help with a/f ratio gauge

[DSM956]

can anyone help me ? i had a friend of mine install a boost gauge and an a/f gauge..i have an autometer, i'm curious is the led light supposed to go back and forth from lean to rich ? because mine stays in one area where (which is lean) until i accelerate or boost and then it goes right in the middle.i'm a newbie guys so hopefully you all can help answer my question. Like one of my friends has one set up on his maxima and the light is always bouncing back and forth from red to green,til he accelerates then it will go to whichever direction the car is running in,mine doesnt ''bounce back'' its just like off or something. I hope someone can help clear this up for me.

 

[DSM956]

another thing,on the boost gauge..at idle my car is on the vacuum side and it reads 20,is that normal ? the car is boosting the stock 10 psi right now.

 

[sandmstreet3]

well the a/f gauge is really innacurate. if u want a true air fuel ratio, get a wideband oxygen sensor kit. I dont see you running lean on stock boost since our cars run rich from the factory.

and 20hg vaccume is just fine for idle!

 

[DSM956]

thanks bro,im jus curious because i have a check engine light and the car seems to run fine,we hooked up the computer to it and it read air/fuel malfunction. my mechanic suggested it my be the ''air fuel meter'' the idle is off,one sec it idles at 1100 rpms,then it will go down to 800 then back up to 12-1300,any thoughts ?

 

[ColonelOdem]

It kinda sounds like your car is not exiting the warm-up mode because your car should Idle dead on at 750 rpm. It could be your thermostat...I've heard of it being that before, but it coud be many other things as well though...

 

[Oreopride18]

See if a shop can do a check on that engine light code. You're "inaccurate" Air-Fuel ratio gauge is only good for one thing: Telling you if you're O2 sensor is screwed up. Congrats; it's actually doing it's job.

As described, it is supposed to bounce back forth at idle and at normal driving. The fact that it stays red means your O2's are LEAN which is a really bad thing. As inaccurate as it is said to be if you're not getting any green or even orange on normal driving conditions there is a good chance your O2 sensor is dead.

Get the code checked out.

 

[SpoolnTsi]

The A/F ratio gauge is not innacurate! I dont even know why they call it a A/F ratio gauge. It doesnt even read the A/F ratio. If it was it would have numbers on it given you your a/f ratio. Its just a stupid little gauge, with stupid little pretty lights that flow back and forth at idle and cruising. The only time they dont is at WOT. They should just call it a o2 sensor gauge causes thats basically all it does is read the volts. Its a way of determining the a/f ratio, not giving you your a/f ratio. If you want something to read the a/f ratio, get a wideband. Anyway the gauge is accurate for reading the o2 sensor. If you were to hook up a logger and compare it to the gauge you will see what i mean. They get the same results with the voltage. So heres some good info about the o2 sensor so read up. The higher the number, the more rich you are. The lower the number, the more lean you are. Example: 0 volts is lean, 1.0 volts is rich. At idle, the voltage will always be fluctuating back and forth. In general, the o2 signal should cycle between approxamately .2 and .8 volts while idling and cruise when the ECU is in closed loop mode (4000 rpms and below). The higher the RPM, the cycle will be quicker. Once the ECU has switched into open loop mode (high RPM and/or load) the o2 signal will stop cycling and should be in the upper 25% of the range. Once you let off the gas, the o2 should flatline but should pick up right after getting back on the gas. If you have a so called a/f ratio gauge with the pretty lights , thats exactly what it will show you and the logger will give you the same results. So when you go WOT, the o2 should be pegged at a certain number, and the a/f ratio gauge will do the same. 10-1 It should be pegged at rich (green). If it isnt, then the problem more than likely lays within the o2 sensor. This is probably information boilover for you, so what im getting at is...........if the a/f ratio gauge isnt pegged at rich at WOT, then more than likely your problem is the o2 sensor which is how the ecu determines the a/f ratio, hence the CEL air/fuel malfunction. I probably just wasted my time beings how old this thread is but oh well. Hopefully you should have had this problem fixed by now