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  1. L31MaxExpress

    E70 Cold Start

    Fired off the van this evening. Playing with a video editor program I am considering subscribing to, so I patched together some clips of the startup and warmup. Battery is barely hanging in there and its 12F and snowing. I am actually surprised how well it started given Ethanol fuels reputation...
  2. L31MaxExpress

    Got a kick out of an old notepad

    I was recently unpacking some boxes that came from my mothers house when we moved her to the new house she bought. I found the mini spiral notebook my dad kept track of fuel ups with on the old 1983 G20 van in the late 90s and the last year of entries was after I got my license in 2001 and...
  3. L31MaxExpress

    Finally Getting Organized Correctly

    I feel a bit accomplished. Spent Friday evening and yesterday working on re-organizing. Cleaned off my tool cart, put all my most used sockets on organizer trays on top and added my most commonly used tools to it. I then put my less used tools neatly organized in my much larger box, easy to...
  4. L31MaxExpress

    4L85E mystery leak

    Now I get the fun of pulling the 4L85E. Either the input seal, pump to case or pump bolt seals are leaking. Steady drip of fluid after the engine has run for a few minutes from the converter dust shield. If it is mechanical, if it is not one thing it is another.
  5. L31MaxExpress

    New Air Cleaner Housing

    Well I can say without 100% a doubt the Spectre 4" MAF housing is garbage. The metal tube is not a problem, the cheesy thin plastic adapter warps, the metal screw inserts that hold the MAF fail and the setup becomes an unfiltered, metered air leak. I started noticing my fuel trims spiking up and...
  6. L31MaxExpress

    2004 L31

    Just thought I would show a couple images of the later L31 GM used in the GMT800 trucks. Interestingly it has both the LS and 3 bolt mounts on the side like the 8.1L but the regular old 3 bolt bosses are not all drilled and tapped. It also has its own unique casting number. The cylinder heads...
  7. L31MaxExpress

    Flowtie

    I borrowed an idea from the newer Camaros and HD Trucks. Removed the emblem and dremeled out the material behind it. Grille now has what GM calls a Flowtie and it opens right on to my transmission cooler. Should help some with transmission cooling on really hot summer days.
  8. L31MaxExpress

    L31 Distributor Cap

    So I found a cap that is not Chinese in origin. Hopefully it will hold up compared to the cheap garbage coming in from elsewhere. Merc cap vs the Delco garbage cap. The Merc cap seems to have heavier, thicker plastic than the GM garbage. This appears to be a clone of the old GM Marine cap and...
  9. L31MaxExpress

    454 TBI G30 Air Intake Hose

    Not really a GMT400 part, but hoping someone here has cut up an 88-96 G30 TBI 454 Van or Cut-Away Van based motorhome for the 454 and has one left over. Pictures for reference of what I am looking for. The small block one is half the size.
  10. L31MaxExpress

    Wrong AC pressure switch warning

    I have been fighting an issue for numerous years with my AC. I assumed it was just high head pressure cutting the compressor with a completely heat soaked interior and engine compartment in really hot weather. For years my a/c has cycled multiple times during the initial cool down and seemed...
  11. L31MaxExpress

    Electronic Fan Clutch Information

    I am reserving this thread for a writeup on the PWM controlled Trailblazer electronic fan clutch swap. I will be adding information on how to wire it and control it in the near future. The P59 controls a solid state relay that sends a PWM signal to the clutch. The clutch has a RPM feedback...
  12. L31MaxExpress

    Ordered a different cam

    Lloyd Elliot and I spent a little time going over cam options for the 383. In the end I have an Erson custom grind being made. 218/218 @ 0.050, 0.544 lift, 112 LSA and 108 ICL. Erson specs their advertised duration at a weird lift value compared to Comp, but Lloyd said it is about 275/275...
  13. L31MaxExpress

    Figured out my low rpm chug/misfiring

    It was the plug wires spacing on the OEM plug wires. Now makes me wonder if that is why it has always ran somewhat rough. I set up a set of aftermarket plug wire looms that seperated the plug wires roughly 2x the distance of the stock wires. I think the ignition wires have been getting random...
  14. L31MaxExpress

    Distributor shaft end play fail!

