L84 refresh with dfm delete

[Mike Edwards]

I found a great deal on a local L84 with a dead dfm lifter. I decided to go through it and keep it as a spare for my truck. It turned out to be a 2023 engine and must be fairly low mileage by the way it looked inside.

My truck is supercharged and apparently the most common failure is cracked piston ring lands. Usually that comes from tight ring gaps and butting the rings. This motor had .007” to .011” ring gaps on the top rings. For a supercharged engine they should be more like .022” so I opened them up. The second rings were already .023” or more.

I cleaned everything up and started putting it back together. I put new GM main bearings in it because the stock thrust had more wear than I liked.

Fot the dfm delete you need these solenoid plugs, a cam, lifters and lifter trays at a minimum.

In the motor currently in my truck I used an L8T cam. This is the part number.

In this backup motor I’m using an LT5 cam. Pn below.

 

[Mike Edwards]

Beyond the cam, lifters and plugs, you’ll need head gaskets, head bolts, exhaust manifold gaskets and new fuel lines. If you go with something other than an L8T cam you’ll also need valve springs. In my cases I’m using LT1/4/5 valve springs. I’m still waiting on all my gaskets, but in the meantime I’m going through the heads. Cleaning, lapping valves, new seals etc.

 

[Mike Edwards]

The short block is ready to go.

 

[PistolsFiring]

Very nice . Keep us updated.

 

[Mike Edwards]

I finally got the valve springs, head bolts and other parts in. I put the heads together. Then I realized my LT4 injectors won’t work in these 2023 heads. Up to 2022 the injectors are 7.5mm stem 23 and up they are 6mm. I paid a lot for the LT4 stuff, so the heads are going to have to go. I can reuse my 2020 heads if needed.

The old dfm lifters left some wear on 5 of the pushrods, so replaced them. The L84 uses a larger 11/32 pushrod compared to earlier motors with 5/16 pushrods.

 

[Jmzvet]

This is awesome. 99% of us will never do anything like this but appreciate those who do .
Thanks

 

[Mike Edwards]

This is awesome. 99% of us will never do anything like this but appreciate those who do .
Thanks

As the trucks get older and warranties go away or they go onto the second and third owners this will become more common.

Here is the minimum parts list required for a 5.3. I like GM parts and typically buy them through rock auto. You can always find a 5% off coupon code to take this down a bit more.

These parts I buy from BTR, there are a lot of cheap copies of the LS7 lifters and trays. This is a known authentic source for original lifters made by Delphi and quality lifter trays.

After taxes and shipping you are looking at between $900 and $1000 for parts.

You may end up needing valve and valley cover gaskets, a timing chain tensioner, spark plugs, intake gaskets etc, so it could go up.

If you want to swap a 6.2, everything is same but the cam and head gaskets. There is no cheap GM cam that works without tuning, so you'll want to source a L86/7 DOD delete cam from someone like BTR. https://briantooleyracing.com/btr-c...ab_8hNLfpOhderAOXc5e18XKyUtgilsKQ7XBL4_FHcROe

You can always choose an aftermarket cam for the 5.3 or 6.2, but more in-depth tuning will be required. I would not recommend this for anyone but an experienced tuning. These trucks and the new C8 corvettes are more involved than any previous vehicle. I'm fairly experienced and it has still taen me 6 months to fully get my supercharger dialed in.

 

[Mike Edwards]

If you do an L8T cam in a 5.3, this is what will be required to tune it. If you do anything else, you'll be tuning the neural network. That is very involved and has some minor added cost.

You'll need an HP tuners MPVI 2, 2+ or 3. You can only buy the 3 today if you don't already have a 2 or 2+.

MPVI3 OBDII Interface – HP Tuners

Introducing the latest OBDII interface from HP Tuners, the MPVI3. Check out MPVI3's new features and tuning and diagnostic capabilities. Learn more.

www.hptuners.com

You'll need to send your ecm off to HP tuners to be unlocked. Both of these links will show the cost to unlock and the required credit (@ $50 per credit)
If you have a 2019 to 2022(non refresh) truck, it should be Global A:

GM E90/E93 ECM Services – HP Tuners

Start tuning your Chevrolet Silverado & GMC Sierra truck with the E90 or E93 ECM with HP Tuners' GM E90/E93 Upgrade Services.

www.hptuners.com

2022+ (refresh) is Global B:

GM E90 ECM Service (Global B) – HP Tuners

HP Tuners is thrilled to offer custom tuning support for the GM Global B E90 ECM found in select GM vehicles (see vehicle list below). This one-time, send-in upgrade service is required to enable diagnostics and tuning capabilities. Shipping address for send-in E90 ECM service (Global B): HP...

www.hptuners.com

You'll also need the latest Beta version of their software. You much use the Beta software otherwise you'll get a connection error.

