Thread: afr questions?

i installed a zeitronix wideband a couple days ago and i was dataloging it yesterday and notice that my afr reeds 21.00 afr at idel and when i'm cruising around 3k rpm but when i'm at WOT it stays between 11.2 and 11.5 my concern is why does my afr read 21.00 afr at idel and while i'm driving normal?

i'm running a t3/t4 turbo,38mm external wastgate,z32maf,525cc injectors,walbro 255 fuel pump, aeromotive fpr, and i have a calum basic map for that set-up.

Are you running closed loop or open loop at idle and cruise? If closed, you might have an issue with O2 sensor.

Or you might have a calibration problem with your wideband.

It depends on if you have a leak near the wideband. Also if the 02 feed back is off then you would have to program the right a/f. Since you have a basic have fun burning chips.

I guess I'm not clear either. Do you mean that when you let off the gas while cruising (as in engine braking) it jumps to lean? Or, do you mean actually putting in the clutch and letting the RPM's drop. I am assuming you mean the first.

Mine also jumps incredibly lean when I engine brake, but I think it's just the nature of the engine. You are running at 3k RPMs, but the ECU reads zero throttle, so it barley throws in any fuel. I think it may have something to do with the method by which widebands measure the post combustion gas chemical concentration (of CO?). I'm not sure if that quite makes sense or not, but I have always assumed that it was normal for that to happen (mine has always). In any case, I've been running that way forever and ever, and it never causes a problem!

EDIT: Oohhh you meant like, cruising while on the gas? Man I'm stupid. Definitely re-calibrate it to make sure it's working properly and then see if it says the same thing.

While cruising around mine reads 14.7. Under deceleration if obviously goes lean. Idle is around 14.7-15.1. If you are idling at 21, the car most run like ****. What is your vacuum @ idle?

I wouldn't worry too much about it. I see afr above 17:1 at idle as well. The car still runs good. It should be around stoic, but if you have bigger injectors it can be a little difficult to get that number.

I think the problem could be the o2 sensor, but I don't think your car would idle at that lean of a mixture. Have you checked for leaks? I know I have one, but I can't find it yet.

my car is actually running strong and healthy, i just pulled a 12.5 @ 111mph on the 1/4 without any problem, my vacuum is at -15 in idle.

i see 17-18:1 also no problems

i've been driving my car like these over a year now and i haven't seen r had any major problems other than the normal boost leaks once in a while. i had never checked my afr # for that long of a time until recently when i installed the zeitronix wideband i got and thats when i saw those afr #'s.

i'm thinking that my o2 sensor went bad, i have an exhaust leak not sure were exactly but its after the o2 sensor and the afr sensor, would that couse me to get those kind of readings?

Letting off the gas completely and coasting in gear will shoot your AFR's up cause the injectors turn completely off when this happens.