Topic: Knocking Issue and I'm getting fed up../UPDATE:: Problem Solved

[OLD NO.7 Avalanche]

O.K. I've been privately trying to finish this thing and after several months, I'm about ready to burn my truck and call it a day... Well here's my story..
Last year, I picked up this Av with the 5.3L and 25k on the clock and after putting on 20k more miles, I decided to put the 2.80" pulley for the S/C. But against my personal belief.I decided to have a local shop do it and tune it also (H.P tuners). well long story short,They ran the motor lean and cracked one of my pistons... .. so Now I brought an new LQ9 6.0L, before I put it in I changed the cam,springs, and I decided to have Allen Nelson set up my tune.. Well after trying several tunes and even Replacing the computer with a new one (from Him). She still is not right. With that being said, I am in no way slamming Allen,He has been great with trying to help me in this matter.and I understand that he is very buzy.I just am getting very tired in trying to nail down this problem with every couple of weeks of me sending a file and him sending another one to me . I don't want to mess with this as I'm still learning the HPT,but on the same note I would like to actually drive my truck and enjoy it.. as well as try to give Allen a break too. I can't seem to put up a file here but I can email them, So if anyone can help, by all means let me know..Thanks.
The problem I'm Having is that when I go into boost she Knocks like crazy,If I ease into the throttle,I can pretty much keep her from knocking but If i hit it she'll bog then start knocking.. on a side note ever since I put in the new computer.I have the security lock light on (only when regular starting not remote starting)but she drives so Im just thinking of pulling the light.. I'm more worried about the knock.. Any help would be great.. cause If I don't figure this soon, I'm just getting rid of it and going back to my HotRods.
Frankie#7

[Main One]

I sincerely doubt that I could figure out what Allen is having trouble with, but if you have a log where you are having the problem, email it to amber.noelthomas@comcast.net and I'll take a look at it.

[oHIobellboy]

Interesting reading here Frankie.....http://www.chevyavalancheclub.com/index.php/topic,1190.0.html   maybe this will help.

[OLD NO.7 Avalanche]

I sincerely doubt that I could figure out what Allen is having trouble with, but if you have a log where you are having the problem, email it to amber.noelthomas@comcast.net and I'll take a look at it.

I'm Emailing to you now. Thanks again #7

[OLD NO.7 Avalanche]

Interesting reading here Frankie.....http://www.chevyavalancheclub.com/index.php/topic,1190.0.html   maybe this will help.

OOOHHHH . I'm reading that now, so it looks like I have to find out how much PSI. my injectors cause that is a possibility that going to a 6.0 w/cam and S/C, these injectors may no be enough. Great find. Thanks

[oHIobellboy]

OOOHHHH . I'm reading that now, so it looks like I have to find out how much PSI. my injectors cause that is a possibility that going to a 6.0 w/cam and S/C, these injectors may no be enough. Great find. Thanks

Intimidatoruag is the one that brought it up....I just went digging as I knew we had a thread about it somewhere.

[MyBigToy]

Something else you might look into: I've read on PT.net that the MP series chargers (the lobes on the supercharger) knock with smaller pulleys and cams; IIRC, I think the cam has more to do with it than the pulley. I know that KySilverado posted in the thread I read the info in on PT.net. You could try contacting BlownChevy over there as a good resource person.

I guess I'll find out after Christmas if I have an issue with knocking...........I sure hope not.

After a real quick search, here's at least a start for you:

http://www.performancetrucks.net/forums/showthread.php?t=344756&highlight=knocking

[Main One]

Old 7,

After looking at your logs, I'd say it looks like you have an air-to-air intercooler with your IAT sensor in the stock location, or at least before the SC.  Is this correct?

[Main One]

There are 2 basic things that through a tune you could adjust to help with the knocking issue: fuel and spark.

You've probably heard it already, but it would be very beneficial to have some wideband data to go along with your log.

Without wideband data, I've tried to interpret your narrowband sensors and other data from your logs.  Compared to my non forced induction application, I thought your O2 sensor readings were a bit low under power enrichment, particularly in light of where your long-term fuel trims were at just outside of where power enrichment kicks in, in the negative teens.  Additionally, when going into power enrichment, there seemed to be a bit of rolling into enrichment.  I would suggest looking it where rpm and throttle-wise you have power enrichment kicking in, and how much fuel you are adding when you do go into enrichment.

Something that may be at work here since you seem to have less issues when under more steady-state conditions is whether your VE table is well dialed in.  I like to log not only MAF airflow, but also dynammic airflow, which is what the computer uses to get to dynamic air cylinder fill, which you logged, but I prefer to look at MAF flow and dynamic flow in a more apples-to-apples comparison.  Under most conditions, they should track pretty well.  Where they are not tracking well, you know the computer is using VE table input, which it does in transient situations.

