I am looking to use universal patcher or tuner pro to tune out the downstream o2 sensors as well as the EVAP system and then write with PCM hammer via OBD Link MX+. Is it possible / easy to do this with free software or should I be using HP tuners?

I am getting the following codes with my 5.3 LM7 gen 3 swap in my G Body:
P0036 - HO2S heater control circuit bank 1 sensor 2
P0054 - HO2S heater resistance bank 1 sensor 2
P0056 - HO2S heater control circuit bank 2 sensor 2
P0060 - HO2S heater resistance bank 2 sensor 2
P0443 - EVAP system purge control valve A circuit
P0449 - EVAP system vent valve control circuit / open
P0452 - EVAP system pressure sensor / switch A circuit low

 

With a gen3 pcm, it is actually easier to make those changes with freeware than with hptuners. Hptuners just has the advantage of a more user friendly interface and quicker read/write speeds. Going deeper into tuning, freeware has more tables defined for a lot of the OS numbers than what Hptuners gives you access to. The flip side of this is that Hptuners has a far superior scanner setup that makes the actual tuning process more streamlined. They also have some custom operating systems with commercial support, whereas the freeware custom operating systems are very much more like beta software with little if any support.

 

The MX+ will work with PCM Hammer, but the ObdLink devices are probably best used for flashing on a workbench rather than in the vehicle. I've had good luck with them personally but I've heard from some people who had nothing but trouble with them. The OBDX Pro devices are the most reliable, and they also read and write 4x faster.

 

I second the idea of using an OBDX Pro and I'm certainly a big fan of Tuner Pro RT and PCM Hammer. The only possible downside to PCM hammer - and only if you do a lot of work bench programming - is that you must build yourself a harness from junk yard parts. This is not difficult to build a harness and find a three amp or larger power supply but with HP Tuners, this is much less of a concern. I don't like writing to a PCM in the vehicle due to the risks of the system voltage dropping below about 12.1 volts during a write operation.

Is your harness a red / blue connector at the PCM or a blue / green connector? The key to using Tuner Pro RT is to make certain that you get the XDF file that exactly matches the operating system (OS). If you edit the OS with an oddball mismatched XDF, your checksums will be wrong resulting in a probably unusable PCM. Maybe even turned into a wheel chock bricked and doorstop device.

Rick

 

I am using the blue / green P59 PCM. I have only accessed it in the car not on the bench using PCM hammer previously when trying to determine if I had to do a segment swap for the 4L80 trans, however after downloading the bin the car was already running the parameters for a 4L80 trans.

I checked the bin file with universal patcher and the DTC MIL for all the rear o2 sensor codes and evap codes were already turned off, which makes me wonder how is it possible my obdii would read these codes still? I’ll try erasing codes and scanning again.

Also is simply turning off the DTC MIL actually turning off the rear o2 and evap? Or do I need to go elsewhere in the software to turn it off?

 

The MIL off checkbox ONLY turns off the dash light. You have to set the code to "no error reported" if you want the code to be turned off. The MIL off feature just allows you to not be annoyed by a light for an error you already know exists, such as when you fail a MAF to run SD.

 

By simply turning off the DTC and the MIL for the rear o2 and evap system, I would assume those actual systems are still live. Is there anyway to actually turn them off from the PCM?

 

Setting them to "no error reported" turns them off. However, some people report logging an occasional brief o2 fluctuation from the cat efficiency tests even after turning off rear o2 sensors. And I have never logged the evap purge with the system off to know if the pcm is still trying to control it or not. The o2 fluctuation I refer to was not enough to be noticeable without watching it on a datalog, and the evap won't matter with it disconnected, whether it is still trying to do something or not. If you go through the full list of diagnostic codes, there are lots of things in the pcm that the factory sets to "no error reported", simply because they are unused on whichever particular platform the computer is hooked to.

 

Sorry for the noob question, but this has been bothering me for years:

When you "brick" a PCM, does that render it completely ruined, or do you just need to buy a new credit and reprogram it? Because the actual hardware inside the case is still good, right?

