4l60e 2008 Silverado Standard Cab 4.8l Truck Norris NSR Stock Torque Converter

[TheGizmo]

Working on tune for 4.8l that has Truck Norris NSR CAM installed. This truck does not have a traction control button and seems like the transmission is limited in first gear. I have adjusted the abuse mode in every direction and all engine torque is maxed for testing / tune but no matter what I throw at it I cannot get the rear wheel to break traction from 0 speed WOT. I am not looking for the final tune to burn the tires up but I feel I am missing power in 1st gear. After 1st gear has transitioned to 2nd gear all seems great.

I have searched and combed through the threads and tried stock abuse mode settings and everything that seems to have helped others. Am I just fighting a lost battle from the 4.8L and stock converter? I am used to working with the 6L trans and 5.3 -6.X mainly, with exception of a 2010 crew cab with 4.8 and 4L I do not recall having this problem with 1st gear. GEN4 and few GEN5

On another note if someone could point me in the direction of shift pattern types would be awesome. I have no issues taking classes or books etc on them I just would like to understand what they do to the transmission and how the TCM activates them inside and outside of tow/haul / sports modes etc. I seem to think this is the BCM that is calling the pattern selection. This would probably need to be asked in a separate thread but could my problem be just simple shift pattern selection type that is stated "it is recommended not to change these values"?

Thanks in advance I am in early stages of HP tuners and tuning in general and I am not looking for a quick fix I really want to understand all the ins and outs.

[5FDP]

Post the tune and logs.

[TheGizmo]

Added files to original post. This was the last trial I tried today. Thanks.

[blindsquirrel]

It's not pulling timing and the throttle is wide open, looks like an engine that just doesn't make any low end torque.

[blindsquirrel]

How confident are you that the cam didn't get installed one tooth off? 'Cause I don't think a cam that mild should be idling at 78kPa and only making a peak of 306lb-ft, even if it is only a 4.8L.

[TheGizmo]

From what I am learning and think I know that's how I feel. Don't get me wrong the engine feels good once it's over that low end. Plus, the owner loves the sound and the overall improvements. I personally expected more from it like I am missing something or doing something wrong. I suspect and recommended plug wires and possible plugs due that I found an insulator leaking. I swapped this with #1 so that it does not have as much area to arc to, and I have not found any more audio or visual signs of loss. However every now and then I feel I hear a skip but a slight leak in exhaust may be causing an echo at times.
As I am learning I also feel I may have missed something in the tune outside of still battling with quick coast down idle proportional / integral wants to over achieve for a moment.
Thanks for the feedback. Owner plans on new intake and injectors in the future would this make that big of a difference in low end?

[TheGizmo]

How confident are you that the cam didn't get installed one tooth off? Cause I don't think a cam that mild should be idling at 78kPa and only making a peak of 306lb-ft, even if it is only a 4.8L.

Interesting observation, I was going to ask this but the mechanic shop that did this is pretty good, just don't do EFI tunes. The wrong CAM gear was put on at first and this threw me off, first time I have seen this. A vacuum line popped, and this was pulling hot air in while heat soak was approaching that threw me off. I don't like having to go back and tell the mechanic that an issue mechanically is going on until I am certain, and I am working hard on a trust relationship between myself and mechanic team.

I think the stock is 295HP and 300lb-ft, The highest I have logged is around 331lb-ft @ 4,634 rpm 76mph. If I did math correctly this is only 292hp.

[blindsquirrel]

The only tools the ECM has to limit power like I think was your suspicion are spark & throttle, the log shows it at 2000 RPM/20* timing/99.6% throttle and just... hanging out going nowhere. Injector duty cycle is only 22%. PE is working, it's rich like it should be but doesn't look overly-rich enough to explain this (IDC is too low for it to be drowning in fuel), etc. Does not look like a tune issue to me and if it's not the tune then...

[TheGizmo]

I appreciate the feedback and looking things over. I will dig into the mechanical and see if I can find something. At this point my gut tells me what I fear is going on but I am going to do some advanced diagnostics around this just to rule it out.

I will post an update with my findings.

[TheMechanic]

Interesting observation, I was going to ask this but the mechanic shop that did this is pretty good, just don't know EFI. Although they did put the wrong CAM gear on at first and this threw me off, first time I have seen this. After this was fixed they left out vacuum line and this was pulling hot air in while heat soak was approaching that threw me off. And the fact on this type of upgrade I would always do plugs and wires for tune reasons (Just my opinion). I don't like having to go back and tell the mechanic they goofed, and I am working hard on a trust relationship between myself and mechanic team.

