Thats correct. It has 2 timing tables. It calls them "low octane" and "high octane". The high octane table has more timing advance. A common practice of tuners is to copy the high table to the low side so as the computer shifts between the two its actually shifting to the exact same table. Its a trick to keep one single table instead of two for consistent performance. Also, the tables, both of them, are conservative. And if the high table is conservative, then you could imagine how bad the low table is. I copy the high to low then add quite a bit of timing to the part and WOT regions....big difference in throttle feel and power. I also run 93. Remember, you still have knock sensors to retard timing if they sense pinging, but I have had none so far.
6.0 what grade fuel
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Thats correct. It has 2 timing tables. It calls them "low octane" and "high octane". The high octane table has more timing advance. A common practice of tuners is to copy the high table to the low side so as the computer shifts between the two its actually shifting to the exact same table. Its a trick to keep one single table instead of two for consistent performance. Also, the tables, both of them, are conservative. And if the high table is conservative, then you could imagine how bad the low table is. I copy the high to low then add quite a bit of timing to the part and WOT regions....big difference in throttle feel and power. I also run 93. Remember, you still have knock sensors to retard timing if they sense pinging, but I have had none so far.
hoe
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If your lq9 runs on 87 then it really isn't running right... yes they can handle mixed grades stock, but the stock tune is shit. Add a real professional dyno loaded tune not any trial homebrew tunes-ers. Then: You can have a significant amount more timing and fuel added in addition with quality fuel 93+... it's a whole different engine. Then run that on 87 and feel a 10hp difference.
Lq9 has flat top pistons and more compression to take advantage. Less tolerance for bad gas.
Lq4 has dished pistons and is more forgiving to 87 oct.
Lq9 has flat top pistons and more compression to take advantage. Less tolerance for bad gas.
Lq4 has dished pistons and is more forgiving to 87 oct.
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Mechanic421
06 Denali XL
My 05 denali pings on 89 .
You don't tune for a living do you? Cause you sound foolish.
Then you need a tune up or other routine maintenance.
hoe
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I don't tune for a living. I pay a professional to do it right the first time. You sound like you think you know what you talk about.
#1taho
5150TAHO
I am in Pennsylvania this weekend and put in 87. No pinging but I notice a drop in power.
hoe
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In my 2500hd lq4 I even run 93. I notice in that truck It drinks 87 but sips 93. Considerable difference, and that's with a bone stock gm tune.
Actually all my 3 LS vehicles prefer premium. I notice a difference in all. And 1 of them is a 5.3.
In my lq9 I can notice a difference in 93 quality vs other gas stations 93. That's how sensitive they are to ocatane levels. It likes shell, chevron, texaco. Mostly gas with textron.
Actually all my 3 LS vehicles prefer premium. I notice a difference in all. And 1 of them is a 5.3.
In my lq9 I can notice a difference in 93 quality vs other gas stations 93. That's how sensitive they are to ocatane levels. It likes shell, chevron, texaco. Mostly gas with textron.
#1taho
5150TAHO
This is the first I noticed it. I normally put 89 when I come over here. 89 is more equalit to 87 back home. With 89 it's the same as home. Don't know what it is.
#1taho
5150TAHO
I also just noticed I drove 30 min after filling it and used 1/8 of a tank. That's a lot more than normal. When I leave this afternoon I will top off with 93.
hoe
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It's quality of the same grades. Compare 93 grades at different stations as well. Example... If I use bp 93 it's like 87 from a shell. 93 from bp is nothing like she'll 93.
Also to fill up with 93 vs 87 maybe a 4$ overall difference. I don't get why some people try to save that and end up refilling almost twice as fast.
Post back with your results.
Also to fill up with 93 vs 87 maybe a 4$ overall difference. I don't get why some people try to save that and end up refilling almost twice as fast.
Post back with your results.
I have 2 Blackbear Performance tunes available on my Autocal for my LQ4 - for 87 and for 89+. I ran an experiment since I wanted to know if it was worth the extra few dollars every tank to run premium. I ran several tanks on the 89+ tune with premium and there was no increase in power OR mileage. I went back to my 87 tune and regular gas, since if there's no noticeable difference I see no reason to pay more. It's fast with either tune or any octane.
That's not an accurate way to test mpg obviously. The only way to test is several full tanks, using a calculator and trip meter, and not the DIC which is only a guess. Also not all station's nozzles shut off at the same level. That station might have tripped the shutoff sooner on the nozzle.
#1taho
5150TAHO
Yeah I agree with both statements. That's why I tuned to 87. But it does seem that at some gas stations the truck burns through it faster.
