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Tuning 2018 Chevy Silverado 5.3L HP Tuners

General Tuning Discussion

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I am having trouble tuning this truck after doing heads, stage 3 cam with phase limiter, AFM/DOD delete, Holley Hi Ram intake manifold, Katech 103mm throttle body, Kooks long tube headers plus high flow cats, and Borla cat back.

I am using HP Tuners, first i turned off all of the AFM and DOD, zeroed the variable cam tables, and turned off all associated DTCs. Then once we started the truck i re-calibrated the MAF and turned the target idle up a little. Even after turning up the target idle the truck was still trying to idle down around 500-550rpm and i noticed at idle it was lowering the ignition timing to about -10 degrees +/- 5, so i added 15 degrees to the timing base tables in about the area that the idle would be using, and that helped raise and stabilize the idle a little bit.

Now i decided to do some slow road tuning and everything felt good and the log looked ok so we decided to put it on our dyno, Its an older Dyno Jet inertia dyno we are working on make the switch to a steady state dyno, and the results were very sad. The customer was told this kit was good to make 500Hp and it barely made 20Hp over stock. the air fuel looks good, my timing is ok, and there is no Knock retard. now i am getting four DTCs that won't go away and don't know what to do about them. Feeling a little lost, don't know what i'm missing and unsure of what to do next.

I have attached a copy of the tune file, a log i took while on a test drive, a picture of the before and after dyno runs, and a picture of the DTCs. I greatly appreciate any and all help. Thank you.

Attached Files

Update to my situation, the customer is now wanting to put the stock throttle body and manifold back on. Someone else is advising him that this the right direction forward? I am not sure whats what since the advice is coming from the same people that sold him the parts. what are your thoughts and will this help with my tuning situation?

Hi Kory, first of all I apologise for the delay in replying to your post - you caught me in the middle of our UK Goodwood trip and I was very limited on time.

This isn't an engine that we typically see here in NZ so I don't have first hand experience with it but I'll do my best to help out. One of the things that stands out is the cylinder airmass is a lot lower than I'd expect for this combination - You're only seeing at best around 0.68 g/cyl where our relatively stock L98 will be in the region of 0.80-0.84 g/cyl. In short you're not seeing sufficient airflow into the engine to make 500 hp. Now the cylinder airmass is calculated from the mass airflow meter so if the calibration here is wrong then that will throw things out but without logged wideband data I can't really confirm how accurate the MAF calibration is - Your LTFTs suggest there's still some work to be done though.

There's a couple of things that may be costing you power - Firstly the target lambda is probably a bit richer than you need to be (0.80 under PE). I'd expect for this combo to be in the region of perhaps 0.87-0.88 lambda. Likewise I'd expect the engine to want a little more timing than you're currently using, particularly when you have absolutely no knock retard in the log file. Have you tried adding a little timing to test the results? Optimising the fuel and ignition further might net you a gain but I doubt its the real cause of your issues.

My gut feeling is that you've got an issue with the cam timing and this is why the engine is showing very little improvement over stock. It wasn't clear to me from your initial post but is the cam still variable (with a phase limiter), or is it now fixed timing? I notice that your Intake Cam Angle WOT table still has numbers in it and I'm just wondering if you've actually tried changing the cam angle to see the effect on power?

The other aspect with the torque based Gen V ECM is that the torque modelling can result in the ECM shutting the throttle or limiting the throttle opening. In order to see what the throttle is actually doing you need to log the correct PID and I don't know off hand which is the correct PID for your engine. Normally I log them all to start with so I can find the ones relating to accelerator position and throttle position. The PID you have labelled 'Throttle Position' is only reaching around 57% so it's definitely worth investigating. I don't want to put you on the wrong path here as you may well find that the correct PID still doesn't show 100% even when the throttle is completely open but this could easily explain your issues.