What would 110 fuel do to a stock engine?

[blondiez24gt]

I filled My grand am up with cam2 at a gas station in parkersburg west virginia once. It seemed to run better with it. I think it was 104 unleaded. I know I prolly didn't gain any power with it, but it sure ran smoother, and seemed like it had better acceleration.

[Shock24Z]

Originally Posted by AaronGTR

and you can't run the car without the main O2 sensor.

Well they run without them on start up... and at WOT. But beyond that, you just tune to correct your fuel trims to zero. Then your O2 serves you no purpose anyways. So you pull the O2 and you can run leaded gas. A positive here would be the ability to run at leaner mixtures than stoich too. I've seen people do it on cars they daily drive.

Removing the O2 from a modern car doesn't automatically remove its daily driving privileges. Daily driver is a subjective term.

[AaronGTR]

Originally Posted by Shock24Z

Well they run without them on start up... and at WOT. But beyond that, you just tune to correct your fuel trims to zero. Then your O2 serves you no purpose anyways. So you pull the O2 and you can run leaded gas. A positive here would be the ability to run at leaner mixtures than stoich too. I've seen people do it on cars they daily drive.

Removing the O2 from a modern car doesn't automatically remove its daily driving privileges. Daily driver is a subjective term.

It doesn't use it at start up or WOT, but it uses it the rest of the time which is 90% of your driving in a daily driven vehicle. You can tune your fuel trims better, but it is virtually impossible to tune them to zero. Best you can hope for is plus or minus 4% or maybe 2% if you are really good/lucky. There are always things that will change the necessary fuel trim as well, such as different conditions from when you tuned in the fuel trims. Changes in elevation, atmospheric pressure, and temperature can affect them. Although these are somewhat accounted for with other sensors, their adjustments are not 100% accurate. They are just calculations and not based on whats actually happening in the engine which is the reason for the O2 sensor and fuel trims. The main two fuel adjusters for the car are the MAF and O2, and I think removing one of them would be stupid. Doing so would certainly hurt your gas mileage, and possibly cause the car to not drive as smoothly and trouble free.

[Shock24Z]

What if i can run leaner than stoich in open loop and get significantly improved gas mileage? That's not stupid. Not to me at least.

And regardless of that....

Originally Posted by Shock24Z

Removing the O2 from a modern car doesn't automatically remove its daily driving privileges. Daily driver is a subjective term.

[Shock24Z]

Ok Well these two statements conflict if you read the first one to be 100% of the time. I don't want to mislead anyone.

Originally Posted by AaronGTR

and you can't run the car without the main O2 sensor.

Originally Posted by AaronGTR

It doesn't use it at start up or WOT, but it uses it the rest of the time which is 90% of your driving in a daily driven vehicle.

What if i can run leaner than stoich in open loop and get significantly improved gas mileage? That's not stupid. Not to me at least.

And regardless of that....

Originally Posted by Shock24Z

Removing the O2 from a modern car doesn't automatically remove its daily driving privileges. Daily driver is a subjective term.

[AaronGTR]

Ya know what..... I'm not trying to be a d!ck here but.... this is getting really old. I have better things to do than keep going back and looking up info I've read in my manual to make sure I'm right about what I said because you keep contradicting me.

The pcm doesn't use the O2 sensor during start up or WOT because that's the way it was designed to work. If it doesn't see the O2 sensor warm up and start working within a certain amount of time after startup (and depending on coolant temp) it freaks out. It doesn't use it during WOT because it's not accurate enough and it uses other sensors and tables for fueling. The rest of the time... it's DESIGNED to use the O2 sensor. As the manual states, the MAF and O2 are the main two primary sensor that determine fuel adjustment. Taking one of them away is not logical and will probably compromise the engines driveability somewhat. I've certain noticed when I've had O2 sensors foul and not working optimally that my engine runs worse. The O2 can compensate for a number of things, and is also a safety net. According to the manual it can correct fueling, to a certain degree, for a number of malfunctions such as abnormally low fuel pressure, faulty injectors, etc. It's just smarter to have it.

No one needs to run leaded race gas bad enough in their modern fuel injected grand am that they need to remove their O2 sensor. Period.


And if you want to do this...

What if i can run leaner than stoich in open loop and get significantly improved gas mileage? That's not stupid. Not to me at least.

And regardless of that....

That's really easy. It's so easy I'm surprised you even brought it up. Go into your fueling tables and set target AFR during closed loop to something higher than 14.7:1.... ta da leaner than stoich and better gas mileage. That was hard.

