Hey, I just installed my wideband and have been doing some searching on this forum, from what i have found I am sitting normal, possibly a bit rich tho but this is what I have found.

mods: intake, high flow cat. stock everything else that would control a/f ratios....

A/F ratios:
idle floats around 11
wide open throttle is 10.0
cruising speed is stoich.

The number i am most currious about is WOT, my buddy has a catback in his car and is running 11 at idle and 11 at wide open throttle. He has everything else stock as well.

Is what I am getting good/bad or normal?

Thanks.

 

air pump and ACV disabled?

 

air pump is deleted, but that forces air into the cat, wideband sensor is in my stock rhd downpipe. so i cant see that making a difference... or does it?

 

just researching more about the ACV. I just blocked off the pipe leaving the Air control valve, i did not remove the ACV itself. would it be a good idea to remove the acv and block it off from underneath or will that not make a difference?

 

ok this is a big misconception.. The air pump only puts air into the cat under a narrow set of conditions. The engine has to be warmed up and running at low-medium highway loads.



The air flows into the rear brick (second stage) of the catalytic converter. This is used for HC, CO, and NOx conversion.

Most of the time the air pump puts air right into the exhaust ports. Some of that air blows back into the intake side due to overlap of the intake and exhaust stroke, leaning out the mixture inside the engine. This reduces misfire and increases combustion stability under these port air conditions.



The rest of the air pump air goes into the exhaust before it reaches the catalyst. During port air mode oxidation (HC and CO conversion) occurs mostly. This is because these old rotaries have low NOx output. THey need to run a richer mixture for idle stability, due to the aforementioned overlap between the intake and exhaust stroke, and richer mixtures produce low NOx. Old piston engines from the 70s were similar in a lot of ways. A Renesis rotary engine only uses the air pump during cold start for emissions, like a lot of newer piston engines.

None of this really applies to WOT--the air pump turns off under those conditions. Clearly, it's a pain in the *** to have all that emissions crap around. That doesn't mean it has no effect on driveability or idle quality though.

 

If you don't have any kind of boost leaks or other problems, I would avoid digging in there if you can. There's a chance of something going wrong when you pull stuff apart.

 

redrhdrx7,
I use targets something like this with the excel program listed with arghx and Chuck's notes.
Barry

 

im just curious to know if 10 is a good a/f at wide open throttle for a stock fd computer or is there something that is causing me to run more rich than normal? thanks

 

11 afr sounds rich to me, I've got a completely stock setup with a jdm downpipe (no precat). WB is installed in the DP before the cat. Cold startup idle is 11.5:1, but by the time it's warmed up I see approx 13.0:1, occasionally as lean as 13.5:1. Oddly, I just did a pre-test for smog, and failed due to high HC's, which the smog guy said was because i was running too rich.

Beautiful FD btw, love the wheels!!

 

that's normal... it was tuned that way from the factory to keep exhaust temperatures down

 

DOHC Vobra - thanks for the compliments. appearance is number one for me, but i still want to have the power to back up the looks do you actually get 13.0:1 afr at wide open throttle right through your whole power band? to me that sounds quite lean... I am very new to a/f and tuning but im reading a ton and hoping to learn as much as I can. Someday when i build up the courage I will be ready for a power fc and start modding. As of now, reliability mods, and i want to run safely with a few bolt ons.

If 10.0:1 a/f is normal well then thats perfect if that is where it is supposed to be. anyone else have comments on what their stock rx7 runs for air fuel at wide open throttle?

 

Sorry, should have clarified, 13.0 was referring to warmed up idle only (I'm still breaking in my rebuild, so haven't seen where it runs at WOT yet). 10:1 sounds reasonable at WOT under boost, but I'm definitely no expert when it comes to rotary tuning. 11.0:1 still sounds like it might be idling a bit rich though.

 

ok. i really dont care what it does at idle... i hear all readings are not very accurate at idel... wide open throttle is all i am really concerned about.

 

Your numbers sounds similar to what my wideband was reading with a stock ECU and aftermarket downpipe. 14-15AFR when cruising, about 10.0-10.5 at WOT, and about 11.0-12.0 at idle when the air pump was disconnected. With the air pump connected and the ACV working, the wideband displayed something closer to 16-17 AFR at idle.

 

good to hear that other rx7's have similar numbers... blowing up a second motor this summer is my worst nightmare right now :S