4.8 vortech

[big block 88]

Is the ECM for the 1999-present 4.8 V8 truck motors supported? Does anyone have any tunes for it? We built a custom exhaust and removed the cats and I need to kill the CEL. I would like to pick up a little power also.

Thanks

Blake

[Taz]

Hello Blake,

The ’99-’07 LR4 4.8 L engines are Gen III’s – you will find useful information in the “Gen III V8 Specific” portion of this forum.

Yes, the LR4 4.8 L engines are supported by EFILive. There are numerous tunes available for download regarding these engines at www.holdencrazy.com.

The 4.8 L is the only Gen III with a 3.268 inch stroke crank (rest of the Gen III are 3.622 inch stroke) – makes it a quick revving engine. I’ve done a few swaps using this engine in lighter vehicles – works great, and they are often very inexpensive to purchase from your local auto recycler.

In a basically stock engine, there is very little performance to be gained by removing the catalytic convertors. There are many high flow cats on the market today that work well – even with modified engines. Cat technology has progressed a great deal in the last decade – removing the cats “just because” is an outdated and irresponsible approach. Unless this is a dedicated competition vehicle (permanently off road) – running cats is a sensible and responsible course of action.

Good luck with your project …..


Regards,
Taz

[big block 88]

Thanks for your responce, I know haveing no Cat's is frowned upon now a days, but this truck is primarily used in the fields and offroad/dirt road areas.

As for Holden Crazy I don't see any tunes actually lables 4.8L or LR4 it seems to be the only Gen III motor that is not listed. Unless I am missing somthing?

[Taz]

Hello Blake,

What year / model is the 4.8 L from ? What transmission are you running ? Is it 2WD or 4WD ? If you already have a PCM, what is the Service # and Hardware # on the PCM ?

Based on the answers to the above, should be able to point you in the right direction for an OEM tune and / or correct PCM for your application.


Regards,
Taz

[big block 88]

It is a 4.8 in a 2000 chevy silverado Z71 with a 5 spd manual. Our main goal is for a bit of a bump in the hp and tq, it runs great but it could be better, the fuel mileage is amazing putting around with the 5 spd. I did end up finding a stock tune for a 2006 4.8 litre so I have been tinkering with it a bit on timing tables just trying to not go to far. I would love to find someone who has built a tune already and buy from them or pay for some help.

[Taz]

Hello Blake,

Sounds like you’ve been busy ! You have some mixing & matching of components, so I have a few more questions, and I’ll try and explain why as I go.

Was the ’00 4.8 L originally installed with a standard transmission ? Did you obtain / remove the engine and transmission as a “package” ?

The reason I ask:

• ’99 - ’00 4.8 L engines used 2 different crankshafts – one for automatics, and another for standard transmissions
• standard transmission application crankshafts have a wider rear seal surface

If this combination was a package - great, no problem. If the engine was originally from an automatic, you’ll need to confirm the transmission input shaft is neither “bottoming out” nor insufficiently engaged in the pilot bearing.

You are using a tune from an ’06 4.8 L. Is this a DBC tune (Express van) or DBW tune (pickup / SUV) ?

• are you using the corresponding DBC or DBW throttle body ?
• what MAF sensor are you using ?
• van applications use a smaller MAF than pickup / SUV applications – confirm B5001 (MAF Sensor Calibration) values correspond to the MAF being used

What fuel delivery system are you using ?

• ’99 - ’03 trucks used a fuel feed and fuel return line – to / from the fuel rail
• ‘04’ - 07 used a “returnless” fuel system – just a fuel feed line, no return line
• this changes the required values of B4001 (Injector Flow Rate)
• OEM fuel systems using a return line are “manifold referenced” – FPR in the fuel rail
• in these systems a 2D graph of B4001 values looks like a straight (flat) line from left to right
• in returnless systems a 2D graph of B4001 values looks like a sloped line – from lower left to upper right

Regards,
Taz

[big block 88]

Yep the truck originally was a 5 speed 4.8 truck. It uses the fuel deivery system from the stock 00 Silverado. It is a DBW tune from the Holden Carzy library. Thanks for all your help. I know alot of people hate giving out there tuning info and that is understandable I am the same way with my duramax tunes, I am just trying to figure out how to bump up the power a bit. I am assuming you bump up the timing and ?? somthing else?

[Taz]

Hello Blake,

There is generally not much power to be gained by tuning a completely stock engine. However, you have a mix & match of components and tune, so tuning should definitely help.

With a free flowing exhaust, cylinder scavenging may improve, often accompanied by a small increase in VE. Also, with a non-stock or cold air intake, the air flow characteristics change - requiring tuning the MAF.

Obviously, a WBO sensor is required for tuning. For tuning “how to”, take a look at the “Auto VE Tuning Tutorial” and “Calc. VE Tuning Tutorial” that is included with the EFILive software package.

Given your mix and match of components, the Auto VE would be where I would start.

After the Auto VE (or several) your components should be tuned to each other, and the engine should be running well.

To tune for maximum power requires a chassis dyno. Find the minimum timing required for maximum power output throughout the RPM range. Additional timing beyond this amount will not increase power further, but may needlessly cross the knock threshold of your engine.

Examine the torque curve after each dyno run. You want the smoothest curve possible. “Dips” in the torque curve may be the result of decreased cylinder pressure. Add a little more timing in these areas, and observe changes to the torque curve on subsequent dyno runs. Monitor your AFR closely throughout the dyno tune.

Sounds like diesel tunes are your area of expertise - I know absolutely nothing about the Duramax !

Good luck …


Regards,
Taz

[GAMEOVER]

What about starting with a stock 2002 4.8 12212156 OS:
And moving this thread to GENIII section...

[Taz]

Agree ... should move this thread to the Gen III V8 Specific section ... although I have no idea how !!!


Regards,
Taz