AEM wideband readings

[mattspyder]

Just put my AEM wideband back in. I put it in the 2nd 02 sensor bung (downpipe, and greddy turbo back exhaust no cat)
what should my readings be for a stock setup. when I first start up the car its all the way to the right in the red, it doesn't give me a number. then as the car warms up it will go anywhere from 14-16, usually it idles out at 14.5-9.
while I'm cruising its 14.7 usually and at WOT it's at 13.2 all this sounds normal except for the idle reading. I can't seem to get it to stay still.

 

[TurboJimbo]

Everything sounds normal except for at WOT...it should be around 11.6 where its safe....13.2 is lean

 

[mattspyder]

so the higher numbers mean it's Lean correct?
why would I be super lean at idle?

 

[TurboJimbo]

At idle around 14.7 or alittle leaner is good...14.7 is stoch. (when all the air and fuel is burned)

At cruising speed around 14.7 is also good (you're just cruising, little load on motor)

At WOT, 13.2 is lean...it should be richer around 11.6 where its safe...13.2 is too lean and you can/will damage the motor

 

[mattspyder]

what would cause it to run lean at WOT?

 

[TurboJimbo]

Check the vacuum line to the fuel pressure regulator...cause your car sounds like it idles and cruises fine but at WOT the fuel pressure needs to raise with boost for correct air/fuel ratios...check to see if it popped off or something

 

[9!'clipseDOHC]

what would cause it to run lean at WOT?

Too much boost or not enough fuel. How much boost are you running. What fuel mods do you have?

The reason is reading --- when you first start it and it's idling is most likely a small pre-sensor exhaust leak that is sucking in air. Once you get moving it is no longer an issue. It will most likely do the same thing then you let off the gas at higher rpms and the engine is slowing the car down.

Your idle and cruising sound perfect. The only number of concern is your WOT.

One more question, when you say WOT, how high up in the rpms are you?

Hope this helps!

 

[mattspyder]

I'm running stock boost, with stock injectors and a 190 fuel pump. when I say WOT I mean i'm driving and then I put my foot all the way down.

 

[9!'clipseDOHC]

I'm running stock boost, with stock injectors and a 190 fuel pump. when I say WOT I mean i'm driving and then I put my foot all the way down.

OK but you can have the gas on the floor at 3,000 RPM's and 13.2 is normal. The higher the RPM's go the more boost and your AFR should get richer (numbers get lower). So when you are at 6,000 RPM's you should be in the 11's. That's why I was asking. When you were testing it did you make a high RPM pull and watch the wideband?

 

[mattspyder]

no I didn't make a 6k rpm pull. Tomorrow i'll go for a ride and see what the reading is in a 3rd gear pull to 6k.

 

[JayRolla]

14.7:1 is the perfect afr for power and fuel economy. The car can make good gas mileage and power when at this air fuel ratio. This is what you want to see at low to mid load. Ideally on 91-93 octane pump gas you do not want to run leaner than 11.1:1 AFR at WOT. The car will run leaner at low rpms and bye full boost be at 11.1 or richer.

The stock AFR verys from 1g to 2g but should be around 9.8:1 which is very rich. If your seeing 13.1+ afrs that is very lean unless it was low rpms at low load. Hope this expains some things.

 

[mattspyder]

Just got back from a nice long ride. I did some 3rd and 4rth gear pulls up to redline and it seems to be normal. when I get up past 5k it's in the 11s. I ran it up to redline and noticed it didn't have a reading and all the way to the left so I don't know if thats too rich.

 

[9!'clipseDOHC]

Just got back from a nice long ride. I did some 3rd and 4rth gear pulls up to redline and it seems to be normal. when I get up past 5k it's in the 11s. I ran it up to redline and noticed it didn't have a reading and all the way to the left so I don't know if thats too rich.

Just as I suspected. Glad everything is working like it is supposed to. Usually with stock boost levels it will run very rich at high RPM WOT. That is the way the ECU is programed from the factory to keep everything nice and safe. It would be safe for you to raise the boost a little until you are in the 10.8-11.1 area at your redline if you wanted to. It would also be quite an increase in power.

 

[mattspyder]

i'm at stock boost right now, with my setup what would be a safe boost level?

 

[9!'clipseDOHC]

i'm at stock boost right now, with my setup what would be a safe boost level?

It's hard to just say a number. Usually around 15, but there are too many variables. Turn your boost up a little bit at a time. With every psi you increase, watch your wideband and see what you are hitting at full RPM WOT. Once it gets to about 10.8-11.0 or so, that should be a safe AFR.

