The 20-20 Tow Tune, a tutorial:

McRat

Diesel Hotrodder
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Aug 1, 2006
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www.mcratracing.com
Just got your EFILive? Perhaps a little intimidated by it?

Here's how you can build a 50rwhp Tow Tune in less than 20 minutes that's safe and sane:

First, download the latest version of the EFILive software and USB driver from the www.efilive.com site. You will use the V3 USB driver. The distribution disk often does not have the latest release, which is true for all software.

Next, make sure your battery on both your laptop and truck is in good shape.

If you have a handheld tuner loaded in your truck RETURN TO STOCK.

Plug the cable into your USB of your laptop, and the other end into the data port of the truck. Turn your ignition to the RUN position (BUT DO NOT START THE TRUCK). Launch EFILive tuning tool. If it says DEMO MODE, make sure you loaded the USB driver from EFILive.

Download your stock tune: FLASH->READ PCM CALIBRATION
This will take about 3 minutes. Turn off ignition for 15 seconds. SAVE the calibration "MyTruckStockECM". Copy it to at least 2 computers. You need to make sure you always have a copy of your stock tune. Now SAVE AS "TowTune" or some other working name, just to be safe.

Now click the EDIT pull down on the top left, and click Configure Display Units.
Click the ALL button, then the IMPERIAL button, then OK. Now we will be in American units. This way we are talking about the same numbers.

Now to tune!

Fake Injector Mod
First we are going to do the "Fake Injector Mod". This will make the engine think you put 50HP injectors in the truck by increasing how much fuel it shoots in everywhere. In the upper left corner of your screen is a box that says NAVIGATOR. This allows you to go straight to an area you want to. You can also click on ENGINE OPERATION->FUEL QUANTITY, etc and find it using the navigator "tree" off on the left side.

Type B0721 (0=zero, not "O"regano) in the Navigator box. Up will pop the Main Injection Pulse (No Pilot). This table tells the engine how long to leave the injector open to get a desired amount of fuel. So if the engine wants 100mm3 of fuel at 160MPa fuel pressure, it will leave the injector open 1526 microseconds to get it on a LLY. The No Pilot means this table is used when the pilot injection is off (high engine output).

Click on the upper left grey square in this table (between 0 and 0) and it will select the whole table. CNTL-A will do the same. In the top middle of your screen is a box that says ADJUST. Type 20 in this box. Now click the % button just to the right of the ADJUST box. Congrats! You have just installed 20% over injectors!

Repeat this with B0720 Main Injection Pulse. This is the table used when the pilot injection is on.

Fake Resistor Timing Mod
Adding some timing can make more power, get better mileage, and reduce EGT's. But making a timing table can be quite a chore. So we will steal one from General Motors! We know this is fairly safe timing because GM uses it.

Navigator - B0908 Injection Timing (A). This is a table used for setting the timing at very high altitude. It has more advance than the low altitude table. Select the whole table (ctrl A) and copy (right click mouse, COPY or hit ctrl C). Now, NAVIGATOR - B0909 Injection Timing (B), click the upper right corner, and hit ctrl V which is paste. Navigator - B0910 Injection Timing (C), paste again. Now all three tables should look exactly the same.

This has the same effect as putting a resistor in the Barometric Sensor to get more timing, but it is well within safe limits.

Fake Boost Stick
This applies to only LLY's. If you have an LB7, you will have to get a crack pipe or Big Head waste gate mod.

Navigator - B0202 Boost Sensor Scaling. Click on the grey 1.09 volt box, hold down the mouse button, and drag all the way to 5.0 volts. You should have just 1.09 to 5.0 (and inbetween) selected. In the ADJUST box, type in -20 (negative) and hit the % button. At 5.0v it should read about 42. What we did was to fake the engine into seeing less boost than there is by 20%. The reason we start at 1.09v, is because 1v is atmospheric pressure, and if we did the whole thing, it would try to make more boost at idle, which is not necessary.

You will notice that there is a dip in the graph up top at 1.09v, and when you look at the numbers, it goes 12.4, 13.9, 12.3, 13.5, 14.7. We want to smooth this out. So at 12.3, type 14.5. At 13.5, type 14.9. And at 14.7 type 15.4. Now it's smooth!

Now save this program.

Go back to the truck and hook up with the key in the RUN position. Launch EFILive Tuning Tool.

Select FLASH->Program PCM Calibrations. You will hit start, and it will say the cable is not "married" to the truck. Close the FLASH window and try again, and there will be a new button on the window to allow you to marry it.

Now do it again, and in less than 2 minutes, you will have a pretty good tow tune that is essentially just a the GM data that has been moved around a bit.
 
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LarryJewell

Back with his honey :)
Jan 21, 2007
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San Angelo
Once you have married the cable to the truck, do you have to go thru hitting the flash button/closing it out 3 times. What I mean is, if I change to a different tune, after the 1st flash, it the subsequent flashes quicker, or do I have to marry the cable everytime I do a different tune.
 

serpa4

New member
Feb 5, 2007
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Any good tow tunes, egt friendly, for LBZ? I'd like to be able to keep my foot in it when hitting the hills with 10,000 lb load.
 

bajatoy

New member
Jun 24, 2007
36
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Peoria AZ
anybody done this on a LB7 with out the big head waste gate? How does it work? Taking the toy hauler out for Labor Day and the tune I have in it now is WAY to hot to tow with, so I need to come up with a nice little tow tune
 

speedy03

New member
Nov 19, 2007
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Avon Park, FL
Thanks for the walcome! I have been driving around for a few day's now with this tune and so far i like it! The truck feels more responsive and the turbo whistle is more noticeable too. It also don't smoke! I haven't had a chance to pull a trailer with it yet but tomorrow i will.
 

tmougeotte

New member
Feb 13, 2007
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Idle issue

I am new to the efi world nut I have already built a few small tunes. I recently used the mcRat 20/20 tow tune and love it. My question is how do I smooth out my idle? Since the tune I get a looping/jumping idle. Is this normal or do I need to change something?
 

The Neens

BFD
Staff member
Aug 10, 2006
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Monrovia, Ca.
I am new to the efi world nut I have already built a few small tunes. I recently used the mcRat 20/20 tow tune and love it. My question is how do I smooth out my idle? Since the tune I get a looping/jumping idle. Is this normal or do I need to change something?
Go to tables B0720 and B0721 and enter stock values for the cells from 1-20mm3 on the left and cells 10-190 MPa on the top...See if it smoothes out...
 

02freighttrain

Team Salad Bartender
Aug 13, 2006
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sootville, Fl
Speedy, glad you made it to the diesel world. If you make a dmax run like your gasser, it gonna get interesting. Welcome.
Desoto Motorsports, Sled pull, Dec 15th. It will be a huge crowd and 40-50 Diesels. Hope to see you there. Snowbirds, come on down.
 

speedy03

New member
Nov 19, 2007
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Avon Park, FL
Speedy, glad you made it to the diesel world. If you make a dmax run like your gasser, it gonna get interesting. Welcome.
Desoto Motorsports, Sled pull, Dec 15th. It will be a huge crowd and 40-50 Diesels. Hope to see you there. Snowbirds, come on down.
Thanks! The next mod on my list is a built trans, Thats coming after Christmas. I would love to go to the sled pull on the 15th but i will be out of town. Maybe the next one.
 
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McRat

Diesel Hotrodder
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Aug 1, 2006
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www.mcratracing.com
I have to get a version written for the LMM and LBZ.

That was written back when folk were looking at EFILive and scratching their heads; the LBZ wasn't even built yet.

Honestly, it on my list of things to do.
 

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