Is the stock tune to lean?

6513 Views 16 Replies 8 Participants Last post by 5LHO, Dec 3, 2012

fake

Discussion Starter · Dec 1, 2012

Reason I ask; when I pulled my plugs a few months ago just to look at the condition they were in, the #4 looked lean and had signs of detonation. On the porcelain, it had little black speckles. The other plugs looked OK; with the porcelain mostly white with a very faint tan color. (To lean for my liking still.)

I have read during WOT, the 5.0 dips into the mid-low 12's for the Afr. I have not seen any actual dyno showing this though. I have seen 13's being the norm for the Afr.

Does anybody have a dyno graph showing stock afr?

1 - 17 of 17 Posts

Radar Doc

· #2 · Dec 1, 2012

Attached a screen capture from SCT Advantage III (Pro Racer) showing the WOT fuel table from my factory tune (HYZ5).

With a stoich of 14.079, AFRs at WOT range from 11.97 to 11.53.

I've datalogged enough to know the "measured AFRs" at the O2 sensors follow the commanded "lambse" values derived from this table.

Conditions other than WOT are another story...lean

You probably know a tailpipe sniffer on a dyno is going to read leaner than the O2 sensors, especially with cat converters in place.

Anyway, hope my info gives you an idea of what WOT AFRs look like on a stock tune.

Mike

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5LHO

· #3 · Dec 2, 2012

My datalogger showed the stock tune around 12.7 to 1 at WOT. Off WOT and dawdling, of course the computer tried to have it run stoich as much as possible.

I'm on Procal now and the AFR numbers haven't changed.

Radar Doc

· #4 · Dec 2, 2012

5LHO said:
My datalogger showed the stock tune around 12.7 to 1 at WOT.

Interesting. What are you using to datalog? Does it read in lambda or AFR? Curious if it may be referenced to 14.7 stoich and might be giving you false readings? Just a thought.

I suppose there are differences among factory tunes, but that's a huge difference from mine.

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5.0 Candy REDCS

· #5 · Dec 2, 2012

Some of you guys are downright smart auto folks,and I mean that as an honest complement. It's amazing reading some of these posts and seeing such a vast knowledge of engines,especially tunes per se.
I'm one that sits on the fence while trying to "learn" from you guru's...I guess not everyone know engines to the level some of you seem to comprehend.
Good work guys:bigthumbsup

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adspru

· #6 · Dec 2, 2012

I'll chime in that the actual and commanded AF ratios are nearly identical, but IMO it is extremely important to remember the adjustment to of 14.07 for ethanol infused fuels, it's also important to understand that some places still sell Ethanol free fuel which has a Stoich of 14.7, and as smart as our cars our, they can not differentiate between E15 and E0.

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5LITER_MUENSTER

· #7 · Dec 2, 2012

My 2013 stock tune run 14.1 on wot. Yes 14.1! [email protected] has a good post regarding why factory tune is calibrated to run stoich on wot. I will see if I can find that thread if you guys haven't seen it. I first thought something was wrong with my logger and my track app but my commanded AFR clearly show that is commanding stoich. Haven't blown up my motor yet and I don't baby her either.

The funny thing is that not only does aftermarket tunes such as bama and steeda correct this lean wot, but so does ford racing procal.

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5LHO

· #8 · Dec 2, 2012

Radar Doc said:
Interesting. What are you using to datalog? Does it read in lambda or AFR? Curious if it may be referenced to 14.7 stoich and might be giving you false readings? Just a thought.

I suppose there are differences among factory tunes, but that's a huge difference from mine.

It's a Dashhawk II; it displays in AFR. Regardless if it was referenced for 14.7 or an E10 reference (which is what I assume you're referring to), 12.7 at WOT would still be perfectly safe. I have it set to gasoline, premium, which means no ethanol.

A datalog is only as good as the instrument you use and the sensor resolution it's getting its information from. So far so good on the old Dashhawk II in this application.

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SirJAG

· #9 · Dec 2, 2012

please locate shauns thread about why the factory tune is lean...

5LITER_MUENSTER

· #10 · Dec 2, 2012

SirJAG said:
please locate shauns thread about why the factory tune is lean...

