04 Rcsb Silverado stock 5.3 91 octane street tune done by a local guy 3600 stall (Haven't returned after stall yet)
I just got the motor back together (burnt a hole in a #7 piston anyways used junk yard block. Re-used stock internals with new rings & Gaskets. Anyways.. I knew it was gonna have some slap (block was pretty worn) just needed it together to get back and forth to work. But I installed the 3600 stall while I had the motor out. And it feels slower now at WOT. Could the knock sensors be pulling timing because of the slap? It's a constant slap. Not just when cold. Or is the stock truck cam not big enough to benefit from a 3600 converter I'm running out of ideas. After losint races i shouldent have Any help will be greatly appreciated thanks.

 

Add octane. This will eliminate any combustion induced knock leaving you with mechanical false knock if any.

 

I'm running 93 octane in it right now. And it still feels the same.

 

Id say it just might be your tune.. i just got a junkyard 5.3 swapped into my truck, and the engine was HIGH millage out of a 2001, the engine had blown head gasket and was driven over headed until the mains seized up.. it also had pitting on the cylinders, so i honed the cylinder bores out 0.001 over service limit of 0.0032 which it took about 0.003 to make the end piston to bore clearance of around 0.004+ i used a filler gauge and the 0.004 fit easy.. so yeah.. and it has no piston slap.. iv got a video of it all if you want, just stop by my youtube below..

But, i was out tuning the VCM today for SD and noticed with the tune i had before there was no knock retard.. but now with this new junkyard rebuild there is, so as i was tuning i noticed it was because it was running TOO LEAN !

Fixed problem simply by adding fuel in the corresponding cells i was getting KR in ..

But then again this is my case.. yours is probably different.. but it would be a good place to start.. check your tune..

neways yeah man hope this helps and you figure it out and its something simple... peace

Edit: Oh and was wondering, how you brunt a hole in #7...? Thanks

 

How would you know without logging it?

 

I don't have hp tuners yet so I can't log it. And I should have the money to get it tuned about the end of the month so I'll see what my tuner says. I'm going to try my luck with hp tuners whenever it's in the budget I think it's some thing I could learn to do. Thank you for your replies!

And on #7 I'm guessing just lack of octane and too much timing had it WOT at around 5800 rpm and she finally let go. Looked like the stock rings butted and lifted a ringland.

 

 

Were you running boost or nitrous ?

I mean it looks like way lean on top of way too much timing..

and your getting KR now.. i totally would not be running your new engine on that tune.. NO WAY BIG TIME..

I mean from the looks of it no engine should have been ran on that tune..

Edit: ok just wanted to make sure i was clear here.. well let me make sure i understand first, if your local guy did your tune, someone who did it for free, dont take it back to the guy, and if your saving money to get it tuned make sure it is from a reputable shop.. please.. for the sake of your engine peace

Edit: I take that back, so as i was thinking, it could be your injector on #7 clogged up or what not.. very well could be, and if your running your new engine with that injector, bet ya your VCM could be giving KR for a reason, and it being your injector.. but i dont know any of this... im just guessing and elaborating on the scenario ..

If you are using the same injector take it out and test the flow.. i sure dont want to be saying negative things about a tuner i know nothing about besides someone burning a hole in their piston from being tuned by them.. but if number 7 injector isn't clogged up or even stuck open causing too much fuel.. id be highly suspect of the tuner..

Edit: but man that piston looks awful.. i was out tuning my 5.3 again today, though i didn't get as much KR as the day before, i did get some.. now im wanting to know just how much over timing would cause this problem Edit: as in your piston, :end Edit, i mean im getting like 2-4 degrees of KR, though im still running a bit lean in those cells, but my timing is really high for 87octane.. interesting for sure..

 

I lost number 7 on a "Street Tune" once, GM tuned um on the rich side for a reason. To keep um alive.

 

Number 7 and 8 run leaner than the others.

 

Why ?

 

The design of the intake causes more air to get forced into those cylinders. Number 7 is the worst, plus its at the rear of the engine.

 

Interesting thanks for that, i would have never known, until it was too late, though from the little research iv done in this short time, it seems more to do with the fuel inlet split or even 7 and 8 running hotter, but i can not see how the intake causes more flow to 7 or 8 than the others on a none ram air system, now maybe if boosted yeah ok i see that..

but neways yeah totally thanks man, again i would have never known.. I need to clean my injectors anyways, might as well do a flow test but yeah peace man

 

Nope it was N/A stock engine with the tune.
I'll swap out the injector tomorrow I've get 4-5 sets of stock truck injectors laying around. And a while back on the old motor I had my buddies matco scan tool hooked up to it. And it was running around 37-38 degrees at WOT but that was a couple months ago making a few 1/8th mile passes.

But I'm gonna have it returned by a more reputable guy around here. He's tuned multiple 1000whp ls cars and truck so he's more than good enough for my stock 5.3 lol

And would a bad or clogged injector throw a code?

 

Nope it was N/A stock engine with the tune.
I'll swap out the injector tomorrow I've get 4-5 sets of stock truck injectors laying around. And a while back on the old motor I had my buddies matco scan tool hooked up to it. And it was running around 37-38 degrees at WOT but that was a couple months ago making a few 1/8th mile passes.

But I'm gonna have it returned by a more reputable guy around here. He's tuned multiple 1000whp ls cars and truck so he's more than good enough for my stock 5.3 lol

And would a bad or clogged injector throw a code?

 

That is bad.

 

I pulled the plug on cylinder 7 is running way lean and is detonating bad. Plug was pretty white and pitted. Swapped the injector out for another I had off an old truck intake and it made it miss bad. Constant cylinder 7 missfire flashing CEL. Are there big enough differences in the truck injectors through the different years to make it miss like that? I didn't have any with the same part number but I put one in that was identical same plug and squirter hole patern.. should I try another injector and see? Or just park it till I can get a new set of 42#ers and convert it to e-85 and re-tune?

 

Get WOT timing to below 27 degrees.

Get actual/measured WOT AFR to 12.6.

If you change injectors then edit the IFR table.

Diagnose (find out) why #7 is misfiring.

 

Holy **** that's alot of timing, u running a Vic Jr intake with a 4 barrel tb? If ur on a stock intake manifold then ur tuner doesn't know what the **** he is doing

 

What I was thinking, when I saw your post...