2000 1500 5.3 vs 2002 Tahoe 5.3

[DodgeZ]

I have a 2000 1500 5.3. I am wanting to run a 2002 Tahoe Flex 5.3 OS/cal so I can use e-85 at a later date. Is the motor different (heads,cam, intake...) that would cause the VE tables to be different? I switched to 80lbs and it doesn't seem like I can get the cal right by adjusting just the injectors. I was assuming the air flow of the engine was the same. I don't want to mess with VE unless it is different. Also why is there a second VE table? Thanks

diff view, maybe the flex fuel OS makes the VE table this much different?
Screenshot 2023-02-19 085934.png

[kevin87turbot]

Out of curiosity, what brand injectors are they? Were they supplied with all of the characterization data? If not, you'll be chasing your tail getting them dialed in.

The original OS had a secondary VE table to reference when the MAF was failed. The later OS's just reverted to the primary VE table in that case.

There shouldn't be any issues to upgrade to the flex fuel OS. Just do a Write Entire and you'll be fine.

[2xLS1]

I have a 2000 1500 5.3. I am wanting to run a 2002 Tahoe Flex 5.3 OS/cal so I can use e-85 at a later date. Is the motor different (heads,cam, intake...) that would cause the VE tables to be different? I switched to 80lbs and it doesn't seem like I can get the cal right by adjusting just the injectors. I was assuming the air flow of the engine was the same. I don't want to mess with VE unless it is different. Also why is there a second VE table? Thanks

diff view, maybe the flex fuel OS makes the VE table this much different?
Screenshot 2023-02-19 085934.png

Kind of makes you wonder what GM Calibrators are doing with that VE table doesn't it that we don't know or understand.

[DodgeZ]

Out of curiosity, what brand injectors are they? Were they supplied with all of the characterization data? If not, you'll be chasing your tail getting them dialed in.

The original OS had a secondary VE table to reference when the MAF was failed. The later OS's just reverted to the primary VE table in that case.

There shouldn't be any issues to upgrade to the flex fuel OS. Just do a Write Entire and you'll be fine.

Cheap ebay 80lbs decaps. My buddy (famous last words) runs them and doesnt seem to have any issues. He asked if they came with a flow card as well but they didn't. How much of a difference really matters? if I change them to 79 or 81 I'd think it wouldn't be that hard to get them close. No? Some times they idle prefect at 14.7 (seems like if it is cold outside) but then sometimes it is rich when it is warm in the 13s. Starts aren't prefect but not really bad. Reving up there is a lean spike. Just makes me think something else isn't right. I also can't understand why the VE table is so different. It isn't like it is even 10% across the board, it is higher and lower. Makes me think the heads or cam isn't the same.

[blindsquirrel]

It's super easy to tune WOT with unknown injector data. The VE table just ends up with unrealistic numbers in it if the flow rate is off. You can even tweak the flow rate table to bring the WOT VE back into line. It's everywhere other than WOT where the decaps will make you want to murder somebody for ever thinking mutilating injectors to save a little money was a good idea.

[Fast4.7]

Kind of makes you wonder what GM Calibrators are doing with that VE table doesn't it that we don't know or understand.

I have seen the VE tables different in applications that share the same long block, intake manifold and exhaust manifolds. Remember any difference from the air inlet of the air box to the tip of the tail pipe is going to make a difference to VE. On the L31 350 for example a 1/2 ton truck and a 1 ton van have signifigant differences in the VE tables. The air intake system and exhaust systems are far different. Even the MAF calibrations are slightly different even though they share the same part number. Same engine in a W31 chassis has another set of data. A GMT800 L31 has a different set of data although they used the GenIII LS truck MAF. GM may also be fudging numbers here or there as well. I have seen GM manipulate injector data between applications that use the same injectors as well. A L35 4.3L uses different injector data than a L31 350 despite the injectors being the same.

Sometimes taking a MAF curve, VE table or injector data and pasting it into a tune does not always deliver expected reaults.

[2xLS1]

I have seen the VE tables different in applications that share the same long block, intake manifold and exhaust manifolds. Remember any difference from the air inlet of the air box to the tip of the tail pipe is going to make a difference to VE. On the L31 350 for example a 1/2 ton truck and a 1 ton van have signifigant differences in the VE tables. The air intake system and exhaust systems are far different. Even the MAF calibrations are slightly different even though they share the same part number. Same engine in a W31 chassis has another set of data. A GMT800 L31 has a different set of data although they used the GenIII LS truck MAF. GM may also be fudging numbers here or there as well. I have seen GM manipulate injector data between applications that use the same injectors as well. A L35 4.3L uses different injector data than a L31 350 despite the injectors being the same.

Sometimes taking a MAF curve, VE table or injector data and pasting it into a tune does not always deliver expected reaults.

But none of that is going to apply to a 00 vs 02 Tahoe except the 02 is going to be FF with different injectors. That shouldn't effect VE which is an air model. And the differences in those VEs is not slight. And I've pointed out the different injector data Vettes vs F-bodies use while sharing the same part # injectors many times here. Why so many times on completely stock vehicles when you put them in SD mode the fuel trims are no where close to 0.

[Fast4.7]

But none of that is going to apply to a 00 vs 02 Tahoe except the 02 is going to be FF with different injectors. That shouldn't effect VE which is an air model. And the differences in those VEs is not slight. And I've pointed out the different injector data Vettes vs F-bodies use while sharing the same part # injectors many times here. Why so many times on completely stock vehicles when you put them in SD mode the fuel trims are no where close to 0.

Doesn't a 2002 have a bigger cam than 2000?