 

[rstchris]

That is NO way to tune, all it takes is a boost spike and the head lifts cause lean+boost=no head gasket. Don't max the fuel system until it cannot keep up.

 

[9!'clipseDOHC]

That is NO way to tune, all it takes is a boost spike and the head lifts cause lean+boost=no head gasket. Don't max the fuel system until it cannot keep up.

Obviously the best way to tune is with a logger. But if you don't have a logger and all you have is a wideband then that is how to do it. Also a 10.8-11.0 AFR isn't maxing out your fuel system and you still have some room for unexpected variables.

 

[spyderturbo007]

It's hard to just say a number. Usually around 15, but there are too many variables. Turn your boost up a little bit at a time. With every psi you increase, watch your wideband and see what you are hitting at full RPM WOT. Once it gets to about 10.8-11.0 or so, that should be a safe AFR.

I would advocate against using this method to try and tune your car for a couple reasons. First off, there is no mention of a tuning device, such as a SAFC, DSMLink, etc. That means when you start seeing the AFR creep lean, you are actually running out of fuel. Target AFR is about 9.5:1 at WOT. So as soon as that moves, since we aren't using a device to tune, it means you're running out of fuel.

So basically, you're advocating that he try and lean things out by overworking his fuel system. That is not a good idea.

 

[the_mork]

I still think you have a problem, you should be reading all the way rich on your wideband by 3000rpm and ~3psi boost (90-110 load but you can guess off of your boost gauge). You also should never be all the way lean at idle. Your car should start off with the gauge to the left at around 13:1 and then slowly lean out to stoich (14.7:1) and bounce around that range within a few points so long as you are idling or cruising. The reason for this is that when the car is cold it will use warmup routines and the fuel map to determine fueling without regard to closed loop feedback. As the car warms these routines tell it to lean out toward stoich and hopefully seamlessly transition into closed loop driving. The idea is to get the car warm very quickly and give the average driver a good mannered ride until the car gets there. You have a problem with your car counting air, or providing fuel. You likely have an aberrant fuel pressure, a sticking injector, a boost leak, or a bad maf.

Also for the record air isn't ever going to leak into the exhaust system, it is pressurized at any time that the engine has spark and even has positive pressure when the car has the fuel cut for decel which is the actual reason that it pegs lean when you're going down the hill with your foot off the gas. That is a situation in which the car relies on the force of the pavement rolling the wheel translated through the transmission to keep the engine spinning while it shuts off fuel and spark for better economy. When the rpms drop enough that that computer wouldn't be able to keep the motor going if you suddenly hit the clutch, or where this sudden return to engine power would alarm your average driver then the computer begins fuel and spark again. With an aftermarket exhaust this change is very easy to hear and with a wideband you can watch it happen.

 

[9!'clipseDOHC]

I would advocate against using this method to try and tune your car for a couple reasons. First off, there is no mention of a tuning device, such as a SAFC, DSMLink, etc. That means when you start seeing the AFR creep lean, you are actually running out of fuel. Target AFR is about 9.5:1 at WOT. So as soon as that moves, since we aren't using a device to tune, it means you're running out of fuel.

So basically, you're advocating that he try and lean things out by overworking his fuel system. That is not a good idea.

On this thread the OP's AFR is 10.4:1 and another wiseman says "I would get it to where the gauge reads around 11.8:1-11.0:1."

I just wanted to clarify that I'm not making any numbers up. I agree 100% that you should have a tuner and a logger (or both in one, dsmlink) but not everyone has that. All I have is a wideband o2 sensor (v3 lite is next on my list though).

The way I understood it, and the way that I explained it, was that the point of having a wideband o2 sensor was to view your actual AFR. Then once you know your AFR, you can adjust your boost accordingly. While this isn't as good as having a logger and seeing your IDC's (Injector Duty Cycle) and any knock, it is still better then just turning up the boost to a set number (usually 15psi-17psi), and it can be done safely.

Also for the record air isn't ever going to leak into the exhaust system, it is pressurized at any time that the engine has spark and even has positive pressure when the car has the fuel cut for decel which is the actual reason that it pegs lean when you're going down the hill with your foot off the gas. That is a situation in which the car relies on the force of the pavement rolling the wheel translated through the transmission to keep the engine spinning while it shuts off fuel and spark for better economy. When the rpms drop enough that that computer wouldn't be able to keep the motor going if you suddenly hit the clutch, or where this sudden return to engine power would alarm your average driver then the computer begins fuel and spark again. With an aftermarket exhaust this change is very easy to hear and with a wideband you can watch it happen.

