Is Your Car Tuned Correctly?

Brutal Metal

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Eric, can you outline the post where 91svtbird was trying to drum up any business at all, or where HE SAID PEOPLE SHOULD GO, I must have missed it. The guy is trying to help the membership:bash::mj::bash:
By saying the preferred method of tuning is with a flowbench for MAF transfer?
A smart car owner should monitor their engines parameters with datalogging,wideband 02 readings, especially during WOT street pulls, if an issue is apparent bring it to the tuners attention..
 

truckguy

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I dont see how the initial post is helping the community at all. The main point seems to be that if it isnt done that way then it was done wrong. The issue that most of the tuners out there have with that statement is that it is simply not true. Both methods have margins of error in them and the tuner ultimately has to be the one to make sure that everything falls in line in the calibration.

The op and blackshelby have some very good points and I dont know any tuner that would disagree with these. For example:

1. The maf curve needs to be accurate so that load calculations are accurate
2. The load calculation needs to be accurate so that the spark calculation is accurate
3. The maf calculation needs to be correct so that the torque calculation is correct.
4. If the inferred boost guage in your GT500 is not reading after a tune, then your airflow model is not accurate
4. Just because the fueling is off doesnt mean the maf curve is off

All of those are 100% valid points and are accurate information.

Where the issue comes in is the statement that if it is not done that way, then the car was tuned wrong, the car will drive badly, and the motor will blow up. Reality is that you could get your maf curve from a flow bench and all of these statements could still apply. Why?

1. Maf sensors and cold air kits all have margins of error. If your particular intake and maf wasnt the one flowed, you would most likely have a margin of error in the maf curve. That margin of error would then makes its way into your load calculations, spark calculations, and torque calculations. All things the op and blackshelby are telling you that you need to do things their way to ensure those values are accurate....Granted you would have a small margin of error but there would be an error none the less. In the production world it is probably less of an issue because the manufacturers arent trying to squeeze every last hp out of the car. In the aftermarket world where you are trying to get that last bit of power, this needs to be accurate.

2. Mechanical variances can create issues as well. For example, simply moving the filter further onto the intake tube of a JLT 123mm intake for a GT500 or 5.0 Mustang can drastically affect fuel trims. Why is that? Simply because the filter placement had a direct affect on how the air was moving across the maf which affects the amount of air that gets reported to the pcm, which affects the load calculation and the torqe model... If the intake was assembled on the flow bench one way and installed on the car slightly different, then the airflow model would not be correct.

3. Things like ram air hoods, or poorly fitted hoods can have an impact on how air flows across the maf, especially at higher speeds. If the path of the air changes across the maf at all, then the data going into the pcm is skewed and load, spark, and torque calculations will all be off.

For those that say you cant derive the transfer function without a flow bench, think of it this way. Lets say you have a bone stock car. In theory, the airflow model is correct so your fueling on the car should match what is being requested by the pcm. Now lets say you change the intake. What happens? Your fueling is now off because the new intake changed how the maf reported airflow to the pcm. If your tuner adjusts the curve to get actual fueling back to what the pcm is requesting then everything else falls back in line 100%. This works because in order for the fueling to be correct the airflow has to be correct. This is the premise that tuners are using when doing the maf curves and if done that way, like Greg mentioned earlier, the values in the table would very, very close to values derived from a flow bench. Why? Because you are simply solving a 3 part equation where you know the other 2 parts. Its sort of like finding the third side of a triangle if you already know the first two. Math tells you that you dont have to measure it directly but that you can calculate it. Now with that being said, there are a few things that need to be in order for that method to work and for all of the calculations to come out properly:

1. Everything in the fuel system must be of known values. This means using fuel injectors from companies that supply good data (ie. ford racing, injector dynamics) and if you want to be even more picky about it, pony up and get a flow matched set so you know fueling is precise. If you dont have precise fueling information when back calculating the airflow model, then the airflow model will never be correct.

2. The equipment that your tuner is using MUST be top notch equipment. I personally use dual AFM-1000's (one in each bank) calibrated before each use and require they be mounted as close to the collector as possible to ensure accurate readings. I would never trust air fuel readings from an off the shelf wideband or from a tail pipe sniffer for the purposes of tuning a car. Remember any errors in the reported fueling by those sensors is directly going to impact your airflow model. You wouldnt walk into a doctors office and expect to see him using equipment you saw at walmart. You need to expect the same from your tuner.

3.Talk to your tuner. Ask if they have used your particular intake before. The worst thing you could do is take a vehicle to a tuner with an intake they havent used before, using injectors that he doesnt have data for, and doing something aggressive like install a set of cams and expect the tune to be 100% spot on. That is asking for problems.

4. Make sure that your tuner is competent. Not every fueling error is a maf error. You need a tuner that can identify where the error is coming from so that correct fix can be applied. There are tuners out there that apply every fueling error to the maf and that is not the correct way to do things. Your tuner should be able to look at the big picture and ensure everything is in line. If he cannot do that or you are not comfortable with him, then find someone that can that you are comfortable with.

