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Tuning Question

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I have a 2014 Sierra with the 5.3L and 3:42 gears. I am currently at about 30,000kms (18,000 miles) and thinking about a tune. I think I am set on the Diablo tune and would likely go to Lew for a custom tune.


I tow a trailer throughout the summer months. This is a travel trailer that weighs approximately 7500 pounds. The truck works very hard to pull this. I will be taking a few 600 plus mile trips pulling this, but would say I pull a trailer less then 5% of miles. Since the truck is working so hard, is there a risk here going with a custom tune? I don't want to have to flip back and forth for added performance without trailer and revert back to stock with trailer?


Looking for anyone who has pulled heavy with a tune.



1. What were the differences?

2. How did the truck perform?

3. Am I worried for nothing?



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I could be wrong but i believe the tow/haul mode can be custom tuned as well. I dont have any experience towing with the tune so i cant help u there. I do remember when i loaded the can tunes it gave options to change some settings and shifts etc. on the tow/haul mode. Email Lew at diablewtunes.com he is a world of help and is very prompt with return emails.

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Nearly every truck I've owned was tuned in some manor. I can tell you that it doesn't make that much of a difference when towing. If your looking to tow "easier", then a gear swap to 3.73's would be better money spent. Your towing a pretty heavy load and pulling a brick through the wind. The custom tune really helps the 95% of the time when your not towing to make it a more pleasurable driving experience.


You can squeeze a few more HP out of the truck with a custom tune, but that will require you to run higher octane gas so you don't have any knock or ping associated with advanced timing.


A gear swap is your best but most expensive option. If you plan on towing alot of years with this truck, I'd consider it.

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A tune is a great thing to do for towing as long as it’s done well. You’re right to be a little worried, as a tune done poorly could do more harm than good—especially for towing.


The biggest worry you have is that the tune would cause a bunch of detonation eventually damaging the engine. The stock tune gets a decent amount of knock retard as-is and some armchair tuner who does a blanket timing advance increase could make things worse. But a good tune will only make things better.


You’ll want to make sure the tuner has spent a good deal of time tuning the 5.3 on a load-bearing dyno, and/or the street. The cells in the timing map that matter for towing the most are not cells you’ll even use at all on a Dynojet run, so if that’s all they have to go by they won’t be improving things much.


Anyway, there are many benefits you can get from a tune. Here are some of the things I did for mine:


Re-do main timing table, eliminating all knock retard.


Re-program shift points in Tow/Haul mode. Many complain about the factory shift points and that’s easily fixable.


Turn on the fans earlier and stronger. When towing in the summer heat is the enemy and the factory settings for the fan are way too conservative for my liking, but they do stay nice and quiet. Even with the stock thermostat you can be much more aggressive with the fans so they don’t let you get near the danger zone as easily.


If you want to do even better, adding a 180 degree thermostat (now available from Lingenfelter for $30 or so) allows you to turn the fans on even lower and harder. This drops your coolant and engine oil temp in normal cruising nearly 30 degrees giving you a much bigger cushion. Also the fans being on harder more of the time will keep your tranny temps cooler while towing (in easy cruising there’s no change due to the transmission’s separate thermostat).


And of course one of the best things you can do for towing—gears—will require a tune, as well as tire size, eliminating AFM, and about a million other little things that are nice to have done.

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