K5, 5.3 swap. Help with touching up tune / knock question

[metalneverdies]

I have an 87 K5 Blazer that I have swapped in a 5.3. The motor is stock with just a free flowing exhaust going to a dynomax muffler and a 4" cold air intake.

I had the truck unlocked and set with a base "performance tune" for premium fuel. This was all before I got HP tuners and started tuning. I have touched up all the fueling that was majorly off. The truck still gets terrible MPG compared to other swaps I have read about. I know my trans pump is weak and is probably causing excessive load on the motor resulting in mpg loss.

The main reason I am posing and asking for help is I have light knock in a couple cells. I have tried the tune with 87 oct. after seeing the timing looks nearly identical to stock, so I didnt see how this was a premium only tune. After noticing I did in fact have some knock I tried it again with 91 oct. and it still has knock at the 2000 - 3200 rpm range across 55-85 map kpa cells. The reason I don't just pull timing is my 01 1500HD with 6.0 running a totally stock spark map with just some fueling fixed shows this same general area having knock. Do these motors just have a knock problem in those cells?

Please check my tune file and my data log. If you guys notice anything out of ordinary or that I could tune better I would really appreciate the input. I have it in VE tune mode right now and I have the VE table pretty much dialed in to all 1's and 0's at this point.

I just realized I cant upload my tune files on here because they are not a supported format... I can email HPT log and tune to anyone willing to help me out!

 

[bigblock72]

I have an 87 K5 Blazer that I have swapped in a 5.3. The motor is stock with just a free flowing exhaust going to a dynomax muffler and a 4" cold air intake.

I had the truck unlocked and set with a base "performance tune" for premium fuel. This was all before I got HP tuners and started tuning. I have touched up all the fueling that was majorly off. The truck still gets terrible MPG compared to other swaps I have read about. I know my trans pump is weak and is probably causing excessive load on the motor resulting in mpg loss.

The main reason I am posing and asking for help is I have light knock in a couple cells. I have tried the tune with 87 oct. after seeing the timing looks nearly identical to stock, so I didnt see how this was a premium only tune. After noticing I did in fact have some knock I tried it again with 91 oct. and it still has knock at the 2000 - 3200 rpm range across 55-85 map kpa cells. The reason I don't just pull timing is my 01 1500HD with 6.0 running a totally stock spark map with just some fueling fixed shows this same general area having knock. Do these motors just have a knock problem in those cells?

Please check my tune file and my data log. If you guys notice anything out of ordinary or that I could tune better I would really appreciate the input. I have it in VE tune mode right now and I have the VE table pretty much dialed in to all 1's and 0's at this point.

I just realized I cant upload my tune files on here because they are not a supported format... I can email HPT log and tune to anyone willing to help me out!

How much knock retard are you getting?

What is the rest of the combination?

What kind of fuel milage are you seeing?

 

[metalneverdies]

How much knock retard are you getting?

What is the rest of the combination?

What kind of fuel milage are you seeing?

Depends on the cell. But between 0 and 2 degrees or so.

What do you mean on the combination?

My 700r4 pump is going out, plus I have 3.73's and 31" tires that measure out to 29". ~5" of lift. (Yeah it looks like i skipped leg day, trying to use up tires before i upgrade) So my mpg's on premium average 11.5 to 12.5 with normal mix of driving. One time I got 17 mpg but it was mostly backroads at 45-55 mph. Puts me at like ~2300 RPM at highway speeds.

I think when I upgrade to 33" or 35" tires and a new trans my mpg will improve quite a bit. I drive a lot of highway miles to get just about anywhere.

 

[bigblock72]

2 degrees of knock retard is nothing to worry about.

Why do you think the pump is going out on the trans?

Fuel mileage goes down significantly when rpms go over 2600, 33s may actually help your mileage if you keep the lift minimal. 35s may be too tall and the bigger lift will definitely hurt fuel economy.

Try playing with the lean cruise tables and see if you can get some more out of it. Lean it out at cruise speeds and MAP (40-60 kpa) until the knock counts go to 3-4 which is usually about 15.2.

 

[metalneverdies]

Hmm, from all my other reading

2 degrees of knock retard is nothing to worry about.

Why do you think the pump is going out on the trans?

Fuel mileage goes down significantly when rpms go over 2600, 33s may actually help your mileage if you keep the lift minimal. 35s may be too tall and the bigger lift will definitely hurt fuel economy.

Try playing with the lean cruise tables and see if you can get some more out of it. Lean it out at cruise speeds and MAP (40-60 kpa) until the knock counts go to 3-4 which is usually about 15.2.

pn HPT website and ls1tech even 1 degree of retard is bad news. I guess that is only thr case on WOT?

Should I leave my dialed in VE table alone then

I know the pump is definitely weak. I installed a shift kit and TV cable kit for the 5.3 swap from Bowtie Overdrives and when I wrote down all the line pressures they had me do a few things. After diag. they informed me the trans would be safe to run, but I do have a weak trans. pump. The trans has slipped about 3 times since the swap.

I definitely plan to go with 33's at minimum. From using a gear calulator website it definitely looks like in theory I would drop rpm into the sweet spot. I am not so sure that going from an 8" wide tire to a 12.5" would keep that mpg increase.

 

[bigblock72]

1-2 degrees if knock retard isn't a big deal (especially at part throttle) unless it is continuous. If it is continuous then cut the timing in those particular cells 1 degree.

With low line pressure the 3-4 clutch pack isn't going to last long especially when you put 33s on. Be prepared.