For those that say they want to help the community, the best way to do so would be to inform them with accurate information. The op and blackshelby certainly have some good information in the thread and they are correct that their are some tuners out there that have created problems by applying all of the corrections to the maf. Dumbing it down to where you simply input data from a flow bench is certainly helpful and has its place if you, the customer, are willing to spend the time and money to have your intake, maf, tb, etc. flowed. There is absolutely nothing wrong with that whatsoever. If you dont have the time or means to do so, then find a reputable tuner that uses sound principle and that can answer questions in a manner you can understand to tune your car.

For those that really want to help the community, how about some of these questions?

1. Is your tuner using lab grade equipment or is he using a $300 budget wideband?

2. Is the location your tuner is placing the wideband giving you accurate information? If its in the tailpipe, think about this. How many leaks are there in front of that wideband? Fueling is pretty much a time based thing. You have to tell the pcm when you move the o2 downstream with longtubes because there is a time shift present. What is the timeshift back to the sniffer?

3. If you have a dbw car, does your tuner actually have access to the dbw parameters and is he doing the etc properly? You would be absolutely astonished how many tuners do not have this access or knowlege and what is even scarier is what that means for you , the consumer....

Honestly, a little common sense goes along way. In my opinion, both methods of tuning the car work but both methods require a competent tuner on the other end. If either part of that equation is missing, well use your imagination....
 

iggster

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For those that really want to help the community, how about some of these questions?

1. Is your tuner using lab grade equipment or is he using a $300 budget wideband?

2. Is the location your tuner is placing the wideband giving you accurate information? If its in the tailpipe, think about this. How many leaks are there in front of that wideband? Fueling is pretty much a time based thing. You have to tell the pcm when you move the o2 downstream with longtubes because there is a time shift present. What is the timeshift back to the sniffer?

I stay away from using tail pipe sniffers, I use a lab grade wideband and pre installed budget wideband and compare both and let the customer know the difference so he could know what to look for.

Other day I seen two shops going at it, after a dyno day a customer got on one shops dyno and they used a tail pipe sniffer shop said whoever tuned this car left the air fuel to lean look what I am getting SMH could it have really been lean or could it be cause the readings from the tail pipe sniffer where inaccurate and possibly the other shop used a lab grade wideband installed by the collector.

It is one thing I see allot of shops do and that is use a tail pipe sniffer and call it accurate. Thats a real issue that should be called out on, not this flow bench stuff, though it is very useful information for the consumer to know it isn't something that should be spread out as if you dont do it, you will blow stuff up
 

iggster

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For those that really want to help the community, how about some of these questions?

1. Is your tuner using lab grade equipment or is he using a $300 budget wideband?

2. Is the location your tuner is placing the wideband giving you accurate information? If its in the tailpipe, think about this. How many leaks are there in front of that wideband? Fueling is pretty much a time based thing. You have to tell the pcm when you move the o2 downstream with longtubes because there is a time shift present. What is the timeshift back to the sniffer?

I stay away from using tail pipe sniffers, I use a lab grade wideband and pre installed budget wideband and compare both and let the customer know the difference so he could know what to look for.

Other day I seen two shops going at it, after a dyno day a customer got on one shops dyno and they used a tail pipe sniffer shop said whoever tuned this car left the air fuel to lean look what I am getting, could it have really been lean or could it be cause the readings from the tail pipe sniffer where inaccurate and possibly the other shop used a lab grade wideband installed by the collector. (I do remember the other shop saying they used a lab grade wideband dunno about the location)

It is one thing I see allot of shops do and that is use a tail pipe sniffer and call it accurate. Thats a real issue that should be called out on, not this flow bench stuff, though it is very useful information for the consumer to know it isn't something that should be spread out as if you dont do it, you will blow stuff up
 

Eric@HPTuners

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Eric,

Mean no disrespect ? You saying something about post I didn't even write.
Yes I was interviewed for tech info and quoted but this is not my post.

Then you bring up a Throttle body that I haven't been involved with for 2 years making misleading statements.

I sold my shop 6 years ago and don't tune for the public.

If anybody is trying to drum up business here it might be you....
Trying talk to down facts about the preferred tuning method in favor of things you do which are less than optimal.

I’ll end it here since I see personal attacks.

Sorry you don’t like Ford’s preferred tuning methods.

Have a nice day.

Jimmy, If I falsely assumed you were behind having this article written and posted then I apologize. The author of the article is not a tuner and you were cited as a source of the information, and now you are here defending it.

My comment about the L&M Throttle Body is very valid, but based on your response already, I am not going to waste anyone's time explaining the hypocrisy.

Just because I tune for a living does not automatically mean I am here to drum up business. There are a handful of other tuners in this thread saying the same thing. I don't think any of us are hurting for business, and Greg Banish to my knowledge doesn't even tune for the public.
 