[Shock24Z]

Originally Posted by AaronGTR

I have better things to do than keep going back and looking up info I've read in my manual to make sure I'm right about what I said because you keep contradicting me.

Well if I know you're wrong, and I can prove it, then I have a hard time just walking away.

Originally Posted by AaronGTR

No one needs to run leaded race gas bad enough in their modern fuel injected grand am that they need to remove their O2 sensor. Period.

I beg to differ. Angrysk8rs car saw huge gains on leaded race gas. He ran it in his daily driver turbo grand am and it's still fine. This proves the fact that you CAN, not that you should. It was HIS decision as to whether it's worth it or not. That part is a matter of opinion.

So, you may assert your opinion, but try not to state it as a fact.

Originally Posted by AaronGTR

That's really easy. It's so easy I'm surprised you even brought it up. Go into your fueling tables and set target AFR during closed loop to something higher than 14.7:1.... ta da leaner than stoich and better gas mileage. That was hard.

See I don't really want to argue this either ... but that's just plain incorrect. You can set it to 15:1, but the O2 knows better, and it'll correct to the real stoich of 14.7:1. Go try it.

If I put e85 in my tank and have the targeted stoich set to 14.7:1, fuel trims are still gonna try to correct to 9.7:1 or whatever the actual stoich is.

The O2 doesn't care what gas you have, it'll correct to the real stoich value if its plugged in.

[AaronGTR]

Originally Posted by Shock24Z

See I don't really want to argue this either ... but that's just plain incorrect. You can set it to 15:1, but the O2 knows better, and it'll correct to the real stoich of 14.7:1. Go try it.

If I put e85 in my tank and have the targeted stoich set to 14.7:1, fuel trims are still gonna try to correct to 9.7:1 or whatever the actual stoich is.

The O2 doesn't care what gas you have, it'll correct to the real stoich value if its plugged in.

Wrong.

E85 has a different stoich AFR so obviously if you put that in your tank without correcting the fueling requirements it's going to run lean and the O2 is going to correct trims to what it "thinks" should be 14.7:1 based on oxygen content. Of course with that fuel it won't actually be 14.7:1

With regular gas or race gas, the ideal AFR is still 14.7:1. The O2 knows where 14.7:1 is based on voltage... it's also knows where 15:1 is and where 14:1 is etc etc. It's doesn't just read 14.7:1, it has a range. It's just narrower than a wideband. If you set the target AFR for 15:1 in closed loop mode, the O2 sensor can read that from it's voltage and it will correct the fuel trims so that you run in that range. I've tried it and it does work, so I already know you are wrong.

The O2 sensor tries to keep you in the AFR range you tell it to be in, not just always 14.7:1.

[3800SII]

Originally Posted by AaronGTR

Wrong.

E85 has a different stoich AFR so obviously if you put that in your tank without correcting the fueling requirements it's going to run lean and the O2 is going to correct trims to what it "thinks" should be 14.7:1 based on oxygen content. Of course with that fuel it won't actually be 14.7:1

With regular gas or race gas, the ideal AFR is still 14.7:1. The O2 knows where 14.7:1 is based on voltage... it's also knows where 15:1 is and where 14:1 is etc etc. It's doesn't just read 14.7:1, it has a range. It's just narrower than a wideband. If you set the target AFR for 15:1 in closed loop mode, the O2 sensor can read that from it's voltage and it will correct the fuel trims so that you run in that range. I've tried it and it does work, so I already know you are wrong.

The O2 sensor tries to keep you in the AFR range you tell it to be in, not just always 14.7:1.

Damn good info! I need to learn how to lean my injectors and tune the MAF anyway, but this is good to know.

[lone_wolf025]

Originally Posted by Shock24Z

Well if I know you're wrong, and I can prove it, then I have a hard time just walking away.



I beg to differ. Angrysk8rs car saw huge gains on leaded race gas. He ran it in his daily driver turbo grand am and it's still fine. This proves the fact that you CAN, not that you should. It was HIS decision as to whether it's worth it or not. That part is a matter of opinion.

So, you may assert your opinion, but try not to state it as a fact.

Ok you just proved yourself wrong. Look at what we've been saying. Its useless UNLESS you're running high compression OR TURBO. And lookie there...he's running a turbo. Oh and modern day valve train components are not designed to work in tandem with the lead coatings they build up from using leaded fuels. Eventually something WILL give.

See I don't really want to argue this either ... but that's just plain incorrect. You can set it to 15:1, but the O2 knows better, and it'll correct to the real stoich of 14.7:1. Go try it.