[2xLS1]

No they both use the same cam. You can look it up on GMPartsdirect.
1997-2003 LM7 L59 Truck, 2003 LM4, 1999-2000 LQ4
Lift E/I .466/.457
Dur @ .050 190/191
LSA 114 (115.5 For part of 1999)
Timing 112/116 (118/113 for part of 1999)
Part Number 12560967

[DodgeZ]

It's super easy to tune WOT with unknown injector data. The VE table just ends up with unrealistic numbers in it if the flow rate is off. You can even tweak the flow rate table to bring the WOT VE back into line. It's everywhere other than WOT where the decaps will make you want to murder somebody for ever thinking mutilating injectors to save a little money was a good idea.

Do they not flow evenly? I guess if they aren't linear across the pulse widths I could see problems. I can get it to idle fine. Still not ready to hit the trails and WOT it (it is a offroad only Jeep). What are some good injectors that can handle a truck norris cam and e85?

[kevin87turbot]

Do they not flow evenly? I guess if they aren't linear across the pulse widths I could see problems. I can get it to idle fine. Still not ready to hit the trails and WOT it (it is a offroad only Jeep). What are some good injectors that can handle a truck norris cam and e85?

The 12613412 flex fuel injectors would be a great upgrade over the stock injectors and will flow 50 lb/hr. They typically cost less than $100/set and The injector data is easily found for them as well.

[Fast4.7]

No they both use the same cam. You can look it up on GMPartsdirect.
1997-2003 LM7 L59 Truck, 2003 LM4, 1999-2000 LQ4
Lift E/I .466/.457
Dur @ .050 190/191
LSA 114 (115.5 For part of 1999)
Timing 112/116 (118/113 for part of 1999)
Part Number 12560967

That must be a superceeded number. I know for a 100% fact that a 99 and possibly 2000 LM7 has a smaller cam than a 2002 LM7. Never have cared for a 4.8L or 5.3L so I have never really looked into what garbage GM put into them from the factory. Only paid attention to the 5.7L or larger. In the past 10 years I have bought 5 different iron head, long crank 6.0Ls that nobody wanted for less than $500 each and all 5 had under 150K on them. I bought a 2006 Gen 3.5 6.0L with 80K miles for $450 with a damaged timing cover and sheered off compressor mounting bosses as well. So why touch a smaller engine. Buy the iron head 6.0L, yank the heads, put $50ea junkyard 862s on it, a cam, bolt it to a 4L80E or TH400 and run the snot out of it.The early GenIIIs are absolute DOGS! They would not outrun the older 350s until GM started putting electric fans on them. 99s also had tiny injectors like 19 or 21 lb/hr from memory. Add the two variables together and you get the differences you see.

[2xLS1]

There is really no point in discussing anything with you is there? You always think you know more. And I'll repeat think.

[kevin87turbot]

That must be a superceeded number. I know for a 100% fact that a 99 and possibly 2000 LM7 has a smaller cam than a 2002 LM7. Never have cared for a 4.8L or 5.3L so I have never really looked into what garbage GM put into them from the factory. Only paid attention to the 5.7L or larger. In the past 10 years I have bought 5 different iron head, long crank 6.0Ls that nobody wanted for less than $500 each and all 5 had under 150K on them. I bought a 2006 Gen 3.5 6.0L with 80K miles for $450 with a damaged timing cover and sheered off compressor mounting bosses as well. So why touch a smaller engine. Buy the iron head 6.0L, yank the heads, put $50ea junkyard 862s on it, a cam, bolt it to a 4L80E or TH400 and run the snot out of it.The early GenIIIs are absolute DOGS! They would not outrun the older 350s until GM started putting electric fans on them. 99s also had tiny injectors like 19 or 21 lb/hr from memory. Add the two variables together and you get the differences you see.

That's incorrect. The 99 model 5.3L cam had the same duration and lift as the 2000+ models. It was on a 115.5 LS instead of 114 LS.

[kevin87turbot]

2xLS1 gave the correct information. There are several sources that confirm it. Here's another source that confirms it.

https://www.onallcylinders.com/2018/...ads-cam-specs/

[Fast4.7]

That's incorrect. The 99 model 5.3L cam had the same duration and lift as the 2000+ models. It was on a 115.5 LS instead of 114 LS.

Which makes it a smaller cam. 10 hp less from memory. 1.5* of LSA changes and valve timing events alter the overlap and thus how the engine breathes considerably.

[2xLS1]

What does a 99 model 5.3L cam have anything to do with discussing 00 and 02 differences? I'll wait.

[Fast4.7]

What does a 99 model 5.3L cam have anything to do with discussing 00 and 02 differences? I'll wait.

Because somewhere along that time frame there is a break in the production where GM shifted the cams. I have personally pulled factory 2000 year model 4.8 and 5.3L files with tuning for the smaller injectors. The smaller OE injectors are supposed to be indicative of the smaller cam. If that is the case, why did these 2000 YM calibrations have them? Hint, they had the smaller 99 cam when they were opened up despite being a 2000 year model.

[kevin87turbot]

Which makes it a smaller cam. 10 hp less from memory. 1.5* of LSA changes and valve timing events alter the overlap and thus how the engine breathes considerably.

You're correct about the hp rating. However, you're incorrect about the camshaft being a "smaller cam." As a mechanical engineer that worked at the largest aftermarket camshaft company for over 22 years, I can 100% confirm that your statement is false. If you said that the tighter LS camshaft makes more a little more cylinder pressure at low rpm, I would agree with you. Here's a good video that will help you with the basics of valve opening events.

[2xLS1]

The break in is the 99 model year. Then pose a 2000 5.3L calibration file that has 19lb injectors with correct CVNs.