Bouncy A/F Ratio

[4felix20]

Hey guys, I've been wondering about this for a while. During normal driving, my A/F gauge is back and forth through lean and rich. it's not a problem under boost though, since it's tuned to run a little rich which is reflected on the gauge under boost. But just normal driving, she's bouncing back and forth.

I've thought about it for a while and i think it could be a number of small problems, but i'm just wondering if any of you guys have had a similar experience, and if maybe any of you would be able to help me pinpoint this problem..

[TrunkMonkey]

i'm bumping this so no one overlooks this amoung all the old threads that are being brought up.

-demetrius

[WDRacing]

What type of AF gauge and sensor are you using? Is it a wideband or narrow band?

[4felix20]

thanks demetrius.WDR, i'm thinking it's a narrow band. the thing is, the previous owner installed it so i'm not too sure.

also, sometimes the check engine light flashes when the gauge is bouncing into lean. not all the time though. usually, just when i don't give her time to warm up. it's kind of wierd, but when the CEL does happen to flash, the gauge bouncing into lean and the CEL are in unison.

[Charlie240sxt]

What do you need to have a A/F gauge that works well? i heard if you use a stock O2 it dont work well. So get a wide band??

[Turbogixxer]

i'm thinking it's a narrow band. the thing is, the previous owner installed it so i'm not too sure.

It is most likely a narrow band. Wide band will tell you the excat A/f, not just rich/lean.

Hey guys, I've been wondering about this for a while. During normal driving, my A/F gauge is back and forth through lean and rich. it's not a problem under boost though, since it's tuned to run a little rich which is reflected on the gauge under boost. But just normal driving, she's bouncing back and forth.

To question your question correctly, I have to explain what closed and open loop(s) are.

Open loop is when the ECU (ECM, samething) runs on pre-programed maps (fuel and timing). This programed in to the ECU from the factory (or when tuned). The engine runs on open loop when the car is warming up (02 sensor, mainly) and when you for Wide Open Throttle (WOT).

Now for closed loop. Closed loop is when the ECU takes input(s) from the engines sensors (mainly the 02). It uses this info to run close to the Stoichiometric ratio (14.7 for gas). A narrow band 02 can not read excat a/f ratio, so the ECU has to jump from rich to lean and over again to find the amount of fuel that is closest to 14.7 a/f. Thats why your a/f jumps at idle and light loads and not at WOT.

also, sometimes the check engine light flashes when the gauge is bouncing into lean. not all the time though. usually, just when i don't give her time to warm up. it's kind of wierd, but when the CEL does happen to flash, the gauge bouncing into lean and the CEL are in unison.

Check what the code is. It is probably O2 code.

[4felix20]

makes pretty good sense. thanks turbogixxer...you're the man.

[WDRacing]

He's exactly correct, you can't really use a narrow band O2 meter for anything except maybe idle tuning. The rest is useless. Every narrow band I've seen installed bounced the same way yours does.

[4felix20]

i love you guys. plain and simple. =)