Here is some of many,

http://www.svtperformance.com/forums/2011-2014-mustangs-354/886548-8-explained-little-better.html

http://www.svtperformance.com/forums/11641876-post40.html

http://www.svtperformance.com/forums/11641924-post43.html

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G

· #11 · Dec 2, 2012

5LITER_MUENSTER said:
My 2013 stock tune run 14.1 on wot. Yes 14.1! [email protected] has a good post regarding why factory tune is calibrated to run stoich on wot. I will see if I can find that thread if you guys haven't seen it. I first thought something was wrong with my logger and my track app but my commanded AFR clearly show that is commanding stoich. Haven't blown up my motor yet and I don't baby her either.

The funny thing is that not only does aftermarket tunes such as bama and steeda correct this lean wot, but so does ford racing procal.

SirJAG said:
please locate shauns thread about why the factory tune is lean...

There were a lot of tuning experts who questioned Shaun's conclusions, FWIW.

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5LITER_MUENSTER

· #12 · Dec 2, 2012

Not saying shawn is accurate or am I saying he is not. One thing I know for certain is that my stock tune run and command 14.1 on wot. My dealer also looked at it and said there's nothing to worry about it tho. It's just very surpring to me that a ported injected gas engine can run stoich on wot and survive. I guess ford know what they are doing.

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SSpdDmon

· #13 · Dec 2, 2012

As a tuner in the LS1 world, I can give you my take on what I think is going on. Granted, I've yet to dig into the Ford world.....they usually aren't THAT far apart.

First things first - if the 5.0's come equipped with a factory WBO2 (pretty sure they do), then that means we've got a closed-loop fueling system that's active under most/all conditions (meaning once the WBO2 is up to operating temps). With that in mind, commanded AFR's and actual AFR's will always be very close to identical as long as the calibration is within the achievable ranges of the fuel trims and the O2 sensor is functioning appropriately.

2nd - Whether the cal states 14.07, 14.63, or 14.7 for a stoichiometric rate really shouldn't matter if you can set values in terms of EQ or Lambda. As a tuner, these numbers are much more meaningful as they are independent of a given fuel's stoich AFR. In other words, 1.0 is stoich for E100 just the same as 1.0 is stoich for gasoline.

So, before we judge whether or not the factory cal is too lean (highly unlikely as most factory cals run rich for safety), we need to know what the commanded EQ/lambda figures are AND the conditions under which those values are commanded. Once we know that and we can verify that the commanded and actual values are identical, then we can answer many of the questions in this thread rather easily. Until then, it's all just speculation...

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5LITER_MUENSTER

· #14 · Dec 2, 2012

Viewing data in eq or lambda only simplify stoich values since those data all go by 1 regardless of the content's ratio. Everything else other than stoich is much simpler to read in AFR values since lambda or equivalent ratio does not stay at 1 and some peoples might have to always end up calculating back to AFR. However, I can't speak for the others, but in my case I did plenty of data logging comparing against my track app data, stock tune calibration , and ford racing procal calibration. I can clearly tell you that my factory 2013 GT usually will stoich on wot, which is 14.1 for e10 compensation. This data is also backed up by the same commanding values. Ford racing calibration on other hand showed normal calibration values very close to what most of us are used to seeing, 12.1-12.5 on wot.

Only person that seemed to have much more knowledge than most of us here and really got into it and spoke out on this with posted data is [email protected] Not even my dealer knew too much except assuring that if anything go wrong they will take care of it.

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Radar Doc

· #15 · Dec 3, 2012

5LHO said:
It's a Dashhawk II; it displays in AFR. Regardless if it was referenced for 14.7 or an E10 reference (which is what I assume you're referring to), 12.7 at WOT would still be perfectly safe. I have it set to gasoline, premium, which means no ethanol.

A datalog is only as good as the instrument you use and the sensor resolution it's getting its information from. So far so good on the old Dashhawk II in this application.

Ok, so your Dashhawk II is simply multiplying the lambda value from the OBD port x 14.7, giving you an AFR readout of 12.7. This equates to .86 lambda, which coincides closely with the factory values I posted earlier. And so my point is your Dashhawk interpreting the lambda of .86ish is nearly the same as my SCT reading .85 from the factory wideband. Your AFR value is actually about the same as my stock tune if you were to use 14.079 for stoich as the factory tune does. It is perfectly safe. Never meant anything otherwise. Now, if your 12.7 was referenced to 14.079 stoich, that would equate to .90 lambda, which I would consider unsafe for the factory E10 tune.

