timing

[mychevyisntheavy]

how to pull timing to stop knock from happing. here is a scan of the knock. finally able to log it to show . i couldnt catch it. but have it now.25-06-10 15-20-26.hpl


here is the tune 2003.gmc.seirra.5.7.4l80e.862.small.ve.hpt i run 93 octane all the time. my engine is a 5.7 flat top pistons, 10.5-1 compression, cam is a sloopy stage 2 585/585 228/230 112*, long tube headers, tbss intake bosch injectors, 255 fuel pump. an6 lines. temps run like 180*, my plane is coming i have a set of 243 heads getting the treatment portting polishing la de da. i dont want to screw things up. so should i pull timing or desensitize. if so which is best an how much. any help would be very helpful and appreciated.

[Alvin]

Pull timing from the timing table where you see the knock start from.

You need to be careful how much you are logging. Logging too much will slow these down.

[abc]

https://www.hpacademy.com/forum/efi-...-for-feedback/

[Russ K]

Check for knock sensor DTC's. Why is the tune from a 2000 5.3 and the scan is from a 2003 V6? And it's not going into PE at WOT.

Russ Kemp

[mychevyisntheavy]

Check for knock sensor DTC's. Why is the tune from a 2000 5.3 and the scan is from a 2003 V6? And it's not going into PE at WOT.

Russ Kemp

this is a build i did adout 5 years ago. i got this truck it was a v6. blew the motor, got another motor pcm and engine harness did a bunch of mods to the engine sent the pcm of to pcmforless in ohio, keith did great for what i had at the time. i just did some more changes. and got myself mpvi3 and been learning how to tune. it runs pretty dang on good just few small issuses. i put a 4l80e trans in it. just trying to make sure i get the tune dailed in. still learning. it was a 2003 gmc, drive bye cable . and i thought i had to get the drive bye cable v8 pcm and harness. learning. wwhen i push on the pedal at speed it feels that its going in pe. i m new here to the tune world, how would tell if im in pe. like i said it feels like it goes in pe. here is and up dated tunemain.tune. 2003.5.7.4l80e.862.3.42.hpt

[mychevyisntheavy]

https://www.hpacademy.com/forum/efi-...-for-feedback/

in my carburetor & distributor days knock was just pinging. one would hear the pinging then back the distributor up. it was a fine tune thing. not hard at all. but these computer days .. omg its like you have 6 years of college just to push a button. and yes i understand people do this for a living. just not easy to no more. not usto having to ask alot when all i had to do was turn ascrew driver or tighten up a 3/8 bolts on a distributor.

[abc]

in my carburetor & distributor days knock was just pinging. one would hear the pinging then back the distributor up. it was a fine tune thing. not hard at all. but these computer days .. omg its like you have 6 years of college just to push a button. and yes i understand people do this for a living. just not easy to no more. not usto having to ask alot when all i had to do was turn ascrew driver or tighten up a 3/8 bolts on a distributor.

Knock, pinging, detonation, what ever you want to call it or if you want to get technical about it go ahead, either way, all can be inaudible to the human ear and cause premature engine failure. You can either guess at it or learn how to know for sure if it's happening or not.

[mychevyisntheavy]

[QUOTE=abc;836235]Knock, pinging, detonation, what ever you want to call it or if you want to get technical about it go ahead, either way, all can be inaudible to the human ear and cause premature engine failure. You can either guess at it or learn how to know for sure if it's happening or not.[/ what im saying is i dont hear nothing no pinging knock or anything other than the engine running smooth. if i hear it one thing but i dont. so i guess you have to rely on the pcm to tell u and id go weeks with out seeing anything. then bam check engine light scan it says knock. ok i start logging cant see it. for the longest time. then i finally got it. i understand know how to pull it out. this hptuners is great just a learning curve is all. im a old timmer. but learning

[abc]

if i hear it one thing but i dont. so i guess you have to rely on the pcm to tell u and id go weeks with out seeing anything. then bam check engine light scan it says knock.

This is the point, don't guess, especially with the Gen 3 stuff. Relying on the stock knock detection system with a modified engine and 20 year old components is a crap shoot at best. I'm like you and came from the carb. world. A big mistake I made was not studying knock detection until I started working with EFI. I'm sure I could have saved several builds years ago that had carbs. if I would have studied up on knock early on. Just because you don't hear it with your ear, doesn't mean it's not happening. As you probably know, there is usually physical signs in the combustion chamber area somewhere, but they may be so small you could miss them unless you disassemble the engine to scrutinize it.

If you running a knock limited engine/fuel combination, it's best to listen to the engine with some form of "knock ears" while you are hunting for the correct timing for the combo.