If I put e85 in my tank and have the targeted stoich set to 14.7:1, fuel trims are still gonna try to correct to 9.7:1 or whatever the actual stoich is.

The O2 doesn't care what gas you have, it'll correct to the real stoich value if its plugged in.

The O2 doesn't do any correcting. All it does is measure voltage between the 100 mv and 900 mv range based upon oxygen content in the air. It is the PCM which interprets this voltage signal and makes the predetermined corrections based on the tables provided. Regardless 14.7:1 is the idea fuel trim for ideal emission purposes when burning gasoline. Why you think its some magical wonderful number I don't know.

Straight up ethanol contains 34% less energy by volume than gasoline. A typical engine will consume 51% MORE ethanol than gasoline over the same conditions.

But hey what do we know. If you wanna run e85 on your car or 110 racing fuel and no O2 sensor you go right ahead. But don't come back here crying because you popped a piston or you're running slower than molasses or you have fuel system problems.

[Shock24Z]

Originally Posted by lone_wolf025

Ok you just proved yourself wrong. Look at what we've been saying. Its useless UNLESS you're running high compression OR TURBO. And lookie there...he's running a turbo.

I know. and he daily drove it. Often times with leaded gas in it. It's still fine. It was a turbo car that often times ran leaded gas and was daily driven. We saw benefits from it and it still runs fine.... I'm missing where I contradicted myself. I never said turbo cars can't be daily drivers. I was trying to say that they can be.

Originally Posted by lone_wolf025

Oh and modern day valve train components are not designed to work in tandem with the lead coatings they build up from using leaded fuels. Eventually something WILL give.

I've never really heard about leaded gas wearing out internals, but that would be a legitimate reason not to. I'll research that further before trying it again in the future.

Originally Posted by lone_wolf025

But hey what do we know. If you wanna run e85 on your car or 110 racing fuel and no O2 sensor you go right ahead. But don't come back here crying because you popped a piston or you're running slower than molasses or you have fuel system problems.

Well I do run e85 on my car with an O2 sensor, it's fine. No KR. That's not likely to pop a piston. On Angrysk8rs car we managed a 13.3 at 112 and it still runs fine. Not to mention it's one of the fastest known Grand Ams in the nation... I'm not suggesting you run without one, but you can do it if you tune it properly.

Originally Posted by AaronGTR

Wrong.
E85 has a different stoich AFR so obviously if you put that in your tank without correcting the fueling requirements it's going to run lean and the O2 is going to correct trims to what it "thinks" should be 14.7:1 based on oxygen content. Of course with that fuel it won't actually be 14.7:1

I think I see what you're thinking. You're saying that when the target AFR is set to 14.7, the computer will say, "hey, they want stoich, so I should try to hit 450mV on the O2 because that's stoich for gasoline." Or if you set target AFR to 15:1, it'll say, "hey, they want 15:1 i should hit xxx mV on the O2." That's not really how it is.

If that were the case, then when I command 9.7 as my target AFR for e85, and I do, then the computer would look up the the mV value for 9.7:1 with respect to the 450mV at 14.7 for gasoline and try to hit that mV value. And it doesn't do that.

You really have to accept the fact that the O2 is blind to what fuel you're using, and a lot of fuel mixtures out there aren't 14.7:1. e10 is in a lot of tanks. So even though the target AFRs are set to 14.7:1, the O2 will target the real stoich value. If you know the real stoich value (or approximate) like in my e85 case, you set it to that value, and the O2 makes minimal corrections.

If it was as simple as changing the target closed loop AFR, why do the following threads contain so much discussion? The simple reply would be, "change target AFR."... but it isn't.

http://www.powrtuner.com/index.php?s...hl=lean+cruise

I have been trying to lean out my car a little during my highway cruise and I am having no luck at all.

Forcing open loop is how I have typically seen people do it.

http://www.powrtuner.com/index.php?s...hl=lean+cruise

you need lean burn mode enabled to do this in our cars. we don't currently have access to it. There is a thread that we experimented with and changing the stoch AF ratio even up to 22:1 didn't change actual AF ratio

^North American cars must run stoich in closed loop. It's an emissions thing.

http://www.powrtuner.com/index.php?s...en+loop+tuning

PE is not really open loop.. It is just not stoich.. If you want to run with non-stoich AFRs for an extended period of time, real open loop is the way to go.....

...Even if you tune it open loop with a wideband, the car is going to use the narrow band when you plug it back in and make fuel trims based on that narrow band. What ever the narrow band says is stoich (even if your wideband doesnt agree) is what the car is going to try to reach.

