engine tuning - was i overthinking it that much?

some shall recall the tale of the 9-7x 5.3i AKA Carli's daily driver. the week before the challenge the engine started knocking, presumably from a DOD related part failure as pretty much any of them end up doing, many having done so during the warranty period. after exhaustive research, i found that the 07-09 LY2 4.8 would swap in with the correct crank sensor reluctor(58x versus 24x for older engines) and has no DOD or VVT. sourced one for $1500 with 48k and had it shipped from minnesota only to find that they had mis labeled the auction and it was actually 1 year older and a 24x engine, so it had to go back. then i found an 09 silverado rolled into a ditch in PA that had 59k and ran, and the junkyard pulled the engine for me while i headed out to get it.

many pains in butt later(never do an engine swap on a gmt360, i beg you, learn from my mistake) we installed it, and i knew i would to tune out the DOD portion of the program. to make sure the engine was good before my 30 day junkyard warranty ran out, i started it up and it revved very sluggish and had no power, but otherwise ran with no noises like one would expect a low mile engine to do. i chalked the poor running up to the computer being for a 5.3 and the engine being slightly smalled. i have HPTuners, so i proceed to pull the stock program, delete the DOD, and change out every fuel and spark table for the ones from an LY2 computer. most are very close but not exact, some are way different(like thousanths instead of tenths different) but i do it anyway. idle is all over the freaking place but it revs quick. also, exhaust leak. weeks go by as work occupies time, i get to the end of my rope and call a shop. $100 and 1 day it'll be perfect. call them today, it's now $450 and they can't guarantee anything earlier than next thursday but it'll have to sit there in case they get something else done early, with my laptop and cable, or else it's $100 more for 2 tuning credits. at this point i'm figuring what the heck do i have to lose. pulled manifold, my buddy put the exhaust gasket on upside down. hosed it with copper seal and put it back the right way, no leak. input all the original idle tables to the program, go around block. trans shifts too hard, i get the reduced engine power light, can't go over 15, and am almost run down by an shiny happy person in a big work van who didn't understand that 4 way flashers and a vehicle going 15 was probably not going to go any faster and that he should probably refrain from laying on the horn, riding my bumper, and flipping me off until i get to my driveway.

lightbulb. i write the 100% stock tune back to verify. same thing, super slow revs, so i wonder "hey moron what if the lack of revs is from the DOD not being there anymore!" i delete JUST the DOD and it's trouble codes, write it, and the bastard runs just like it did before any of the bad happened. drive around block, feels exactly like it should, no SES light. I'd heard in the past that 4.8/5.3 run fine on each other's programming, but not one time before i spent hours changing graphs and tables in the program did I think to just try deleting the one difference and running it. heck i'm running the 5.3 in the impala on a stock 5.7 LS1 tune and it runs perfect.

i guess it's time for a real test drive, more than around the block, but i think i overthought the entire thing, and it may just have been that easy.

DOD?

In reply to alfadriver:

Displacement on Demand

alfadriver wrote: DOD?

I'm guessing cylinder deactivation.

Edit: got beat

They had that on the 5.3? Didn't know that. I know it's on the 6.2. edit- we call it VDE, and I can't remember how I heard GM's nomenclature recently- so I didn't even think of displacement on demand.

Interesting.

In terms of how similar engines run to each other- a lot of that has to do with how similar they are mechanically- port, valves, timing, CR, etc. The closer those are, the closer spark will be. Fuel- that depends on the starting point.

Still, I have found a lot of times that starting with what seems to be an unrelated engine, it runs pretty well right off the bat. When the non-dimensional stuff is calibrated correctly- it's a lot easier to have a calibration that applies to a lot of stuff.

Technically it won't be right because the timing is based on grams/cycle rather than MAP, but if it runs good it runs good...

well, technically it's close enough for me right now. i drove it around the block 2 more times, then to lowe's, then dropped it off at her work and picked up my truck. ran perfect, no engine light. 35 miles is a good test drive, i drove the datsun 5 miles then took it to the challenge. i'm guessing i could take the maf flow to timing correction tables from a similar 4.8 and plug them in and get it even closer, but for now i'm considering this a major victory. BTW the shop guy never did call me back, he was supposed to check and see who told me $100 and if that offer still stood.

also, forgot how much fun it is to drive for a truck based vehicle. the snaab engineers did a nice job dialing in the suspension.

i think technically the gm stuff of this era is AFM - active fuel management, but hptuners refers to it as displacement on demand.

also, saab out of garage? impala time! pulling the heads and if the block looks ok, ls6 heads/cam on the 5.3 if not i'm going to summit and buying an ls2 block and building a monster.

MAF based makes it a whole lot more transferable. Measures mass, and delivers mass. Did you keep the 5.3 injectors (or are they the same)?

Gm pushed the easy button, 4.8-6.0 trucks have the same injectors.