You can look at your RPO codes on the label inside your glovebox. Since yours is a 2500, are you sure you don't have the 8.1l? Here's a partial list:
LQ4 14863 P ENG M ENGINE GAS, 8 CYL, 6.0L, MFI, IRON, GM 960229 E X E A
LQ5 14864 P ENG M ENGINE GAS, 4 CYL, 1.4L, MFI, OHC 940929 E 5 E A
LQ6 14865 P ENG M ENGINE GAS, 6 CYL, 3.2L, SFI, TWIN TURBO, ALUM, 60 DEGREE, GM 20109 E X E A
LQ7 14866 P ENG M ENGINE GAS, 4 CYL, 1.3L, MFI, DOHC, PORT DEACTIVATION 121 E 0 E A
LQ8 14867 P ENG M ENGINE GAS, 4 CYL, 2.0L, MFI, L4, TURBO-LOW, ALUM, DOHC, SAAB 9 2 0 E X E A
LQ9 14868 P ENG M ENGINE GAS, 8 CYL, 6.0L, MFI, IRON, GM, ** 990122 E X E A
LQA 14833 P PWO M POWER OPTION CATERPILLAR 3126, 7.2L, 207 GROSS H.P. @ 2,300 RPM 10312 E T E A
LQB 14834 P PWO M POWER OPTION DURAMAX, 7.8L, 200 GROSS HP @ 2,200 RPM 990112 E T E A
LQC 14835 P PWO M POWER OPTION DURAMAX, 7.8L, 230 GROSS HP @ 2,200 RPM 990112 E T E A
LQD 14836 P PWO M POWER OPTION GMPT V8, 8.1L, 370 NET HP @ 4,400 RPM 825 E X E A
LQE 14837 P PWO M POWER OPTION GMPT V8, 8.1L, 415 NET HP @ 5,000 RPM 825 E X E A
LQF 14838 P PWO M POWER OPTION DURAMAX, 6.6L, 300HP/860LB FT @ 2200 RPM 20610 E T E A
LQH 14840 P PWO M POWER OPTION DURAMAX, 7.8L, 275 GROSS HP @ 2,200 RPM 10904 E T E A
LQK 14843 P PWO M POWER OPTION DURAMAX, 7.2L, 190 GROSS HP @ 2,400 RPM 10312 E T E A
LQL 14844 P PWO M POWER OPTION DURAMAX, 7.2L, 210 GROSS HP @ 2,400 RPM. 10312 E T E A
LQM 14845 P PWO M POWER OPTION GMPT V8, 6.5L, 175 GROSS HP @ 2,800 RPM 980908 E T E A
LQN 14846 P PWO M POWER OPTION GMPT V8, 6.5L, 190 GROSS HP @ 2,800 RPM 980623 E T T A
LQQ 14849 P PWO M POWER OPTION GMPT V8, 8.1L, 210 NET HP @ 3,800 RPM 990112 E X E A
LQR 14850 P PWO M POWER OPTION GMPT V8, 8.1L, 225 NET HP @ 3,600 RPM 10312 E T E A
LQS 14851 P PWO M POWER OPTION DURAMAX, 7.8L, 250 GROSS HP @ 2,200 RPM HIGH TORQ 10904 E T E A
LQV 14854 P PWO M POWER OPTION CATERPILLAR 3126, 7.2L, 250 GROSS H.P. @ 2,200 RPM 980623 E T E A
LQW 14855 P PWO M POWER OPTION CATERPILLAR 3126, 7.2L, 275 GROSS H.P. @ 2,200 RPM 980623 E T E A
LQX 14856 P PWO M POWER OPTION CATERPILLAR 3126, 7.2L, 300 GROSS H.P. @ 2,200 RPM 980623 E T E A
LQY 14857 P PWO M POWER OPTION GMPT V8, 8.1L, 270 NET HP @ 3,800 RPM 981217 E
#1taho
5150TAHO
Great info.
So I did fill up with 93 on my way home. Stopped at BP. The miliage came back up and got the power back. I must have stopped at a ****** gas station and got some bad gas.
So I did fill up with 93 on my way home. Stopped at BP. The miliage came back up and got the power back. I must have stopped at a ****** gas station and got some bad gas.
It's definitely a 6.0...but i dont see anything like that in my glove. You're talking about the "Service Parts Identification" label right?
Tonyrodz
Resident Resident
Look at the sticker on your airbox under the Hood. Hopefully it's still there. It's long and silver/gray.
Yes. That list I posted is part of an RPO code list that I use to decipher RPO codes, it's not what you will see in your glovebox. If you open the glovebox, there's THIS label on the inside of the door. It's about 2" x 4" or so. All the codes in the list tell you exactly what your rig has as well as interior and exterior colors. RPO stands for Regular Production Order. I took a picture of mine so I could print it out. As you can see, mine has the LQ4 RPO.
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