Beyond ALL of this. Lets say changing the target AFR worked. You wouldn't want to run 15:1 all the time. Open loop tables allow you to do it at certain loads.


I'm kinda enjoying this discussion actually, it breaks up the monotony of CAI and Muffler threads.

[AaronGTR]

Originally Posted by Shock24Z

I think I see what you're thinking. You're saying that when the target AFR is set to 14.7, the computer will say, "hey, they want stoich, so I should try to hit 450mV on the O2 because that's stoich for gasoline." Or if you set target AFR to 15:1, it'll say, "hey, they want 15:1 i should hit xxx mV on the O2." That's not really how it is.

omg do you ever stop? Yes, that is in fact how it really is.... The DHP tuner has a table for target AFR during closed loop. If you change the number, it WILL change the average AFR the car runs at during closed loop. I've tested and VERIFIED it with my wideband!!!

If that were the case, then when I command 9.7 as my target AFR for e85, and I do, then the computer would look up the the mV value for 9.7:1 with respect to the 450mV at 14.7 for gasoline and try to hit that mV value. And it doesn't do that.

Well DUUUUUH it doesn't do that. It's a NARROW BAND... IT CAN NOT READ 9.7:1 SO IF YOU COMMAND 9.7:1 IT WON'T GET YOU THERE! It will only go so low or high.

You really have to accept the fact that the O2 is blind to what fuel you're using

didn't I just F'ing say this?

and a lot of fuel mixtures out there aren't 14.7:1. e10 is in a lot of tanks. So even though the target AFRs are set to 14.7:1, the O2 will target the real stoich value. If you know the real stoich value (or approximate) like in my e85 case, you set it to that value, and the O2 makes minimal corrections.

Again, I just said that. The O2 will make adjustments for what it thinks is 14.7:1 based on the oxygen content it sees in the exhaust gas, even though it may not be a true 14.7:1 based on the fuel you are using. Almost every gas station in america is using e10 though and has been for years so I don't see how that is relevant to the issue.


And as for that quote you posted about PE not really being open loop... what was that person smoking? I want some. They obviously don't know jack **** about tuning. PE is open loop period... meaning it doesn't use the O2 sensor to make fueling adjustments while in PE mode. The O2 still sends a signal and you can still scan the voltage, but it makes no adjustments based on it. It says this very clearly in the manual and leaves very little room for argument.

[Shock24Z]

First off. Calm down. I'm not making any personal attacks.

Originally Posted by AaronGTR

omg do you ever stop?

It would be a shame if I was correct and gave up because of these kinds of remarks. If I'm wrong, I'll thank you for helping me understand something. Right now you're not convincing me though.

Originally Posted by AaronGTR

Yes, that is in fact how it really is.... The DHP tuner has a table for target AFR during closed loop. If you change the number, it WILL change the average AFR the car runs at during closed loop. I've tested and VERIFIED it with my wideband!!!

Well once again, I can't explain your results, but you're one person on the internet telling me opposite of what I've read many times in the past. I've no reason to trust your results over what I've read on the PT forums.

Originally Posted by AaronGTR

Well DUUUUUH it doesn't do that. It's a NARROW BAND... IT CAN NOT READ 9.7:1 SO IF YOU COMMAND 9.7:1 IT WON'T GET YOU THERE! It will only go so low or high.

If thats true then I'm missing the part why I can set it to 9.7:1 and have nice trims on e85.

Originally Posted by AaronGTR

didn't I just F'ing say this?

Perhaps. I apologize if I overlooked it or didn't pick up on it.

Originally Posted by AaronGTR

Again, I just said that. The O2 will make adjustments for what it thinks is 14.7:1 based on the oxygen content it sees in the exhaust gas, even though it may not be a true 14.7:1 based on the fuel you are using.

OK. If nothing else, you MUST agree that this is at least a confusing way of wording yourself. The O2 is blind to what fuel it sees, but it targets the stoich AFR for gas?

Back to the e85 scenario, if I set my target AFR to 9.7, but lets say I have some extra gas in the tank so stoich happens to actually be 10, The O2 will see that I'm a little rich by a certain percentage and tell the pcm to add fuel. Now it's running at 10:1. Can you confirm that this much would happen?

There's no mention of 14.7 in there, and there's no choice but to run stoich.

Originally Posted by AaronGTR

And as for that quote you posted about PE not really being open loop... what was that person smoking? I want some. They obviously don't know jack **** about tuning.

Blemke is a respected tuner in the PT community. He was trying to illustrate the point that the narrowband is still plugged in. I don't think whether or not you call that open loop by definition is important so long as you understand the o2s are ignored.