This I may have been confused about. When I first got my AEM UEGO I was having --- at idle and I posted a thread about it and was told that it could be drawing air in. At the time I only had a downpipe, not the full exhaust, so they could have been referring to air being drawn in from the open downpipe, not exhaust leaks. However even after I got the rest of my exhaust on I was still getting the same reading and it was from an exhaust leak at the o2 sensor. Once I fixed the leak, the readings went to normal.

 

[the_mork]

On this thread the OP's AFR is 10.4:1 and another wiseman says "I would get it to where the gauge reads around 11.8:1-11.0:1."

I just wanted to clarify that I'm not making any numbers up. I agree 100% that you should have a tuner and a logger (or both in one, dsmlink) but not everyone has that. All I have is a wideband o2 sensor (v3 lite is next on my list though).

The way I understood it, and the way that I explained it, was that the point of having a wideband o2 sensor was to view your actual AFR. Then once you know your AFR, you can adjust your boost accordingly. While this isn't as good as having a logger and seeing your IDC's (Injector Duty Cycle) and any knock, it is still better then just turning up the boost to a set number (usually 15psi-17psi), and it can be done safely.

I haven't read the thread you linked to but either there is some incorrect information there or else you have misinterpreted it. A fuel map looks like a spreadsheet (mostly because it is one). Load goes up with relation to maf hz and is adjusted by a number of environmental factors, as that happens the ecu moves rightward on the fuel map and downward as rpm goes up. The numbers on the fuel map as we generally see them are the "target" AFR but what is really in the map is simply a number that has a relationship to the length of time the injector is open. The final number comes from a relationship between the amount of airflow we are trying to match with fuel and the length of time that that takes with a given injector flow. Quite frankly it is a hard concept to explain without spending a lot of time playing around with the tables or a previous familiarity with the way that the ecu works.

The important and short explanation is that as airflow goes up the ecu is already set to match airflow with fuel, and it will continue doing this until you hit fuel cut or you reach the physical limitations of your fuel system. The target then for high load is richer than 10:1 and will never become any leaner without a problem in the car. Such as it is then there is absolutely no way that increasing the boost until you reach your desired AFR is the right way to go, it is only possible in that way by overtaxing the fuel system to the point where it cannot reach its targeted AFR. If you have done this then do not go WOT again until it is fixed. What you have done is incredibly dangerous and if anything changes, including a drop in temperature of only a few degrees then you will go even leaner and potentially destroy expensive parts.

Cliff notes:
higher airflow does not equal leaner, instead it means that the ecu calls for more fuel to maintain the same air/fuel ratio, this can only change by tuning, or overtaxing the fuel system.

 

[9!'clipseDOHC]

I haven't read the thread you linked to but either there is some incorrect information there or else you have misinterpreted it. A fuel map looks like a spreadsheet (mostly because it is one). Load goes up with relation to maf hz and is adjusted by a number of environmental factors, as that happens the ecu moves rightward on the fuel map and downward as rpm goes up. The numbers on the fuel map as we generally see them are the "target" AFR but what is really in the map is simply a number that has a relationship to the length of time the injector is open. The final number comes from a relationship between the amount of airflow we are trying to match with fuel and the length of time that that takes with a given injector flow. Quite frankly it is a hard concept to explain without spending a lot of time playing around with the tables or a previous familiarity with the way that the ecu works.

The important and short explanation is that as airflow goes up the ecu is already set to match airflow with fuel, and it will continue doing this until you hit fuel cut or you reach the physical limitations of your fuel system. The target then for high load is richer than 10:1 and will never become any leaner without a problem in the car. Such as it is then there is absolutely no way that increasing the boost until you reach your desired AFR is the right way to go, it is only possible in that way by overtaxing the fuel system to the point where it cannot reach its targeted AFR. If you have done this then do not go WOT again until it is fixed. What you have done is incredibly dangerous and if anything changes, including a drop in temperature of only a few degrees then you will go even leaner and potentially destroy expensive parts.

Cliff notes:
higher airflow does not equal leaner, instead it means that the ecu calls for more fuel to maintain the same air/fuel ratio, this can only change by tuning, or overtaxing the fuel system.

I had never heard this before. So why even have a wideband o2 sensor? All I ever hear is how raising boost without one is reckless and stupid. With what you are saying it seems pretty useless.

Also I apologize to the OP, this is what I was told and what I have been doing. I guess I need to back my MBC back out. But now that I'm thinking about it, even with the MBC all the way out, running off wastegate pressure, I hit 14 psi, which gives me low-mid 10:1 AFRs. I have never seen --- (less then 10:1) due to being rich.