This is one of the reasons why I've never tried my own tuning.

 

It kinda' depends. If the PCM is merely comatose but not truly dead, you can take the lid off of a P01 or P59 PCM and ground a certain pin on the printed circuit board (PCB) while applying power to the PCM. This gives you a very brief window to upload the "kernel" program to the PCM to re-take control of the device. Sometimes, you need to do this more than once to regain control and there are a few good You Tube videos that show the correct PCB pin plus the procedures.

I don't think this works for anything newer than a P59 (around the second half of the 2007 model year) but I don't know for sure.

I am not an HP Tuners person so I can't answer that question. However, I think the "credit" is tied to the PCM hardware serial number so perhaps, you would not need a new credit. But again, IDK for sure.

Rick

 

Short of a welding accident or lightning strike, it is very difficult to accidentally damage hardware in a p01 or p59. Something as simple as a power interruption or a CAN signal at the wrong time during a full write, however, will leave the software in a state that requires the pin trick mentioned above to have any hope of rewriting to a usable state. The later gen4 computers have not had so many years of aftermarket hobbyist scrutiny, so they are much more limited in what you can get away with and not result in a doorstop.

 

If the "boot block" of the flash memory is corrupted, the pin-grounding trick won't work, but that's really rare.

There is also a way around that problem, but it requires a $75 bit of hardware and either half-dozen solder connections or a printed or CNC'd jig. This page has a few words a few links with more details: https://github.com/LegacyNsfw/PcmHacks/wiki/BDM

Far as I can tell, there are two things that make this interrupted flashes (with cause flash chip corruption) a bigger issue with PCM Hammer than with HP Tuners:

1) PCM Hammer doesn't check the voltage before it starts flashing. I've been meaning to add that feature but we have a couple of big changes in the pipeline and I don't want to rock the boat any more.

2) Bench flashing is a bit risky. And bench flashing the P01 PCMs (and some P59s) requires a pretty stout power supply, because those PCMs have flash chips that will pull about an amp when the erase a section of flash memory, and not many 12v power supplies can handle that. So the flash process starts, PCM Hammer asks the PCM to erase a section of flash memory, the flash chip pulls 10 watts or whatever, and the power supply can't keep up, voltage drops way down, and the PCM reboots... with an erased-but-not-rewritten section of flash memory. That'll be a problem with any flashing software, though.

Of course that raises the question of why bench flashing is more common with PCM Hammer than with HP Tuners or EFI Live. I have a hunch that the commercial tools are better at telling other modules in the vehicle to stay silent, but I don't know what they're doing. But I do know that if another module interrupts the flash process, that's another way to leave a PCM with corrupted flash memory.

Either way, you can usually recover with the pin-grounding trick. Most flash operations don't erase the boot block - that will only happen when changing a PCM from one OS to another.

 

I have a question somewhat in line with this one... I have a '98 PCM that is just piggybacked with a Terminator X. Basically, so I still have gauges, etc. I'm going to be swapping rear gears at some point, and I'd rather not pay a tuner for HP Tuners credits just to change the value in the box for rear end ratio. Is there any free way to get that done?

 

That would be an easy one for PCM hammer and TunerPro or Universal Patcher

 

I'm not sure that those apps can do much with a 1998 model year PCM. That would not be a P01 or a P59 device or anything later than those unless somebody swapped one in. Maybe NSFW or Gametech can chime in about that.

Rick

 

I specifically did not answer because I have no idea. NSFW is actually involved in the development of that software, so I am sure he would know.

 

The other main developer on this project (Antus at pcmhacking.net) is adding support for some additional PCMs from around the time of the P01 and P59, but it's still at an experimental stage right now. There's a list here: https://pcmhacking.net/forums/viewtopic.php?t=8827

I don't know what PCMs were used in '98 but see if you can find out that "P-number" for your PCM and then cross-reference with the ones listed in the first post.

I haven't been involved in adding support for the other PCMs, so that's everything I know.

I am working on a better UI though.