a a/f gauge, but it only reads when the rpms drop to about 400rpm, it picks up about 2 bars of lean. the whole rest of the time when i am driving it picks up nothing. all the connections are good, and have been soldered. the ground is good too. any idea why it would do this? I hooked up the wire that goes to the o2 sensor to get a reading right before the connector that leads into the wiring harness. the directions say to hook it up after the connector but i see no reason why that is neccisary and why it wouldnt work how i have it set up. maybe i am wrong.

please help me!!!

Well, don't know about the others but is your 02 sensor new, if so which one did you buy? The mazda ones are crap and may not work with the gauge. Bosch's are good. Hope this helps

The throttle body (TB) mod, a.k.a. gutting the TB, will increase throttle response - sort of. The secondary plates slow the initial rush of air when you floor-it. Without the plates, you may notice a slight (usually unnoticable) stumble if you really hit it quickly. The TB mod also gets rid of pesky thermowax problems.

About your O2 sensor and A/F gauge: If you are using the $28 sensor from the parts store it is useless for monitoring A/F outside a very narrow band. For a good explanation of wideband O2 sensing, visit MoTeC's site, or M&W Ignitions site. You need a unit with an NTK/NGK UEGO sensor and proper controller unit if you are tuning a modified engine. The Bosch LSM-11 sensor is ok, but is not trusted as much as the UEGO's.

Hope this helps.
Steve C