Custom tune for 1999 K1500 Suburban

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Stepside_fever95

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I'm looking at getting a tune and had a few questions.
Truck has a stock 350 with a cold air intake and 2.5" piping from cats back to dual in dual out 2.5" Jones full boar max flow exhaust.
What are the benefits of firmer shifting? What does increasing torque percentage during shifts do? How much power difference would 89 vs 87 octane tune have? What mpg gains would I see? Is it worth the money?

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Jrgunn5150

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I'm looking at getting a tune and had a few questions.
Truck has a stock 350 with a cold air intake and 2.5" piping from cats back to dual in dual out 2.5" Jones full boar max flow exhaust.

What are the benefits of firmer shifting? Some people, most people, will tell you it creates less heat, and prolongs transmission life, but really, shift time and shift firmness are not necessarily the same thing. If the shift is happening quickly and properly, there is no time for heat to build. If you want to change your shift strategy, doing it internal to the valvebody is your best bet.

What does increasing torque percentage during shifts do? No idea

How much power difference would 89 vs 87 octane tune have? 0

What mpg gains would I see? Maybe 1? not a ton

Is it worth the money? Absolutely. Most tuning is done at part throttle, and while it doesn't provide the ability to roal coal and boost you 150 rwhp, it does make the truck much more pleasurable to drive. More responsive to throttle, able to hold gear better, etc.
 

df2x4

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My tune went into a V6 truck so your experience may vary slightly, but the principles should be the same. I'll do my best to answer your questions.

1. Benefits of firmer shifting... If your transmission is built to handle it, and you've got the rear tires to put the traction down, it can mean faster track times. Other than that, not many benefits IMO. Especially in a daily driver.

2. Torque "percentage"... What you're referring to here is called "torque management," and you have the option to reduce it, not add it in. This is one ingredient to faster shifts, but it goes back to what I said earlier about your trans being built for that sort of thing. When I first got my tune, I had Black Bear Performance remove 100% of the factory torque management. A couple weeks later, my stock 4L60E grenaded during a WOT shift into second. Call it what you will, but I'd say that'd be one hell of a coincidence. I had the trans rebuilt with lots of internal upgrades, and after that the shifts were too hard for my liking. I sent my tuned PCM back to them and had the TM returned to factory and the truck still breaks traction shifting into second every time now. Like @Jrgunn5150 said, if you really want quicker shifts, trans parts are the way to go. I'm now a firm believer that the factory torque management is there for a reason.

3. Power of 89 vs 87 octane... Justin at Black Bear told me that these trucks can see very mild gains by tuning for 89, so I did it. When I sent it back to have them put the TM back in I went ahead and had them switch it back to 87 though, and to be honest I can't tell a difference at all between them. Not worth the extra fuel costs IMO.

4. MPG gains... Not going to happen in my experience. Economy will stay about the same.

5. Worth the money? Absolutely. Most noticeable thing I've done to the truck by far. Made it much more responsive and fun to drive.
 

Stepside_fever95

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Thank you guys for the input! I will leave the torque management alone then and go for an 87 octane tune.
 

df2x4

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You're welcome! I'm sure you'll enjoy it.
 

slowburb

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Leave torque management alone unless you want to replace your transmission soon. It momentarily pulls or retards timing (spark lead), essentially lessening engine output so the shift doesn't hurt the transmission.

More octane means more resistance to detonation. This affords more timing advance. A quick way to make any engine more snappy and responsive is to bump up the timing. There would be a difference between an 87 tune and an 89 tune but it would be negligible.

The factory tune is so flat that a competent tuner can make a noticeable difference just playing with the spark and fuel calibrations.
 

Stepside_fever95

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Just had a p0420 code come on today. Is this the post cat o2's that are causing this? If so would it hurt to have them to tune those out and replace the cats later?

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beardeddummy

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I would consider ridding yourself of torque management it is supposed to help the trans but the way it does it its more like when you take a weak piece of string if you just pull it tight and hold it will hold but if you pull it tight give it slack then go back tight?
 
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