Tuning Info: Why To Tune and How it is Done

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MJEngineering

New England Tuning
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The most up to date version will always be here: http://m3-industries.com/mje/about.html

Hey everyone, this document was written in order to debunk some myths about tuning and to explain the basic process for those who do not know what we do when we reprogram your vehicle.

What we do is tap into the vehicle's main computer and recalibrate many settings which control the engine. This unlocks power the factory digitally removed from the engine. This added power makes the vehicle more efficient, therefore getting you more MPG!

If you have a custom exhaust, intake, wheels, tires or any other custom engine work, we recalibrate the fuel and spark delivery to match as the stock computer program is now now sending enough fuel to the engine. This will get you more power from your modifications than if you were running the stock computer program. Also the computer will read your modification as an error and not operate as efficiently as possible until reprogrammed for it. The engine's sensors will allow it to continue to operate but at less than ideal settings.

What is EFI LIVE? EFI LIVE is the company which makes the software and hardware we use to reprogram vehicle computers. Anyone can buy it but only engineers can make effective use out of it. Other software packages exist, they all still have to communicate with the same factory computers so the programs are not much different. Kind of Mac vs PC to get to the internet, they both get you the same place but slightly different ways.

Don't forget to read our FAQ!

The following explains some basic ways we adjust those settings:

This is a volumetric efficiency table. It maps the theoretical efficiency of the engine as a pumping device. Every formula the computer uses to calculate fuel and spark delivery starts with this data. You can add all the upgrades, intake, exhaust, boost, you want but you will not make more power at the wheels until this table has been adjusted to reflect your newfound efficiency increases. Any time you make ANY change to the engine's equipment the computer needs to be completely recalibrated. If you do not your engine will in fact run poorly compared to a fully stock setup.

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This is a spark table. The factory sets these data points at a relatively conservative value that will work in all weather, load and fueling conditions. If you supply the engine quality fuel you can alter the ignition timing with this table and create more downward thrust on the pistons, making more power with the same amount of fuel. Equaling more MPG, fun and return on investment. There is no automatic calibration for spark tables, this takes trial and error, and precise measurement therefore they are ideally found using a dyno.
This is where the 87 vs 93 octane tunes come into play. If you have an 87 octane tune you can only run a little more timing than stock, if any. (Giving you only a little more power than stock, if any.) With a dedicated 93 octane fuel source, we can bump the timing up to support a higher level of power than you can safely run on regular gas. "Safely" is used because if the timing is advanced too far the pistons will begin to fight the rest of the crankshaft and will cause excessive wear and heat on your internal parts.

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A word about "free hacks" like MAF modification - Here is your maf calibration, any changes from stock need to be reprogrammed here. As you can see it is accurate to millionths. Changing your maf in any way (inlcuding hacking the screen) will throw this table and your ENTIRE engine programming out of calibration. DO NOT DO IT!

maf.jpg


The maximum amount of power the engine is allowed to produce is hard coded into the computer. This factor will cap any attempts at performance without having been edited. This is one of the two types of torque limiting. The other applies to each shift, removing a slight amount of power depending on speed and throttle position. Many people wonder if this will affect the lifetime of their parts but the answer largely depends on how the vehicle is being driven. If gently used, your setup should last almost indefinitely - abuse tends to shorten that life no matter how much power the computer removes.

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If an engine has had components removed from it for racing purposes, it takes one click to remove the error codes from the computer so that the system will run correctly and not enter failsafe mode.

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We make sure that your wheel and tire combination is exactly recalibrated to real life measurement so that the transmission will shift perfectly no matter how much you change your rolling stock. This is again much easier to do in person as most "35 inch" tires etc are nowhere near 35 and measured height usually changes while in motion especially on the big trucks. We check and set this via GPS or on the dyno. Speed limiting can also be easily changed for racing.

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Once all these variables have been set, the new file is uploaded to the vehicle computer through the port under the dashboard and then tested. It only takes a few moments as if transferring files to a USB drive.

Dyno results are pretty typical for bone stock engines, a small bump in power along most of the curve. As far as custom engines, every one is different and there are plenty of forums to see dyno sheets from every combination. A dyno sheet on a properly calibrated engine pretty much reflects the VE table as mentioned before. Imagine cutting the 3D table 45 degrees through the middle and look at it from the side - that is basically your full throttle dyno curve. New equipment will give you extra bumps in either high end, low end or total volumetric efficiency / torque. One thing we would like to make clear is that the dyno sheet is only a small part of how your vehicle will actually drive and feel. Almost every sheet you have probably ever seen was a WOT run, most driving is not WOT so you will experience different behavior than seen on a sheet.

Some of the best mods for DRIVING don't make that much more power on the top end but give a ton more oomph from a stop or mid range at part throttle which is clearly visible when the VE table is being edited. Deleting torque management doesn't produce much more overall power but it does really also add to the "around town" low end you're actually looking for. Everyone talks about how much horsepower their engine makes - this is in fact pointless because horsepower is usually max at top RPM and 1:1 gear ratio. In almost every vehicle making 300+ horsepower this maximum number is produced at speeds which are not only completely unsafe for most factory vehicles they are downright deadly when used on public roads.

Not all dynamometers are the same. Some use a loading method which essentially reproduces the load at the wheels the test vehicle would theoretically experience while driving in real life. This is the only way aside from actually driving the vehicle to determine the correct data for all calibration. There are other, cheaper dynos out there which are free wheel setups and do not load the vehicle so it is impossible to get accurate data collection for calibration with those devices. The free wheel units also usually read a higher horsepower number at the top end as the engine is revving freely and not against the "weight" of the vehicle.

You can tune the system all you want but unless a HIGH QUALITY wideband O2 sensor is installed in the exhaust of the vehicle you will not be able to achieve a perfect tune. This tool is also essential for boosted engines as the standard O2 sensors are not capable of reading accurately beyond the naturally aspirated stochiometric value of air:fuel (14.6:1). When operating with intake charge above atmospheric pressure, more fuel is required, pushing the ratio into ~10-11 territory and the factory sensors into their blind regions.

A word about diesels - these basic principles apply but the tuning itself is different. The Duramax engines allow for very flexible electronic control and can add extremes of power quite easily. Enough power to quickly break driveline parts, so we typically use a mild tune for diesel owners unless otherwise requested. Multiple tunes on a switch is also common.


Engines that have been drastically changed from stock need drastically altered data tables so they take longer to set up and involve far more than explained here.


Don't forget to read our FAQ!

The methodology and engineering behind these tables is highly advanced and only those with an intimate understanding of the mechanics, fluid dynamics and electronics of these systems can begin to properly calibrate them. Leave this to the professionals! Feel free to contact us with further questions or to have your vehicle tuned!



(C) 2012 MJ ENGINEERING + PERFORMANCE
 
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HOE-N-IT

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Good information. If you could provide similiar detail on tuning the transmissions' TCM especially the GM 6 speed that would also be hepful.
 
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MJEngineering

New England Tuning
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Wanted to add this but the char limit has been hit:

Firstly just a quick run through of the basics before we continue: The engine is an air pump which outputs all energy to a rotating shaft, it is made to turn by air and gasoline vapors burning inside each cylinder of the engine. Due to laws of physics there are understood proper levels of fuel and air to burn in any given engine and driving circumstances. The fuel is ignited to burn by spark plugs, the time that the spark plug ignites during the engine's rotation is critical to how the engine will operate. The engine computer's job is to deliver the right amount of fuel and the correctly timed spark event.
 

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