And back to the OP's request for dyno sheets showing AFRs...You'll find AFR values all over the place, just like the HP/Torque values from one dyno to the next. Because of placement of the sniffer and the stoich reference used to calculate the AFRs. I think it's better to monitor the values from the factory widebands vs a tailpipe sniffer.

Also, unless you did a WOT pull and immediately shut the car off to pull the plugs, your plug readings aren't necessarily from WOT mixtures. You're seeing the result of the computer trying to run stoich just about everywhere else but WOT, and this will make the plugs look like that. Finally...just my preference...I wouldn't pull plugs from an aluminum-headed engine while it's hot, risking galling the threads in the spark plug holes. I would just stick to reading the lambda values from the factory wideband O2 sensors.

As mentioned quite a bit, working in lambda is much easier than trying to convert the AFR readings. Then it doesn't matter which fuel you're using or referencing to.

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fake

Discussion Starter · #16 · Dec 3, 2012

Radar Doc said:
And back to the OP's request for dyno sheets showing AFRs...You'll find AFR values all over the place, just like the HP/Torque values from one dyno to the next. Because of placement of the sniffer and the stoich reference used to calculate the AFRs. I think it's better to monitor the values from the factory widebands vs a tailpipe sniffer.

Also, unless you did a WOT pull and immediately shut the car off to pull the plugs, your plug readings aren't necessarily from WOT mixtures. You're seeing the result of the computer trying to run stoich just about everywhere else but WOT, and this will make the plugs look like that. Finally...just my preference...I wouldn't pull plugs from an aluminum-headed engine while it's hot, risking galling the threads in the spark plug holes. I would just stick to reading the lambda values from the factory wideband O2 sensors.

As mentioned quite a bit, working in lambda is much easier than trying to convert the AFR readings. Then it doesn't matter which fuel you're using or referencing to.

I pulled the plugs later that afternoon, so the engine was cool. When I did a WOT run earlier in the day; I could hear the pinging. The only plug that had the black speckles on it, was #4.

I guess I am going to eventually break down and get a tune. During the summer it gets HOT here. 100+ everyday!!! I do run 90 octane, since there is no 91 here at quality stations. While crusing, I would like my AFR to be mid-high 13's; not in the 14's. When I go to WOT, I would like mid-low 12's. Low 12's may be a tad rich, but I want to be safe; especially during the summer months.

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5LHO

· #17 · Dec 3, 2012

Yes it's a gauge value, not related to the stoich value selected by the gas chosen, as it often shows 29.xx:1 off the gas completely, for example, which is the peg of the gauge, top end.

IMHO, lambda is easier for tuning but, AFR is easier to read on the road. Lots of conversion charts laying about for either way though.

Engines like this one are in closed loop virtually all the time and are constantly trimming fuel to optimize for commanded AFR and alot of other parameters. The amount and speed of modern processors makes this real-time tuning actually possible.

Radar Doc said:
Ok, so your Dashhawk II is simply multiplying the lambda value from the OBD port x 14.7, giving you an AFR readout of 12.7. This equates to .86 lambda, which coincides closely with the factory values I posted earlier. And so my point is your Dashhawk interpreting the lambda of .86ish is nearly the same as my SCT reading .85 from the factory wideband. Your AFR value is actually about the same as my stock tune if you were to use 14.079 for stoich as the factory tune does. It is perfectly safe. Never meant anything otherwise. Now, if your 12.7 was referenced to 14.079 stoich, that would equate to .90 lambda, which I would consider unsafe for the factory E10 tune.

And back to the OP's request for dyno sheets showing AFRs...You'll find AFR values all over the place, just like the HP/Torque values from one dyno to the next. Because of placement of the sniffer and the stoich reference used to calculate the AFRs. I think it's better to monitor the values from the factory widebands vs a tailpipe sniffer.

Also, unless you did a WOT pull and immediately shut the car off to pull the plugs, your plug readings aren't necessarily from WOT mixtures. You're seeing the result of the computer trying to run stoich just about everywhere else but WOT, and this will make the plugs look like that. Finally...just my preference...I wouldn't pull plugs from an aluminum-headed engine while it's hot, risking galling the threads in the spark plug holes. I would just stick to reading the lambda values from the factory wideband O2 sensors.

As mentioned quite a bit, working in lambda is much easier than trying to convert the AFR readings. Then it doesn't matter which fuel you're using or referencing to.

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