Observations From Scanning My 5.3 Silverado W/hp Tuners

ShoddyHog · August 20, 2009

I've been running scans the last couple days, and it has been interesting seeing something besides an LS2 in operation...interesting and a bit shocking too.

Here's a couple things I've gathered.

1. In no way, shape, or form can I feel when AFM is engaging or disengaging. I thought I was feeling it, but I was actually feeling a "characteristic" of the 5.3 engine. A new thread will cover that sometime later.

2. AFM kicks off with very little throttle input - seems like it doesn't stay engaged long enough to be of much help. I guess it would be if you're drivng with the wind on a flat surface.

3. Though DFCO (Deceleration Fuel Cutoff) is enabled, it seems as though AFM replaces it. When you let off the throttle, AFM disables 4 cylinders, but DFCO never, ever goes active. I'm wondering if killing AFM would allow DFCO to engage, and therefore help make up for any MPG lost disabling AFM.

4. IATs stay nice and cool compared to my GTO. I wish I could get her that low.

5. Holy freakin' cow -- look at this knock retard! This knock is from only 30% throttle input on a relatively tame stock timing map. Jeez Louise.

Look at that decay rate...holy cow, GM....why don't you pull that 7 degrees of timing for an hour! lol

Knock retard is the orange line in the third graph from the top. The green line on the same graph is throttle position. As you can see on the left, it is pulling 7.5 degrees of timing. That is a LOT. Look at the "Torque Delivered" line at the top...when it pulls 7 degrees of timing, your taking a big hit in performance. I'm running a bigass cam in my goat, and at Wide Open Throttle in 4th gear I get maybe 2 degrees of KR. I don't think I put diesel fuel in it. he he

Looks like I've got some work to do Still...nothing really alarming. It could very well have moisture in the gas or something from sitting on the lot or even false knock.

cerbomark · August 20, 2009

are you doing our own tune? I d be interested to hear what you find and what you do. Thanks.

ShoddyHog · August 20, 2009

are you doing our own tune? I d be interested to hear what you find and what you do. Thanks.

I'll be doing it eventually. Right now I'll just be learning and watching. Since I have a toy to go fast, I'll be leaving it relatively tame. I don't know that I feel what everyone else feels for the lag and such. My truck seems to haul ass.

Galen · August 20, 2009

Damn, I didn't expect to see anything close to that! No wonder people are seeing better milage with higher octane gas! I would be interested to see what happens when you hook up your WBO2 sensor in it to see how lean they are running it. I need to hook up my HPTuners to mine to see if I am pulling that much timing also...sounds like a job for next week!

Galen

solarjustin · August 20, 2009

I have the ScangaugeII hooked up to my 2004 with the 4.8L and I have seen it show very high KR (30)at times. Scangauge claims it is showing how much timing it is taking out, but I don't know if I believe it can pull and add 30 that fast.

ShoddyHog · August 20, 2009

Damn, I didn't expect to see anything close to that! No wonder people are seeing better milage with higher octane gas! I would be interested to see what happens when you hook up your WBO2 sensor in it to see how lean they are running it. I need to hook up my HPTuners to mine to see if I am pulling that much timing also...sounds like a job for next week!

Galen

I probably won't be hooking up a WB02 for a while. My controller is installed deep inside my GTO, and there's no way I'm pulling it out. I'll eventually get one, but I have quite a few things on "the list" before that.

Unless you're in PE mode (Power Enrichment), the narrowband O2's along with the fuel trims will keep you at stoich (14.7 AFR), and I'm sure I wasn't in PE at 30% throttle. I'm sure what I'm seeing can be dialed down some. LS2s are known for overly sensitive knock sensors, but the guys on the GTO forum are going to crack up when they see this

Sure makes you see the value of a nice Black Bear tune, eh?

ShoddyHog · August 20, 2009

I have the ScangaugeII hooked up to my 2004 with the 4.8L and I have seen it show very high KR (30)at times. Scangauge claims it is showing how much timing it is taking out, but I don't know if I believe it can pull and add 30 that fast.

Damn...if you were pulling 30 degrees of advance, were you actually running with 10 degrees retarded? That just doesn't seem right.

Galen · August 20, 2009

I agree, I just always used my WB for all tuning since it was already hooked up. Then again, I feel my tuning skills prove that a fool with powerful tools is a powerful fool indeed!

I would love to keep track of what you are doing and how you do it so I can mirror your efforts.

Galen

Oh yea, I bought HP Tuners to tune my 04 GTO that I ended up totaling out. I am still registered over on LS1GTO.com, but never have a reason to visit over there any more. The engine/trans are now in my 98 TA.

ShoddyHog · August 20, 2009

I agree, I just always used my WB for all tuning since it was already hooked up. Then again, I feel my tuning skills prove that a fool with powerful tools is a powerful fool indeed!

I would love to keep track of what you are doing and how you do it so I can mirror your efforts.

Galen

Oh yea, I bought HP Tuners to tune my 04 GTO that I ended up totaling out. I am still registered over on LS1GTO.com, but never have a reason to visit over there any more. The engine/trans are now in my 98 TA.

As long as I don't do anything to change the cruise AFR (CAI, headers, etc.) and don't make any changes to WOT timing (throws off AFR), then I won't need a wideband just yet.

I know about the being dangerous too...I'm not a professioinal tuner. I've been tuning one LS2 for the last two years, so I've just picked up quite a bit from that.

Ghostwhite · August 20, 2009

Wish I still had my 06 M6..... traded 3 weeks ago and I still feel empty

davecast09 · August 20, 2009

interesting read... there's quite a few goat owners on here I see. Traded in my 06 for an 08 SD.

C. Charles Hahn · August 20, 2009

3. Though DFCO (Deceleration Fuel Cutoff) is enabled, it seems as though AFM replaces it. When you let off the throttle, AFM disables 4 cylinders, but DFCO never, ever goes active. I'm wondering if killing AFM would allow DFCO to engage, and therefore help make up for any MPG lost disabling AFM.

My observation has been that no, AFM being disabled doesn't affect DFCO operation.

I'm trying to remember, do you have the iron block 5.3 or the aluminum block in your new truck? Mine, with the Aluminum block, is definitely more sensitive than yours in terms of how much KR I get -- I've seen it at times pull as much as 20 degrees of timing.... which is rather amusing, watching it fall flat on its face that way

Galen · August 20, 2009

I wonder if it would help to desensitize our knock sensors. I know I have done it on my other LS1s...maybe they are too sensitive on these also.

Galen

Wasax3 · August 21, 2009

I wish there was a toggle switch in the cab for 4 to 8 cyl mode.

ShoddyHog · August 21, 2009

I wonder if it would help to desensitize our knock sensors. I know I have done it on my other LS1s...maybe they are too sensitive on these also.

Galen

I took a quick look at the settings at lunch and compared them to the LS2. The settings for attack and decay are a lot more performance killing on the truck. The question of the day, however, would be is it real knock, or false knock?

I have an iron block.

Gerry