    I noticed my distributor making some weird noises. The rotor tip was contacting the cap electrodes, causing a clicking/tapping sound. I pulled it out and discovered I had 0.055" end play and cracked distributor cap mounting bolt holes despite the thing being aluminum. The gear had some wear...
  15. L31MaxExpress

    Fuel Contamination

    Put 93 octane in my Pathfinder yesterday evening and barely made it 1 mile home. The gas looks like pond scum. A buddy of mine shared a video of a guy that bought diesel in Illinois from 3 stations and it was all contaminated. The station I had bought "fuel" from had just been delivered 1,800...
  16. L31MaxExpress

    Very tempted

    To throw this sucker on the 383 while I have it apart changing lifters. Single plane with a 103mm TB. I have been considering 4.56s for a while too. I miss the snappy 5.13s I had in the 9.5 SF 14-bolt when I had the old 350 in the van. Honestly thinking of gearing it to make up for the low...
  17. L31MaxExpress

    1997 Express 1500 C100 Pinout

    Hopefully someone out there has one or access to one. I have spent several hours searching for the C100 diagram for my 97 1500 Express Van 5.7L. I would also like one of the underhood fuse box too, but that should be easy enough to trace out so not as concerned there. I have found and...
  18. L31MaxExpress

    Wideband Into HP Tuners

    I finally wired my AEM Wideband into my HP Tuners MPVI Pro unit for the first time ever. Now open loop tuning my VE and MAF tables. Not sure why I did not do this sooner. Well worth the time it took to add two wires and buying $10 worth of connectors on Amazon. I have it all setup in Lambda...
  19. L31MaxExpress

    L31 Extreme Budget Build

    I pulled apart the 2 bolt 880 Vortec I had at the shop this evening. It is surprisingly clean for something that sat over a year with coolant in the oil from cracked heads. I am putting this one back together with factory GM Mahle lightweight LT1 pistons and a L30 nodular iron marine crank...
  20. L31MaxExpress

    Late Model SBC and Vortec Head Bolts

    I just want to point out the mis-information that is floating around regarding the 1/2" head late model SBC head bolts used in the later TBI, Vortec and LT1 engines as well as the GM crate engines. I keep seeing people posting claims they are torque to angle but are not torque to yeild. That...
  21. L31MaxExpress

    Marine Intake

    Decided to post pone the Proflow intake and put the L31 Marine intake back on the van. This manifold was worth 20-30 hp between 5,200 and 6,000 rpm on the 350 when it cammed compared to a ported truck manifold. Will be interesting to see how the 383 responds to it. This is a place marker for...
  22. L31MaxExpress

    Real World 383 vs Built 5.3L vs Stock LQ9

    I have tuned several vehicles recently and gathered a unique comparison between 3 of them. Acceleration runs made in nearly the same weather and same section of road. Different vehicles and different engine setups. The data was pretty cool and not exactly what I expected, but HP Tuners time...
  23. L31MaxExpress

    VE Tables using MAF

    Something I have done to make VE tables less of a pain. I now tune the MAF transfer table using MAF only. Then when I am happy with the MAF calibration, I datalog and get a as much of a base VE table for a starting point. My Calculated VE, MAF fuel trims and VE fuel trims are all filtered to...
  24. L31MaxExpress

    Guys Tuning 0411s step inside

    I have had an overly rich startup since the day one on the 97. Got a little better with the 0411 swap. I recently datalogged a startup with the coolant temp in the 50s and noticed that the 0411 post startup air fuel ratio was commanded at 3.5:1 and it stayed there for about 7 seconds before...
  25. L31MaxExpress

    Intake swap thought

    Anybody have a ProFlow XT on their L31 with the stock accessory brackets? Considering pairing one with an early 8.1 DBW throttle body on my 383. Stupid GM airhat on the throttle body is costing me nearly a full second on 0-60. 97 KPA at 6,000 rpm with it removed and 88 KPA at 5,500 with it in...

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