Go ahead and throw out that point if you like, that's getting away from the topic at hand. And you're still not acknowledging the other two posts. Why should anyone believe you over them?

[Shock24Z]

http://www.hptuners.com/forum/showth...ed+loop+stoich

The stoich value in the file is only used for EQ calculation (divided by the OLFA, PE, COT, etc ... tables to assist in calculating the injector pulse width), nothing more. The narrowbands do not know of that value, all they care about is what the O2 switch point is in the file.You can set the stoich to 12.00 and have the O2 switch point set at 600mv, in closed loop the O2 will average around 600mv.

The bolded part is important to understand, and confirms what I've been saying.

Since us PT users can't change the switch point, that stays at 450. 450 is stoich for any fuel on a narrowband. The O2s will average around the switch point.

This is all ultimately says (with the addition of a PT clause): If your O2 is plugged in, and you can't change the switch point because your PT is obsolete , you must run stoich.


http://www.hptuners.com/forum/showth...ed+loop+stoich

I then changed the stoich to 15 to try lean cruise. The pcm started adding fuel thus positive trims. Just a little food for thought.

That DIRECTLY contradicts your findings.

http://www.hptuners.com/forum/showth...ed+loop+stoich

The guy in the first post of this thread says he set the closed loop target AFR to 12.92....

Here was the reply:

The stoich would make a difference in open loop only, as in closed loop, it cycles rich/lean on the O2's, which only cycle at near 14.6, meaning unless you get O2's that cycle at a different AFR, the AFR after fuel trim will remain the same near 14.6 in closed loop.

See why I'm skeptical of you?

[AaronGTR]

Whatever. I'm just pissed off 'cause I'm having a bad week and I'm tired of repeating myself.

-I know what results I've seen from my own testing and tuning.

-I can not verify or quantify what someone else does with a different car and a different tuner.

-I'm done with the thread. Have a nice week.

[AleroB888]

I might do an experiment to test these theories....

Now suppose I start up the car, let it warm up and record the scan.

Then, I reflash the PCM for say, 16.00 Stoich AFR. Restart the car, let it run for several minutes. What do you predict will show up on the scans?

I can only let it idle at this point, we got a ton of snow out there today

Also, here is some info that appears in the HP Tuners Editor Program when you click on "Help" for explanation of the "Stoich AFR" seen in the fuel calibration. It appears to be generic for GM, though, probably a V8 calibration.

Stoich Air Fuel Ratio (Stoich AFR)

Stoich AFR: This value is the Stoichiometric AFR value. This is the reference AFR used by all fuel calculations inside the VCM. Deviations from this value are represented by divisors where greater than one is richer and less than one is leaner. Changing this value will effect all fuel calculations.

Stoich AFR Table: This table is used for vehicles with the dual fuel option (alcohol)
The base stoichiometric fuel/air rate is determined by a returned value from this table. The position on the table is determined by the amount of alcohol in the fuel system as reported by the vehicles fuel composition sensor. The rate ranges from 0% to 100% alcohol.

[Shock24Z]

Originally Posted by AleroB888

I might do an experiment to test these theories....

Now suppose I start up the car, let it warm up and record the scan.

Then, I reflash the PCM for say, 16.00 Stoich AFR. Restart the car, let it run for several minutes. What do you predict will show up on the scans?

Normal fuel trims in the first scan followed by abnormally high positive trims.

Originally Posted by AleroB888

I can only let it idle at this point, we got a ton of snow out there today

That's fine, so long as it has time to learn the new trims. I would reset the trims on the new write. Or at some point between the first and second scan.

After the flash, the car might stumble as it goes into closed loop before it learns the new trims.

Edit: Actually, startup after the flash might be rough until it goes into closed loop and starts learning trims. Judging by the available tables to me in the powrtuner, I'm guessing that changing the closed loop stoich value will change the open loop values as well.

Depending on how your car runs, we should be able to find out which case it is.

[SpyhunteR]

You guys are making my head hurt. I have seen so far, dead on, off the beaten path, wrong, right.. info all over this... woah. wack.

[Shock24Z]

Originally Posted by SpyhunteR

You guys are making my head hurt. I have seen so far, dead on, off the beaten path, wrong, right.. info all over this... woah. wack.

Care to weigh in?

[AleroB888]

Originally Posted by SpyhunteR

You guys are making my head hurt. ..........

On with the discussion, then! You are suffering from the onset of GRNDMA's Curse, which will haunt you forever.