LSx OBD2 Readout. Help Please

-14.8% means it is running rich and the computer is pulling fuel. You won't really get a good idea of how it is running by watching the screen as you are driving because the refresh rate on your reader will not show everything and you will not see everything due to driving. You really need to datalog it on a better scanner or HP Tuners/efi live type software.

A vacuum leak would give you positive LTFT's, as the computer would be adding fuel to compensate for the lean condition.
 
NC-V said:
-14.8% means it is running rich and the computer is pulling fuel. You won't really get a good idea of how it is running by watching the screen as you are driving because the refresh rate on your reader will not show everything and you will not see everything due to driving. You really need to datalog it on a better scanner or HP Tuners/efi live type software.

A vacuum leak would give you positive LTFT's, as the computer would be adding fuel to compensate for the lean condition.
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Hmm. So what causes a rich fuel condition? (normally)

My reader has a live data stream function. I can watch all the numbers in real time
 
My first thought is the injector scales...it'd be easier if I could see those tables, but I can't, so I can't say for sure if that's the issue or not. Otherwise, I'd think it would be something in the tuning in general.
 
Croatan_Kid said:
My first thought is the injector scales...it'd be easier if I could see those tables, but I can't, so I can't say for sure if that's the issue or not. Otherwise, I'd think it would be something in the tuning in general.
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now im kinda wishing i had purchased that efi live program... ill ping the guy that did the flash. maybe its a default deal he does and would have the numbers handy
 
Waiting on the computer guy to get back to me.

Right now looking around for fuel pressure gauge
 
It'd be worthwhile to get a live tune done. Whoever is doing it could fix everything in one shot.
 
So im at my point in tuning class about MAF. It appears maybe with it being so short and right in front of the radiator, the hotter air could be throwing off the heat element in the MAF. Which is reducing the timing unnecessarily.. Bam rich.

Also learning that water temp sensors in the head always run 8 to 15F higher. So while my gauge shows 190, and fans kicks on at 200ish, but this cooler temps advances the timing.

Learning some stuffs. Ill post what i learn as far as guess work, we'll see whats what when i get to stage of working the software.
 
Well yeah, drawing in hot air will pull timing for sure....buuuut, timing change won't effect the air fuel ratio. It may change the readings on a wideband, but not the actual air fuel ratio going in to the motor.

Edit: The ECM should be able to adjust for temperature differences unless they get outrageous. Even when my IAT tables were scaled wrong and it thought my IATs were over 140 degrees, it still wasn't running rich.
 
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Also, I don't think I ever asked, but did the ECM that you're running come with that engine and are you absolutely sure it's a 5.3? The reason I ask is it could easily be a 4.8 unless you've verified that it has dished pistons and not flat tops. If it happened to be a 4.8, that would explain all of this running rich stuff. I figure it's worth asking!
 
Croatan_Kid said:
Also, I don't think I ever asked, but did the ECM that you're running come with that engine and are you absolutely sure it's a 5.3? The reason I ask is it could easily be a 4.8 unless you've verified that it has dished pistons and not flat tops. If it happened to be a 4.8, that would explain all of this running rich stuff. I figure it's worth asking!
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LM7
 
Computer was bought separately, the appropriate color coded one and was flashed by the tuner
 
ckruzer said:
LM7
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Lm7 just refers to the generation of block and bore. 5.3/4.8 are the same except for piston. The only way to know is if you pulled it and checked the vin. Or pull the head and check the piston out. Plenty of people will pass a 4.8 off as a 5.3 to someone who doesn’t know. It’s really not a big deal unless your trying to make tons of power and tune it right.


Edit: get a cheap borescope for your phone off amazon and pull a spark plug and you will know pretty quick which it is 5.3 have a lip on the piston.


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LM7 is definitely an RPO code for a 5.3. A 4.8 would be LR4, but yes, they use the same blocks.

What heads are on it? Just curious.
 
Croatan_Kid said:
LM7 is definitely an RPO code for a 5.3. A 4.8 would be LR4, but yes, they use the same blocks.

What heads are on it? Just curious.
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Well what I was getting at is once it’s pulled and away from the vin without checking it they could say it’s a 5.3 and it really be a 4.8. I don’t think there are anyways to tell by just looking at the block. I’m pretty sure he bought it from a bigger junkyard aka not as sketchy but I’ve seen plenty of people offer up a 4.8 as a 5.3


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There's not. All of the blocks say 4.8/5.3 on them. That's why I said this :D Kinda the same way that I got sold an "LQ9" that turned out to be an LQ4, but it all worked out in the end.

Croatan_Kid said:
Also, I don't think I ever asked, but did the ECM that you're running come with that engine and are you absolutely sure it's a 5.3? The reason I ask is it could easily be a 4.8 unless you've verified that it has dished pistons and not flat tops. If it happened to be a 4.8, that would explain all of this running rich stuff. I figure it's worth asking!
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Nah, you good.
 
paperwork and pics, came from 2001 tahoe. and iirc the odds of 863 on a 4.8 are slim to none, versus 706 on either 4.8 or 5.3. could be wrong there.

ill check the pistons next time i pull a plug
 
Tahoe's were both 4.8 and 5.3, same with Silverados and Sierra's. About the closest to a gaurantee you'll find is that in every Suburban or Yukon XL, it would only be a 5.3.
 
ckruzer said:
paperwork and pics, came from 2001 tahoe. and iirc the odds of 862 on a 4.8 are slim to none, versus 706 on either 4.8 or 5.3. could be wrong there.

ill check the pistons next time i pull a plug
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You got it backwards. 862 heads came mostly on 4.8s because they've got the small intake valves. SOME 5.3s got them though. FWIW, the 4.8 was also an engine option for a 2001 Tahoe.
 
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