O2 Sensor reason for richness???

[zook]

Hey, so my fuels trims are like, 81 % across the board. My O2 sensor voltage is staying at 2.08 V. Is this the most likely cause for me running so rich?? Do I want to strive for 100 %, and how high is TOO high? Just so I know when I start playing around. Other than bad gas milage (which I figure it's not all that great) what else would this richness be causing? What will I gain from leaning it out now.

THanks, kinda new to this, I used to be a Samurai guy, there's about 2 sensors on those things!!!

 

[DragGSX]

first off you should start by telling us what you have done to your car so far.

 

[zook]

not a thing. I haven't had the money to do anything to it yet I just got my cable for the Palm last night, and I ran MMCD. It's pretty cool But now I know I am running rich.

Thanks

 

[91gsxboosted]

Hey, so my fuels trims are like, 81 % across the board. My O2 sensor voltage is staying at 2.08 V. Is this the most likely cause for me running so rich?? Do I want to strive for 100 %, and how high is TOO high? Just so I know when I start playing around. Other than bad gas milage (which I figure it's not all that great) what else would this richness be causing? What will I gain from leaning it out now.

THanks, kinda new to this, I used to be a Samurai guy, there's about 2 sensors on those things!!!

well I think that your o2 sensor may be defective because it should not go over 1 volt. optimum voltage is between .6-.7, and at full throttle maybe a little higher so you dont have a chance of detonation.
-joey

 

[missouri_dsm]

change your o2 sensor.

 

[zook]

Ya, I thought so, I just wanted to confirm. So is 100 % what I want.

Thanks!

 

[missouri_dsm]

yes %100 is perfect. although you probably wont see %100 on every trim they should be close. Your high trim will be a little rich on a stock ecu so it is more safe.

 

[steve]

Hey, so my fuels trims are like, 81 % across the board. My O2 sensor voltage is staying at 2.08 V.

Make sure your looking at the right O2 sensor in MMCd. It's actually the O2-R that you want.

If you are looking at the right one and your O2 voltage is really 2.08v then either the sensor/sensor wiring has problems or your ECU does.

Steve

 

[NixHex]

shouldnt the O2 sensor give a reading that switches back and forth around .5 V?

generally less then .5v is lean and more than .5v is rich and it should go up and down as the ecu corrects i think?

if im wrong do corect me.

 

[knighteclipse1]

Hey, so my fuels trims are like, 81 % across the board. My O2 sensor voltage is staying at 2.08 V. Is this the most likely cause for me running so rich?? Do I want to strive for 100 %, and how high is TOO high? Just so I know when I start playing around. Other than bad gas milage (which I figure it's not all that great) what else would this richness be causing? What will I gain from leaning it out now.

THanks, kinda new to this, I used to be a Samurai guy, there's about 2 sensors on those things!!!

New to this?? and your a registered member?? hhmm...is it throwing any codes? I would assume that its possibly the O2 sensor, is it possible it is a bad MAS too. check your plugs, see if they are fouled, smoke? gas mileage? tell us alittle more here...

 

[steve]

Shouldn't the O2 sensor give a reading that switches back and forth around .5 V? Generally less then .5v is lean and more than .5v is rich and it should go up and down as the ecu corrects.

Yes but.

It's actually the ECU in closed loop adjusting (not really correcting) the fuel that causes the O2 sensor to switch. The ECU tracks how much of a change it has to make to get the sensor to switch in the variable FT02 in MMCd. Unlike the other fuel trims where number < 100 are rich and > are lean the FT02 values get less as the ECU leans out the AFR and high as it richens it.

Over time the ECU averages the corrections it gets from the O2 feedback trim into the fuel trims and you see the FTO2 move back to even swings on either side of 100 as long as the other fuel trims have the range to correct.

With an O2 sensor reading 2+ volts the ECU isn't going to even enter close loop and should be throwing a CEL, but long term 1G owners know that the ECU rarely throws a O2 CEL even with a dead sensor.

Steve

 

[zook]

Ok, looking at my log here.... so I actually want to look at O2R on a 1G??? I thought I read somewhere else that on a 1G and MMCD you want to look at O2-F?? My O2R is switching between .18 and .74 Volts. Which then it would be working. Is it normal for O2F to be reading 2.08V on a 1G since it only has one sensor??

knighteclipse1: New as in playing around with the engine on these things. I've had a DSM for almost a year, but it was a Laser NA, just got the Talon a while ago Too busy fixing drive train problems. Anyways. .. The only noticable problem is bad gas milage, I just figured because it was an AWD Turbo, the milage was worse... but it seems extra bad, and now I see it is running rich, and I want to fix that. I don't wanna be replacing the CAT.

 

[steve]

so I actually want to look at O2R on a 1G? I thought I read somewhere else that on a 1G and MMCD you want to look at O2-F

Lets see, go with something I think I remember reading somewhere or the guy who uses it everyday? Hum, Hard choice.

My O2R is switching between .18 and .74 Volts. Which then it would be working.

That would be an indication that you have the right one and that the ECU is operating in closed loop. Net thing for you to look at the the fuel trims and O2 feedback on the third page to see what sort of corrections the ECU is making to the fuel based on what the sensor is telling it. Fuel trim numbers > 100 mean the ECU is adding fuel to what it calculated should be the right amount. Numbers < 100 mean the ECU is taking away fuel.

Note I don't call them lean or rich since according the O2 sensor after the trims are applied the AFR is 14.7:1 but they are an indication of which way the car will be when it's in open loop.

Is it normal for O2F to be reading 2.08V on a 1G since it only has one sensor??

What the datalogger does is ask the ECU to send the value of a location in RAM. So what your seeing is the value of that location converted as if it was an O2 sensor voltage. Since the 1G doesn't have two O2 sensors what you looking at is some other parameter in the ECU software. On cars like the 3000GT that location is the front O2 sensor.

Steve

 

[zook]

Sorry Steve, didn't mean to offend you. I just wanted to make sure.

So do you mean FTO2?? It's going from 60% to 112%. My fuel trims low med and high are stuck at about 82-83 percent. It doesn't change at all really.

It it's not my mass sensor (Air Flow Sensor then right??), anything else I should be looking at?? I am going around with a volt meter tomorrow after work, so I want to know everythiing I should check that would be related to fuel trims. I will figure this out....with a little help of course!!

Thanks for the input!!!

 

[zook]

Ok, I'm retarded, how about the obvious, like vacuum leaks/intake leaks

I remember someone telling me THINK... I think it was a teacher

 

[steve]

So do you mean FTO2?? It's going from 60% to 112%.

My fuel trims low med and high are stuck at about 82-83 percent. It doesn't change at all really.

It it's not my mass sensor (Air Flow Sensor then right??), anything else I should be looking at??

I am going around with a volt meter tomorrow after work, so I want to know everythiing I should check that would be related to fuel trims. I will figure this out....with a little help of course!!

Yes, FT02 is the real time fuel trim change based on O2 sensor feedback.

FTRL is the low airflow fuel trim. This one updates from idle to a little over 100Hz from the MAF.
FTRM is the mid airflow fuel trim. This one has a narrow range and normally is the slowest to update.
FTRH is the high airflow fuel trim. This one covers from about 200Hz to the point where the ECU goes open loop.

Unless your getting errors related to the MAF it's not very likely it's the problem. It would have to be reading high to make the trims bottom out like that and they don't usually do that.

Yes, you want to go through and make sure you don't have any leaks.

How old is the O2 sensor?

Right now your trims are at, or close to, the "rich" end of their limits. You should be shooting for 100 across the board. It might help to reset the ECU and let it relearn.

Steve