No credits. No subscriptions. No mandatory donations. PCM Hammer is a FREE platform that the GM tuning community has quietly relied on for years.
With a focus on the LS platform, PCM Hammer and PCM Logger, their additional logging tool, supports VPW OBD2 protocols for tasks like full PCM flashing, calibration edits, OS updates, VIN changes, cloning modules, and data logging via J2534 pass-through devices or VPW interfaces. While the platform won't support ALL LS powered cars out there, these are engines and ECUs you're going to find in marques like Holden, Chevrolet, Pontiac, Cadillac, GMC, Buick, Vauxhall, Opel and Saab. Yes, there is an LS2 V8-powered Saab!
In short, it's a free flash tool for GM PCMs (aka ECUs) and a direct alternative to LSDroid, which we mentioned previously here.
NOTE FOR CLARITY: PCM Hammer itself is not a full calibration editor. Typically, you read the PCM with PCM Hammer, edit the resulting .bin using TunerPro or Universal Patcher with the correct XDF or another suitable editor, then use PCM Hammer to write the changes back.
What Tuning Features Does PCM Hammer Have
PCM Hammer and PCM Logger, their additional logging tool, supports VPW OBD2 protocols for tasks like full PCM flashing, calibration edits, OS updates, VIN changes, cloning modules, and data logging via J2534 pass-through devices or VPW interfaces. It also lets you make modifications such as VATS removal, DTC disabling, and of course, performance tweaks by way of tuning your car.
- Works via the OBD-II port using a compatible interface (list below)
- Can be used bench-top or in-vehicle: does not always require removing or opening the PCM
- Reads and writes the full calibration region, which can then be edited in tools like TunerPro, Universal Patcher, or a hex editor
- Smart write: PCM Hammer compares your modified file against what's already on the PCM and only rewrites changed sections, saving significant time, a small calibration change can flash in under a minute rather than requiring a full write
- Read times vary significantly depending on the interface used. With OBDX devices, a 512KB PCM can be read much faster than with an OBDLink device, while OBDLink devices can take around 30 minutes for a full 512KB read, longer with the SX
- Primarily targets P01 and P59 PCMs found in 1999–2007 GM vehicles, though support has expanded over time
- Open-source! Code is available on GitHub, maintained by community contributors (perhaps you too one day)
What PCM Hammer Is Not
PCM Hammer is not a full commercial tuning suite like HP Tuners, Hondata, or PCMTec. Similar to other low-cost or community developed tools such as LSDroid and ECUFlash, it doesn't have a built-in calibration editor. It's purely a flash tool. PCM Hammer is used in combination with a separate editor, like TunerPro, and a self-sourced definition file to actually make tuning changes.
None of that has to be a deal breaker; it is just good to set your expectations before you dive into platforms like this, as they do require a bit of effort to reap the affordability rewards they offer.
Can PCM Hammer Help With Engine Swaps?
Yes, provided you're working with a supported GM PCM, PCM Hammer can be useful for LS and other GM engine swap projects. It allows you to read and back up the PCM, write a suitable calibration or operating system, clone compatible modules, change VIN information where supported, and flash changes back to the PCM once those changes have been made in the correct external tuning software.
That can make it useful for the common engine swap jobs like as VATS removal, matching the PCM to the transmission being used, adjusting fan control, disabling irrelevant diagnostic trouble codes, and getting a donor engine and PCM combination closer to what your swapped vehicle actually needs.
Is PCM Hammer Free?
While PCM Hammer itself is free, there are still other direct costs involved with tuning your own vehicle. In this case these costs are:
- A physical interface tool
- More of your spare time
- Limited or no technical support
- A tuning laptop
- XDF definition file (you can find many for free, but not all)
When compared to commercial reflash tuning software like HP Tuners, PCM Hammer is less refined, will take you longer to understand, and the wait time for flashing your ECU is generally longer. HP Tuners also allows real-time tuning on some LS platforms, while PCM Hammer follows a more traditional read, edit, and write workflow.
That won't be a deal breaker for many people, and these are pretty much the generic trade-offs for any open source tuning project.
What ECUs Can PCM Hammer Tune?
At the time of writing PCM Hammer and tools support reading, writing, and data logging with General Motors P01, P04, P05 (VPW), P08, P10, P11, P12, P59, 4 connector 98-02 Black Box and E54 PCMs.
How To Download PCM Hammer
Get the latest release via the official PCM Hammer website and follow the current GitHub/forum release guidance; extract the ZIP and run PcmHammer.exe. Easy!
You can also get it from the Microsoft Store, as well as the PCM Hacking forum, which is also where you can find many XDF definition files and community support.
Like most reflash tuning software, PCM Hammer is Windows OS only. A tuning laptop doesn't need to be very powerful so if you are a Mac user, your wallet isn't going to get too hammered.
What Interface Tools Work With PCM Hammer?
The documentation from PCM Hammer gives a fantastic rundown on tools they have tested. Here are the key options:
OBDX Pro (Recommended)
The original OBDX Pro VT was built by two PCM Hammer collaborators with the goal of matching an AVT or J2534 device's speed and performance, but at the lower price point of an OBDLink. Since then, they've created even more options, and the VT, VX, or GT will all work well.
We do strongly recommend using an OBDX device where possible. It's an easy way to give back to the community that has worked to create this platform for us all, and it helps that they're also great interface tools.
OBDLink Devices (LX, MX+, SX)
All three are supported, but none of them support high-speed 4X communications. That means a full read of a 512KB PCM will take around 30 minutes, longer with the SX. At that duration, connecting a battery tender is a sensible precaution. A few things to note:
- The LX is the preferred option in this range. It uses Bluetooth and has proven reliable.
- The MX+ is supported. Note: the MX (without the Plus) is not supported.
- The SX uses USB, is the most affordable option, but is also the slowest.
These devices are inexpensive and readily available from many different sources.
AVT 852
Fully supported and high-speed capable. The only real drawback is the comparative cost to some other options.
J2534 Devices - (Don't bother)
In theory, any J2534-compatible device should work. In practice, there can be conflicts between some J2534 device drivers and the Windows Store version of PCM Hammer. If you're using a J2534 device and running into issues, download PCM Hammer via the .zip release instead. If you already happen to own a VCX Nano or Bosch MDI2, they can be worth trying before buying another interface, but if you're buying specifically for PCM Hammer, we'd still point you towards OBDX Pro first.
So, Is PCM Hammer Worth Using?
PCM Hammer is well-regarded in the GM tuning community as a cost-effective alternative to commercial tools for supported platforms. For those with a bit of confidence on their computer keyboard and an unmodified or mildly modified build, this is a great option. What you save in money you pay in time, but the community has done a great job on getting this to where it is today.
That said, being hobbyist-developed software, you need to test cautiously to avoid bricking PCMs and to give you the best chance of success. Also, use the recommended tool, not just the cheapest piece of crap you can find.
If you want to learn how to tune a GM LS V8 using platforms like PCM Hammer, check out the next free tuning lesson. While HP Tuners is used for the demonstration, you're doing all the same things and all your changes have the same impact when you have PCM Hammer on your screen instead too.