 

[mattspyder]

thats what I figured, everytime I go out into my car in the morning I start it up and it goes all the way lean, then slowly works it's way up to 14.7. LETS FORGET ABOUT TURNING UP THE BOOST, and get this problem figured out first. Also I do have evoscan which I like, just waiting for them to send me the newest version so it works with my windows 7

 

[the_mork]

I had never heard this before. So why even have a wideband o2 sensor? All I ever hear is how raising boost without one is reckless and stupid. With what you are saying it seems pretty useless.

Also I apologize to the OP, this is what I was told and what I have been doing. I guess I need to back my MBC back out. But now that I'm thinking about it, even with the MBC all the way out, running off wastegate pressure, I hit 14 psi, which gives me low-mid 10:1 AFRs. I have never seen --- (less then 10:1) due to being rich.

If you are using an AEM UEGO it will never read any richer than 10:1, and if it says 10:1 you can almost certainly assume you are richer than that.

Why have one? Because a wideband is incredibly important for fuel tuning. It really wont do much for you if you haven't done any tuning except changing the boost unless you happen to see it run lean from overtaxing your injectors or have another problem so that you can shut your car off before breaking something. Until then it is one of the better looking and less laughable gauges on a car. I would never ever do any fuel tuning without a wideband considering how cheap they are today, but I also wouldn't buy one for a car that had stock injectors and no change in the tune.


For mattspyder, I had a hard time finding it as well and even sent a support ticket. A download link has been posted here, and if your username is registered with the software group then you should be able to download it now. I just got it today but I haven't installed it yet. If you continue having problems then send me a pm with your email so that I can send you something to help you out.

Another thing to add to the list of things to check out is your coolant temp sensor, and is the car hard to start ever?

 

[spyderturbo007]

Also for the record air isn't ever going to leak into the exhaust system, it is pressurized at any time that the engine has spark and even has positive pressure when the car has the fuel cut for decel which is the actual reason that it pegs lean when you're going down the hill with your foot off the gas.

This statement is incorrect.

I've actually been through this before. Even now, at idle, my WBO2 moves from about 15:1 to around 17:1 just sitting idle. Due to a trashed motor mount that I haven't had time to replace, the flex section in my down pipe is trashed and leaks. At idle, there is a low enough flow that a Venturi Effect is created at the flex section. This low pressure created by the flow of exhaust gasses causes air to be drawn into the exhaust. This is what is causing my lean condition at idle.

I went through it before, replaced the down pipe making no other changes and the AFR at idle returned to where it should be. So from first hand experience, it does happen.

The way I understood it, and the way that I explained it, was that the point of having a wideband o2 sensor was to view your actual AFR. Then once you know your AFR, you can adjust your boost accordingly. While this isn't as good as having a logger and seeing your IDC's (Injector Duty Cycle) and any knock, it is still better then just turning up the boost to a set number (usually 15psi-17psi), and it can be done safely.

You are correct, the point of a WBO2 is to view and possibly log AFR. The part you are missing is the way that we manipulate the AFR. For example, the SAFC removes airflow, thereby tricking the ECU into injecting less fuel. DSMLink actually drops injector flow resulting in a leaner AFR. The way you are describing lowering AFR involves turning up the boost. The problem is that since you aren't directly or indirectly manipulating fuel delivery, the only way that the AFR will change is when the system actually runs out of fuel.

The ECU contains 3 dimensional fuel and timing maps. Based on defined input parameters, it determines target timing and fuel delivery. What we do with tuning devices is manipulate or directly alter these maps to achieve a desired AFR.

Let's do an example and see if that helps. I'm going to make these numbers up since I don't have fuel delivery maps in front of me but you should still get the point.

Let's say that you are running 1.8g/rev of airflow and the ECU determines that an IDC of 86% is required to hit it's target AFR of 10:1. No matter what you do, without a tuning device or direct access to the ECU's maps, there is no way to change this AFR target and IDC. See where I'm going with this?

What you are saying is to increase boost, thereby increasing airflow until the AFR leans out. So let's turn up the boost and see what happens. With the boost bumped up 5psi, the ECU now sees an airflow of 2.4g/rev and determines that an IDC of 118% is require to hit it's target AFR of 9.5:1. The problem is that an IDC of 100%+ is impossible so the injectors are basically no all the time and injecting as much fuel as possible but actually needs more.

Since we now require more fuel than the system can supply, you'll see the AFR start to lean out. It's 100% the wrong way to tune because you're basically running the system past it's capacity in order to alter AFR.

It might look like it's working, but if anything changes, Boom! Bye, Bye motor.

See why this is a problem?