Hey all,

WHat are some symptoms for a bad O2 sensor. For the last couple of days my CEL has been coming on and off. I checked it once when it was on and it was a system too lean code. I know that I have enough fuel because my A/F readings are normal. Also the CEL usually comes on at startup and not while driving. My Autometer A/F gauge doesnt bounce back and forth like it used to. Also I was at a traffic light today and my car almost stalled for no apparent reason. I was running the A/C but that I dont think has anything to do with it.

Right now my idle is around 800-850 RPM, is this normal?

Corbin,
Right now I have your digital O2 sensor hooked up and my autometer one. Yours is tapped into the ECU as per the instructions and the autometer one is tapped right to the O2 sensor. Will this cause my problems as the current has to be shared by two meters. Also can you please email me with tips how to tune with your digital gauge as the help file on the main mods page is down.

Sorry about length. Thanks for all your help.

Thomas.

Also I was at a traffic light
>today and my car almost stalled for no apparent reason. I
>was running the A/C but that I dont think has anything to do
>with it.

If one of the O2 wires for one of your gauges grounded against the chassis, it would cause the car to nearly die and put up a CEL. I used bad wire on my original homemade bargraph A/F and it grounded against the chassis...causing the symptoms I described.

>
>Right now my idle is around 800-850 RPM, is this normal?

Nothing odd about that. I go from 650 to 800 at idle (AT) depending on whats going on.

>
>Corbin,
>Right now I have your digital O2 sensor hooked up and my
>autometer one. Yours is tapped into the ECU as per the
>instructions and the autometer one is tapped right to the O2
>sensor. Will this cause my problems as the current has to
>be shared by two meters. Also can you please email me with
>tips how to tune with your digital gauge as the help file on
>the main mods page is down.

I suggest that you remove the Autometer A/F gauge. I know my guage will work well by itself, but I can't guarantee that it will work well when used with the Autometer. To test the gauge installation, cruise up to 40-50 mph and quickly let off the gas. If you do it right, the A/F volts should dip near zero for a second. Anything from -0.009 to +0.009 is ok. If it is out of those bounds, you should check your hookup. When you first start the car, the voltage should start around .15 and slowly climb up to .7-.8 and then start cycling. Expect it to cycle from .2 to .8 while cruising at less than around 80% throttle. The ECU is in closed loop mode and using the O2 sensor to figure how much fuel to inject. When it stops cycling and sticks at one number, the ECU has gone from closed loop mode to open loop mode. It will do this near WOT. This is what you read to tune. It can be anywhere from .9 to 1V. anything right around .9V is close to stoic. .92 and above should be rich. .89 and below should be lean. I usually see .91V when my car is running well at full boost with good EGT (around 1500F). When it hits .92V+, my EGTs will be lower (1480-1400F).

Corbin

'95 ESI-T
HRC+FMIC+ETC...



Gimme fuel...Gimme fire...Gimme that which I desire

so what does it mean when the car stays in open loop at everything except idle?

lately, the car will remain in open loop nearly the entire time im driving, even cruising, cept idle. then it cycles. also my gas mileage has been horrible (16.7mpg on my latest fill-up, i do have a heavy right foot, but damn... last fill up was around 15.5, same deal with staying in open loop).

last i posted this, i got a couple bad map sensor suggestions...

any ideas?

no notiecable power loss at WOT, hell played with a 996 carrera tonight, and he was just barely inching me up to 105...

95 automatic, hrc (equiv to stage 2), sfmu, 30lb injectors, bunch of other shit that i dont think are related (could be tho, complete list @ http://www.asog.net/phantom )

If you have an original O2, you might blame it. If you've replaced your O2, I'd bet its something else. What fuel pressure are you running with those 315's? Maybe you are dumping too much fuel in and the ECU can't really control it. I know I had to lower my fuel pressures down below what I expected when I put my domestic injectors in. I don't know if its the coil resistance or pintle design, but I ran a good bit richer than I expected.


Corbin

'95 ESI-T
HRC+FMIC+ETC...



Gimme fuel...Gimme fire...Gimme that which I desire

i run ~25-27psi at idle, and ~62psi @ 8lbs. i dont have a SAFC.

it didnt always stay in open loop tho, so i suspect its something new. i was thinking o2, but some people here suggested map sensor might be suspect as well

edit-
oh, and yes, it is the original o2 sensor

a/f gauge not operating correctly at WOT. HORRIBLE gas mileage. Backfiring. (too much gas) When the ECU doesnt get a normal reading from the o2 sensor, it will in return just dump fuel to be safe. Hence the bad fuel mileage and backfiring. Replace it or it will destroy your plugs as well. Bad o2 sensors are a symptom of running WAY rich anyways so fix that as well. Good luck.

hmm, when i let off the gas my gauge reads anywhere from .02x to .05x. and my WOT always goes over 1.0 volts and then drops down to about .96 to .97. i guess im running hella rich

Joe...Try accelerating hard and then letting off the gas completely. See how low you can get it. If you really can't get it near zero, we'll have to do some investigation.


Corbin

'95 ESI-T
HRC+FMIC+ETC...



Gimme fuel...Gimme fire...Gimme that which I desire