HP Tuners Software Downloads – HP Tuners

Download the latest version of HP Tuners' software, including VCM Suite BETA and stable, and MPVI & MPVI2 drivers. Download the media kit.

www.hptuners.com

Once you get the ecm back, you can plug it back in and use untuned. The truck will run as before, but you will need to do tuning after you swap the parts. So if you want to unlock the ecm before you start the DFM delete, it will be ok.

Once you're ready to tune it, you need to license your ecm. With the new unlocked ecm installed, hook up your MPVI and open the beta software. Turn the truck on with the engine off (pushbutton trucks, hold down the start button for 10 seconds with your foot off the brake). Once the dash it on, click the green "read vehicle" button.

If you don't get a connection error, you should get this popup.

Click Read. You'll get the Vehicle Reader window (shown in back, didn't get a screen shot). Your Transmission section will be greyed out unless you get your TCM unlocked also (more $$$). Hit read again and it will do it's thing and finalize with this "Tune file notice" popup. You don't actually read these ECU's, it downloads the file from an internet database somewhere.

Hit Ok and save the file with whatever name you like. Then you get back to this screen and you are ready to tune. Notice the new options available, Engine, Engine Diag, Trans etc.

 

[Mike Edwards]

I'm doing this with my already licensed truck, so I don't remember exactly at what point they ask you to license. Usually it's when you are ready to write the first tune to the truck. But this is the point where you use the credits you purchased. The license to tune is married to your specific MPVI, so if someone else wants to tune the truck they'll need your mpvi or relicense it to theirs with more credits.

This is all that is required for the basic DFM delete. You'll want to go to advanced mode under edit. Without this a lot of options aren't visible.

Then click engine

Go to the fuel tab, then lean/fuel saving.
Set Disable RPM to 0 and Variable Torque Hardware to None if you have already done the mechanical parts swap. If you want to do this all before swapping parts, just leave it as "sliding"

Now Click Engine Diag and go to the DTC's tab. For these DTC's you need to uncheck SES enable and set error mode to no error reported. These are the codes you would get from getting rid of the dfm solenoids.

That is the minimum required for the dfm delete tuning.

If you also want to turn off auto stop/start, it's under the system tabs, general. Set it to disabled.

 

[Mike Edwards]

Now you need to write that tune to the truck. Put the truck back in power on/engine off mode. Click the red write vehicle button. You'll get this popup.

Before you click write, make sure your laptop is charged and won't die during writing. Make sure the truck battery is charged so it won't die during writing. This is where you could potentially brick the ecm. Make sure your laptop is connected to the internet. I use my cell phone as a hot spot while tuning away from my house. If everything is good click write. This is where I remember getting the licensing screen, so do that if you get it.

It should take about 2 minutes two write the tune to the truck and you will probably get some errors on the dash. That is normal and they will go away. Once it's completed writing cycle the power on the truck and you should be ready to start it.


If the tuning part is intimidating to you, do this before you even get rid of the mechanical parts. You can turn off dfm this way electronically only and have that complete before swapping the parts. That way when you do swap parts and start the truck for the first time, you can focus on oil leaks and noises and not worry about the tuning.

 

[PistolsFiring]

Wow. Great write up and info for someone with the know how and desire! I’m sure this will be useful to future readers.

 

[2KWIK2C]

Wow. Great write up and info for someone with the know how and desire! I’m sure this will be useful to future readers.

I agree! Thanks and a shout out to Rock Auto!

 

[Alster]

Very impressed by @Mike Edwards ..your knowledge and application to this technology is above average on so many levels !!!

 

[Mike Edwards]

Very impressed by @Mike Edwards ..your knowledge and application to this technology is above average on so many levels !!!

Thanks! I’ve always been quite the gearhead and I’ve had some great teachers along the way.

I really wanted to use these heads because they’re in such good shape. I assume they’re very low mileage based on everything else. Like maybe under 20k. So I decided to machine the injector bores for the larger 7.5mm injectors. I can’t remember where I saw it, but someone measured an older head with a 7.75mm bore. Makes sense because the new heads are a 6.25mm bore for a 6mm injector. I’ve ordered a 7.75mm reamer. But 1.5mm is too much to ream so I’ll drill the majority out with a 19/64” (7.54mm) drill. Then I only have to ream out .009”.

I can do the work in a mill, but it was easier to be accurate with a drill jig.
Here’s the injector seat.

I machined a matching guide.

I machined a locating pin that pilots off the 6.25mm injector bore.

A little tab to locate off the fuel rail mounting boss.

And it all lines up very well.

Once the reamer gets here, I’ll make a drill bushing for it and the drill.

 

[Mike Edwards]

I have the drill so I made a bushing for it. I also made a test piece to be sure the sizing is right before drilling the heads.