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    Fuel trim and intake air temp

    or misfire, or intake leak.... hard to tell. There's lots of things that will tell the O2 sensors that you are running lean when you aren't.. but that's what it looks like is happening.
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    My 454 Rebuild

    This is definitely the way to go. I just borrow one of our mechanics(i work in aviation) leak down tester for the night if I need one and bring it back in the same condition I got it along with a 6-er of his favorite brew. I so rarely need one that it just hasn't made sense to me to buy one...
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    Another 454 Vortec Build Thread - Documenting, Q&A, Help

    Rear O2 sensors have nothing to do with fueling. Lack of exhaust will definitely screw with the front O2 sensor readings. You need 15" or so of exhaust past the O2 sensor to keep it from reading ambient air and getting all out of whack. You probably also have an intake leak somewhere based on...
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    What is this fuse for? comes off of the positive terminal and has a wire going to the alternator.

    Is no one going to mention that the two wires shouldn't be on the same terminal? I would have thought you would have the fusible link charging wire from the alternator going to the same terminal as the main battery, then the wire going across the top of the radiator goes to the other terminal so...
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    12200411 PCM swap for 1996 to 2000 GMT400 trucks

    https://lt1swap.com/wiringharness.htm
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    Converting L29 to cop like L21 L18

    Which isn't right either... none of the GM LS stuff is COP. They are CNP (Coil Near Plug), and still use a spark plug wire that can be disconnected and replaced. Ford and dodge have used COP for many years on their V8's and V6's
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    Favorite Shop for EV6 Injector Refresh?

    It's going to be dependent on your area most likely, but I'd be really surprised if you don't have a local shop that does the refurb. Usually new is going to be in the $50-100 per injector realm. Refurb usually runs about $15-25 per injector. I use Injector Masters in Portland for my stuff...
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    Vortec 7400 FPR and Injectors Replacement

    Post a pic of them. I would assume they aren't new... generally they are used take off units that have been cleaned, flow matched, and new gaskets, seals, filters installed.
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    Converting L29 to cop like L21 L18

    I have done the conversion and bought a second hand passenger side L21 valve cover. Something to note is that the L21 used the early LS1 coils that are a different size than all the later LS coils(including the 8.1L). So you will either need to have the very hard to find early coils, or modify...
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    98 K2500 7.4L Suburban Cruise Control Cable Fix

    They were available a few years ago... I need one for my swap too, hopefully they are still made by someone.
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    Synchro NP205 Transfer Twin Stick Mod???

    https://www.gm.com/content/dam/company/no_search/heritage-archive-docs/vehicle-information-kits/chevrolet/1980-Chevrolet-Blazer.pdf You'll see by looking at the Vehicle Information Kit from GM in 1980. Only the NP205 was available and there was No available RPO option for auto locking hubs.
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    Synchro NP205 Transfer Twin Stick Mod???

    He's using the wrong terminology. Someone must have retrofitted his Blazer with Auto Locking Hubs. All 4wd trucks in 1980 came with NP205's. You could not get a full time 4wd truck in 1980. Auto locking hubs were also not an option in 1980... so none of them came synchronized.
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    Synchro NP205 Transfer Twin Stick Mod???

    Auto locking hubs didn't become an option until ~84'. All 4wd trucks in 1980 got an NP205. Mine was selectable front hubs(I still have the original spicer locking hubs on mine) and has the same cover that ORD says is for a Synchro 205(it isn't). If you still have your original figure 8 NP205...
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    Gas Mileage

    Nope, but I work with quite a few(no idea how many, because no one cares about GPA once you graduate and get your first job). I also don't work for an automotive OEM. Seems like you missed the whole point of what everyone is saying here... GPA doesn't mean much. Engineers aren't superhuman and...
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    Gas Mileage

    He's right though.. and I don't know any engineers that would be insulted by his statement. The school I went to had a 22% graduation rate for engineering tracks. You usually lost most of them in the second or third year where the real math and application courses started. "C's get degrees" is...
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    Want to Learn To Tune - Need help getting started

    I have HP tuners now because I needed it to be able to tune my 2011 Suburban, but I started with an OBDxPro VT(now discontinued and moved to the VX for the same functions plus more) https://obdxpro.com/product/obdx-pro-vx-obd2-diagnostics-and-tuning/ Using that tool, you can then use free...
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    Gas Mileage

    Since we are getting technical here... once you start going above 100mph, you actually hit a point where the amount of drag you have to intentionally create to make downforce on rear tires to have enough traction to keep moving forward surpasses the amount of drag generated from the frontal...
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    99 L29 454 build

    Yeah... that's what I said... in detail... two posts above yours. The less restriction you give the intake manifold to the outside air, the less vacuum you will see at WOT. 29 inches isn't necessarily absolute vacuum. That is a gauge measurement that would show close to absolute vacuum...
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    Another 454 Vortec Build Thread - Documenting, Q&A, Help

    All years had that. That is the line that you were asked to check and remove to verify FPR function way back in the first pages of the thread. It should be a short vacuum line running from the FPR to the back of the manifold. It is very common for it to rot out and cause a big vacuum leak among...
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    99 L29 454 build

    Volume isn't changing? How do you think an engine works? That piston moving down in the cylinder while the intake valve is open and the exhaust valve is closed is increasing the volume of the area after the throttle blade. This change in volume is what drives the pressure down(creates vacuum)...
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    99 L29 454 build

    I think you are fundamentally misunderstanding how all of this works. The entire area is hotter than ambient air. You are always going to be adding heat to the system without an intercooler or atomizing fuel. Velocity is not a part of the ideal gas law. The only reason pressure is...
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    99 L29 454 build

    No, that's not how that works. You can see from the data that the Temperature isn't even remaining constant, you are actually pumping heat into the air the entire way into the cylinder. Also, technically pressure isn't dropping. You are actually increasing the pressure in the manifold from idle...
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    Another 454 Vortec Build Thread - Documenting, Q&A, Help

    That is not the spec with the return line blocked off. As others have said... repeatedly. Those symptoms do not jive with a FPR. The second you blocked off the return line, you took it out of the equation. This is either a blocked fuel feed line(sock pickup in the tank or fuel filter that I...
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    Crank relearn and cam retard offset question

    Just make sure your CMP is good. You shouldn't need to run another one if you don't have a check engine light on. There is a procedure in this thread that supposedly will let your truck do the crank relearn on it's own. https://www.gmt400.com/threads/case-learn-or-crank-relearn.6423/
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    Another 454 Vortec Build Thread - Documenting, Q&A, Help

    Also, the return line will be the one not running through the filter.

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