Eric@HPTuners

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I did in fact state right in the beginning of my article why I put this article together. This article was originally posted in the13’ Gt500 section because of all the tuning issues that members have expressed regarding their cars. It was moved here by the moderator. In case you missed it here is a direct quote below of my reason for writing it in the first place. I can’t say I’m surprised by your reaction to this article but my concern is for the community as a whole not those making money off them.

Quote:
“My reason for posting this information is my concern for the unsuspecting Mustang community, to hopefully educate because of what I see happening with member’s cars with aftermarket tunes.”

I will have to check out that forum to see what issues are being posted, but I am pretty sure nothing in what you have written is explicitly relevant to any tuning issue someone with a 13 GT500 may be having.
 

91svtbird

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Someone sent this thread to me - Warning !! Before you change that tune read this!

Same agenda as this thread.

I actually posted that same link in the 13' section but it was removed by the moderator. I was told I couldn't link to another site. I was told I would need to post the article here directly. That is why I updated it and posted it here on SVTP instead. (see post #15)http://www.svtperformance.com/forums/2013-shelby-gt500-413/877400-2-lund-custom-tunes-still.html

These tuning problems have been going on with the GT500's for quite some time now which is why the article was written in the first place.
 

Tob

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George, you were told that, and more. Let's stay on topic and continue to help "educate" the "unsuspecting Mustang community" "because of what I see happening with member’s cars with aftermarket tunes."

91svtbird said:
Tob it’s unfortunate for the members in the 13’GT500 section that you moved my article “ The Foundation of Mass Air Calibration” out of the 2013 GT500 section...if you think it should be posted in the ‘a-la-cart tuning section also but no way should it be hidden from view in the 13’ section. I thought this site is all about making available good helpful information about the cars to the membership. By removing this thread from this forum I believe you have done a disservice to the members who frequent this forum looking for important information that could help them.

In case I forgot to take the opportunity to apologize for the "disservice" I have done to the members for placing your thread within the appropriate forum, I'll forget it again. You've certainly got your captive audience. Have at it.
 

03Steve

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For those that never adjust the MAF transfer function, please explain how you address the following situation...

Pressure @ injectors = 40psi

AFR (Commanded)
3000 RPM = .78
4000 RPM = .78
5000 RPM = .78
6000 RPM = .78
7000 RPM = .78


AFR (Actual)
3000 RPM = .75
4000 RPM = .79
5000 RPM = .83
6000 RPM = .80
7000 RPM = .77


The error is non-linear. It is both below and above the target lambda for each cell. You wouldn't adjust a linear injector slope in this situation, would you? Do you adjust the open loop fuel table proportionally at each load/rpm cell? That would make your commanded lambda fluctuate, in an effort to create a stable AFR. That doesn't seem right.

I am curious to see how those who NEVER touch a MAF transfer function account for non-linear errors in fueling.

I do agree it is nice to have a known, accurate MAF transfer function. I like the current Pro-M stuff for cars that I work with. I run one on my personal car. They come with a data sheet with an air model built with respect to the meter and air filter that is to be used on the vehicle.

When it comes to multiple vehicles and/or multiple MAFs, should you always assume that repeatability between two MAF transfer functions is always 100%? How about when it comes to blow through?

Sure...there's the HPX Tool and there's other utilities out there based upon tube diameter. There are also each of our own previous air models that we have used in prior combinations. Each of these are starting points.

To say that every PCM will read airflow the same is dismissing several different tolerance factors and assuming 100% repeatability among every meter. That is not a comprehensive method. It is poor practice, in my opinion.

Fun topic. Not sure if my car is tuned correctly. Depends who you ask, according to this thread.
 
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68fastback

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Why is that a problem? Are you assuming that AFR should be flat? That is showing peak load is around where power/tq cross ...seems right since motor needs more fuel/air at peak load.
 

03Steve

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It is a problem because the calibration is commanding a flat air/fuel, and the actual is not.

Assuming that .78 is desired from 3000-7000rpm in this situation, how does one achieve .78 actual without touching the maf transfer function?
 

03Steve

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The problem is that the PCM is not in control. Once you correct the errors, you can adjust the commanded to whatever you like for maximum torque.

How do you (specifically) make commanded and actual match in this case, without touching the MAF transfer function?
 

68fastback

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So the whole intake was not flowerd? Possibly the xfer curve is therefore not accurate?

I'm not a tuner, Steve ...just trying to understand the assumtions.
 

03Steve

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No sweat bud.

Let's say the whole intake was flowed, that the data from the flow testing was used, and the result is this example. The decimal numbers are AFR expressed in lambda, not engine load - FYI.
 

68fastback

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...yep .78 lambda = about 11.4 A/F ...but are those 'actual' numbers hypothetical? I'm wondering if the 'actual' could truly be actual with it was a fully flowed intake.
 

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