Something to keep in mind is that the VE table "floats".  It is floated up and down via an adjustment factor to try to get a match with what the MAF is doing in steady-state conditions.  Your VE table may be pretty good in areas where you are getting knockiing, but if your engine has been operating in an area where the VE table is high relative to what the MAF is seeing, the VE adjustment factor will bring down the entire table.  When you then hit the throttle, the VE table has been floated down, and the computer will under-calculate the air going in under transient conditions until either it goes into steady-state, or you get around 4000+ rpm where the system just uses MAF input.

One more thing thing to consider in relation to power enrichment, is how much spark advance is programmed to go along with power enrichment.  You may want to scale this back some.

Finally, I am concerned whether the computer is getting good IAT data such that it can compensate by pulling timing for high IATs.  The IATs I saw in your logs were pretty consistent, but seemed to heat up when you were idling.  I suspect that you are getting the IATs from a stock MAF upstream from the SC and intercooler.  You may want to consider relocating the IAT sensor.  You can find info on doing that on the internet - I've seen some descriptions of how it was done on a GTO forum.

[OLD NO.7 Avalanche]

Old 7,

After looking at your logs, I'd say it looks like you have an air-to-air intercooler with your IAT sensor in the stock location, or at least before the SC.  Is this correct?

Sorry for the Delay (holiday is killing me) but yes you are correct. #7

[OLD NO.7 Avalanche]

There are 2 basic things that through a tune you could adjust to help with the knocking issue: fuel and spark.

You've probably heard it already, but it would be very beneficial to have some wideband data to go along with your log.

Without wideband data, I've tried to interpret your narrowband sensors and other data from your logs.  Compared to my non forced induction application, I thought your O2 sensor readings were a bit low under power enrichment, particularly in light of where your long-term fuel trims were at just outside of where power enrichment kicks in, in the negative teens.  Additionally, when going into power enrichment, there seemed to be a bit of rolling into enrichment.  I would suggest looking it where rpm and throttle-wise you have power enrichment kicking in, and how much fuel you are adding when you do go into enrichment.

Something that may be at work here since you seem to have less issues when under more steady-state conditions is whether your VE table is well dialed in.  I like to log not only MAF airflow, but also dynammic airflow, which is what the computer uses to get to dynamic air cylinder fill, which you logged, but I prefer to look at MAF flow and dynamic flow in a more apples-to-apples comparison.  Under most conditions, they should track pretty well.  Where they are not tracking well, you know the computer is using VE table input, which it does in transient situations.

Something to keep in mind is that the VE table "floats".  It is floated up and down via an adjustment factor to try to get a match with what the MAF is doing in steady-state conditions.  Your VE table may be pretty good in areas where you are getting knockiing, but if your engine has been operating in an area where the VE table is high relative to what the MAF is seeing, the VE adjustment factor will bring down the entire table.  When you then hit the throttle, the VE table has been floated down, and the computer will under-calculate the air going in under transient conditions until either it goes into steady-state, or you get around 4000+ rpm where the system just uses MAF input.

One more thing thing to consider in relation to power enrichment, is how much spark advance is programmed to go along with power enrichment.  You may want to scale this back some.

Finally, I am concerned whether the computer is getting good IAT data such that it can compensate by pulling timing for high IATs.  The IATs I saw in your logs were pretty consistent, but seemed to heat up when you were idling.  I suspect that you are getting the IATs from a stock MAF upstream from the SC and intercooler.  You may want to consider relocating the IAT sensor.  You can find info on doing that on the internet - I've seen some descriptions of how it was done on a GTO forum.

Thanks for the Input, I have a wide band (under boost she deadline at 10.0) although Idleing she will float from 13.0 to 15.6. I will look into the GTO forum. Thanks again #7

[OLD NO.7 Avalanche]

Okay Folks, Thanks to the guys at the Monster Garage, We finally found it.. Well for starters we did a smoke test and found two leaks, one was at the back of the S/C it was a hose plug with had a rubber cap.We removed that and capped it correctly, The second was the Throttle body gasket,Replaced that.. Then after taking it out for a run (she ran better but there was still the knock) So Trannyman figured on disconnecting the MAF (which in turn would automatically go to a default program),So what happens... NO KNOCK, as a matter of fact she ran excellent. .I just replaced it with a New one.. Now I'm going to give it a good run so I can give Allen a proper file to finish and I should be good. I just want to Thank everyone that chimed in on this site to give me ideas.for this. Thanks again #7

[oHIobellboy]

That's great to hear Frankie    I was afraid you wouldn't make that party if you got too much snow up there.

[MyBigToy]

Glad you got it solved and glad that it wasn't anything major.

[Troublemaker]

I got a couple pics of everyone working on the AV...   will post as soon as the camera thaws out...

[OLD NO.7 Avalanche]

That's great to hear Frankie    I was afraid you wouldn't make that party if you got too much snow up there.

I shot up there early (like 11 a.m) so the storm was behind me.It didn't start snowing up there untill 10 p.m.so we had plenty of time to fix it and get me ready for the drifting show. (man the rooster tails that she leaves is awesome) #7