I think the stock is 295HP and 300lb-ft, The highest I have logged is around 331lb-ft @ 4,634 rpm 76mph. If I did math correctly this is only 292hp.

Check compression.

[TheGizmo]

Check compression.

I agree, this will probably not take place until after Monday morning but I will update the progress. I discussed this morning about some potential issues that need to be approached in a systematic way. I recommended to rule out compression and plug wires / plugs. A slight possibility the time got bumped when the cam gear was swapped, I don't know how this was approached. This was a NSR cam so springs are factory but lifters replaced. This truck did not have DOD or VVT so no mods in this area took place.

[blindsquirrel]

Admittedly, this 5.3 is very very happy about life, but it's stock other than an Ebay CAI. Yes the tiny cam (193/193) and longer arm should make more on the bottom, but shouldn't a cammed 4.8 stomp it pretty handily from peak torque on up?

LH6.hpl

[TheGizmo]

Indeed I would say very very happy about life. It has been a while since I was behind the wheel on 4.8 and never did a CAM on one until now, but I know for a fact my 2010 stock crew cab work truck with 4.8 had more bottom torque from what I can remember. I do not have a baseline for before this truck was cammed and customer states the low end is not lower than factory and the mid - top is much better. I know the peak torque is not true mainline dyno but it is math and when rpm against peak torque says lower than stock HP somethings is not quite right in my opinion.

[blindsquirrel]

Melted cats? Wonder if it would be worth checking backpressure. Usually though when that happens there is a difference bank to bank, they don't both melt down at exactly the same rate. Something to keep in your pocket.

[TheMechanic]

Melted cats? Wonder if it would be worth checking backpressure. Usually though when that happens there is a difference bank to bank, they don't both melt down at exactly the same rate. Something to keep in your pocket.

While I have a backpressure tester I really haven't used it much. I usually just pop out the HO2S's and usually that size hole give me a seat of the pants different. Along with when they are plugged you can just tell you get a LOT of gas coming out of those holes.

[blindsquirrel]

A gauge? Nobody uses a gauge. Well, approximately nobody. Maybe in youtoob videos they do.

[TheGizmo]

Sorry I may have failed to mention no cats. Owner still has B1S2 and B2S2 installed and oddly enough it actually looks like they have closer to square wave like a downstream cat would have vs close sign wave like upstream. I don't think I disabled COT protect but I have never seen the calculated cat temp go even close to threshold. The downstream is disabled though. How much of an exhaust leak will cause not enough back pressure on this mild of a cam. Could the BTR norris chop be hiding a larger leak. A known slight leak B2 around door area is going on but honestly, I can barely hear this unless I am looking for it. I would think the shop has a back pressure tester, I never think about it until I have suspicion of cats i just pull the sensor. I need to grab one just to have in my box to give a quick rule out on gauge.

The plan for tomorrow is check time, plugs and wires. I may install widebands in down stream ports just to rule out narrowband defective on up streams. This is just a way out of the box thought on narrowband every now and then I will see a huge imbalance for a extended period on STFT.

Thanks All for the super feedback, pointers tips, tricks, and help. I read tons of forums but don't usually post due to I find what I need in the archives, but I will say by far this is the best forum ever with like minds. I hope in time I will be able to help others with some knowledge and experiences of my own.

[blindsquirrel]

Single exhaust/single muffler? Just trying to find something that could be a single point of failure that would affect both banks equally.

I have seen cats come apart and go downstream and plug up the muffler, also seen baffles in the muffler come apart and cause a restriction.

[TheGizmo]

Dual exhaust/double stream glass packs shattered. factory manifold.

I was told the cam was just a performance upgrade and replaced the lifters while swapping cam. It's possible another issue was going on and owner was not aware. Hopefully the work tomorrow will shed some light on this.

[TheGizmo]

Time was checked today along with compression and back pressure "Not with my eyes, could not match schedule today". Plugs and wires did not come in time to get them installed today. It was found that the final gear has 3.23 and not 3.73 in the glove box. The ECM has 3.73 in stock calibration. I honestly did not check to see if speed matched calibration. Bluecat transmission tool matches pretty close to factory cal with 3.73 ratio. I will post some logs once I get a chance to get back to it and the plugs and wires have been changed.