stock 4.8l - cam 5.3l

[molitor]

Old 4.8l abused, plenty of power. . .plenty of noise. I have a 02 std cab-std bed silverado fleet truck. has power nothing. not even cruise control. AC rocks though. anyways, i'm swapping in a 5.3l with port and polished heads, ls6 valve springs, ls6 valves, and a modified grind 02' ls6 cam with 112 degree LSA. oh yeah, possibly, 1.75:1 ratio SS shaft rockers. My question is!

Do i need to start with a 5.3l ECM, or can i start this thing with the 4.8l ECM long enough to get one tuned?

[JHART]

Start with the 5.3 ECM.

[1978steven]

It should run, barely with the stock 4.8 ECM tuning, but you'll need to get it tuned as soon as you can.

[molitor]

It should run, barely with the stock 4.8 ECM tuning, but you'll need to get it tuned as soon as you can.

I actually live 200 feet from the only tuning shop in the area. And the guy is psyched to lay into this thing when i get it installed, he suggested i stick with the 4.8l ecm unless i can fin an 80 pin ecm with the exact same harness config. so i agree with you. thank you very much for the info. I'll learn the hard way if i must, but the easy way is so. . . .easy.

[ma.racing]

it should run keep us posted

[molitor]

so i've discovered that a replica ECM for my truck is not hard to find. PN is 12200411/HDM-12212431. anyways, its gonna cost me a whopping $34 for a salvaged box. good news if you ask me, unfortunately, the guy down the road from me says he does not do ecm only tunes, strictly dyno tunes, which is nice, but he charges $650 to tune, thats a little much for me. So, if anybody knows how to do it, i guess nelson can tune it for me. only problem is, it not just gonna be tuning a 4.8l, they are gonna have to wipe the slate clean and program it for a 5.3L. I have no idea how much i'm looking at but jeez, i'm thinking about just buying some software and doing it myself. Maybe LS1 edit or EFI-Live, not sure what to do. On top of that, my old 4.8l is running kind of rough, i hit wot to pass somebody today, and man, it really scooted, but then when i got home, it was idling rough, and not like a sensor unplugged, just a slight little flutter that progressing. I'm afraid i've got bad lifters or something to that effect, maybe a smoked piston. anyways, gonna run a compression test tommorow when i install my new servo, and maybe a vaccum test. anybody got any ideas?

[GasGuzzler]

I thought mine was expensive. Dude....

[1978steven]

I don't see why you are going to need a new ECM just because you are going from 4.8 to 5.3, it would run fine with the 4.8 tunning, for now anyway. Get with Nelson Performance and talk with Allen or shoot him a PM on here. He can set you up a tuned ECM for your truck and mail it to you, then you either send him back your stock ECM or pay the core charge and keep it, for backup.

As far as the 4.8 running poorly, it could be wires, plugs, maybe a bad coil pack, etc.... Or you could just start your 5.3 swap!

[molitor]

I don't see why you are going to need a new ECM just because you are going from 4.8 to 5.3, it would run fine with the 4.8 tunning, for now anyway. Get with Nelson Performance and talk with Allen or shoot him a PM on here. He can set you up a tuned ECM for your truck and mail it to you, then you either send him back your stock ECM or pay the core charge and keep it, for backup.

As far as the 4.8 running poorly, it could be wires, plugs, maybe a bad coil pack, etc.... Or you could just start your 5.3 swap!

I swapped in the vette servo. . . definately the cheapest and most productive mod ever, 12 bucks, 15 minutes. done. i fixed my problem with the rough idle, and i think i have even worse problems now. I ripped the dumps off my 2-out flows and ran dual tailpipes and turned them out behind the rear wheels, smoothed everything out, only problem is, back pressure problems mean valve problems. and i do have one cylinder that is particualrly noisy. as far as the tune, i just want to get another similar ECM, so when i do the swap, i'll have a programmed box already, and i don't have to sweat driving the 5.3l on the 4.8L calibration. and for 34 bucks for an ECM, i can get it and send it to nelson, and avoid hte core charge all together.

[molitor]

And the 5.3l is still miles away, needs main, cam, and rod bearings, still trying to find flat topped pistons (thinking of using 4.8l cast pistons). need moly rings, block needs to be honed, and heads need to be worked over. so far i have:

ls6 cam- cstm 112LSA
2004 5.3L longblock
stock heads
stock valves
ls6 springs
boosted oil pump
ported water pump
1.75 ratio rkrs
comp cams 7.4 pushrods(ls6 cam is gonna screw that up i'm afraid) base circle**
and waiting on OBX stainless shortys

check this out! all this so far has cost me. . . $865.73
not too shabby eh?