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HP Tuners or alternatives for MIL light

2K views 12 replies 4 participants last post by  B52bombardier1 
#1 ·
I have a LFX V6 and a 6L50e in my 66 Chevelle and have some questions about programming the ECM (e39a).
I want to eliminate or at least turn off the SES light for a few items. For example evap.
Currently my mil light is on all the time so I can’t tell if I get a new fault that really matters.
Is this something that can be fixed with HP Tuner or some other program?
To be clear, I don’t think I would like to buy HP Tuner. I would like to hire someone that owns it and knows how to use it to fix my issue.
Anyone know if I’m on the right track?
 
#2 ·
Since you have an E39 PCM, the HP Tuners alternative programs such as LS Droid, PCM Hammer and Tuner Pro RT will be of no use to you for killing off those DTC codes. Those programs are generally limited to the older P01 and P59 PCM devices.

HP Tuners or "EFI Live" will likely be your only alternative. Probably at least two credits at fifty bucks each if you do this with HP Tuners. Not sure but add the expense of a third credit if for some odd reason you have a body control module that needs to be licensed.

Rick

Sent from my SM-G965U using Tapatalk
 
#3 ·
Thanks for the response. I guess I have no idea how HP Tuners works. Can you explain the “credits”? And does EFILive have the same kind of system?
Is this something that I would need to pull/possibly ship my ECM to someone or can it be done through the OBD2 port?
Any guesses as to what someone might charge or time it would take?
 
#4 ·
I don't do HP Tuners or EFI Live but a local guy here did my first PCM in HP Tuners for fifty bucks plus two HPT credits. Not a bad deal, really. EFI Live does not do credits but is similarly priced. The catch is fewer people are skilled with EFI Live. I have since then learned the other LS Droid, PCM Hammer and Tuner Pro RT methods for the P01 PCM devices used with my LS swapped El Camino.
These are all free, zero buck activities.

Nobody recommends flashing a PCM with it installed in a vehicle. There's too great of a risk of a falling battery voltage below about 12.2 VDC to take that chance during a long OS or CAL write. If the voltage goes low during a write, you could easily wind up with an unrecoverable brick or wheel chock as your PCM. This is an expensive lesson.

Rick

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#5 ·
It occurs to me that somebody had to have ran your E39 PCM through a flash to have defeated at least VATS - Vehicle Anti Theft System - for the engine to start.

Where is that person? They would hold the current license to do things to that serial numbered E39 PCM for merely the cost of their new labor. Much less expensive.

Why didn't this same person kill off all relevant Service Engine Soon lights to begin with? Most of us keep an extensive list of trouble codes and other items to change, adapt or otherwise kill off.

Edit: And don't let any tuner "tuner lock" the operating system with whatever they do to your PCM. This is not cool and prevents others from working on your PCM.

Definitely not cool.

Rick

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#6 ·
When I was doing the swap, I sent my harness and ECM to a guy who “supposedly” modified both. It turns out he made a few mods to the harness and sent the ECM to a buddy in New York.
Both came back months later incomplete. I fixed the harness issues but had to send the ECM back to New York 2 other times. It’s still not right.
I’m not sure what was used or if it is locked but he’s not returning calls and I’m kinda done with him anyway.
I did find a local guy today who said $325 plus tokens used and to leave it in the car, he will do it through the OBD2 port. He is also trying to up sell me to a custom tune.
Your comment about the loss of 12v during programming is worrisome too. I’m not running a BCM so I don’t have any voltage control. It defaults to 13.7v. But I’m also having battery issues so I’m not sure this default is as acceptable as I was led to believe.
What can I do if it turns out the previous guy locked it?
 
#7 ·
You wrote: "What can I do if the last guy tuner locked my PCM?".

Answer: Cry big tears. It'll be a really odd looking door stop. There is a possibility you could intentionally brick it and then put it into recovery mode so that a complete write of an all new and different OS could be done. But any money you have tied up in that previous tune is gone because that tune is now gone. This is all a perilous course of action with respect to the life or death of your PCM.

Demand a thumb drive copy of your tune from the next tuner guy before you pay. That tune file is an insurance policy against situations like this.

When flashing in the vehicle (never recommended) the engine is off but the key is on. Thus, you get no alternator support for the flash, it's all about the health of your battery at that point.

This is why I have a bench OBD2 harness made of junk yard wiring, a simple switch and fuse with a three amp old Radio Shack power supply. I flash these PCM'S on the kitchen table in air conditioned comfort.

Rick

Sent from my SM-G965U using Tapatalk
 
#9 ·
A small charger usually only delivers an amp or less when you might consume nearly two amps doing a write.

I'm told the bigger chargers "pulse" their charging which isn't good for flashing either. All I know is that HP Tuners does not recommend doing any of this with the PCM in the vehicle. Some more modern vehicles than ours also have fuel pump and body control modules with other CAN bus traffic on the vehicle network that can clash with the timing of PCM flash packets and OS writing.

All in all, don't do it in a vehicle. Back in my teen years, I did "other things" in a vehicle but not anymore.

Rick

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#10 ·
I've done a number of flashes on late model mustangs (2016 and 2020), and there was no warning to not do it in the vehicle. They often advise hooking a charger up to the battery. That said, chargers often DO put out pulses. The battery should "flatten" those, much like a capacitor does. If I ever get bored enough, I'll hook an oscilloscope up to a battery with a big charger connected and see how much ripple remains.
 
#11 ·
Dennis, you can edit the tune while the ECM is in the car, as long as your battery is good, it's no problem. I'll pull over on the side of the road, change my tune, and fire it back up and roll.

I would google "dyno walnut creek CA" that will give you the phone number of dyno operators in your area. If they can't edit your tune they can probably refer you to someone that can.

Unfortunately it sounds like you got caught up in a mail order mess when putting your swap together.

*EDIT* I've always been told to NEVER run a laptop on a charger while the the battery is charging. The ground loop between the battery charger and laptop charger could run errant return current through the tuning cable/ECM and cause issues.
 
#12 ·
I can get another ECM pretty cheap. Would it be better to start over? There is no special “tune”, just bypassing the MIL for functions I don’t have and bypassing VAT.
Would it matter if the vin of the ECM and engine/trans don’t match?
 
#13 ·
VIN matching only matters in states that have very strict emissions control laws. Your age of vehicle is probably exempt anyway.

It is impossible to declare to the modern PCM that your 13-character VIN from the year 1966 is electronically valid and write-able. Since about 1980-81, all VINS worldwide have been seventeen characters.

It is always, always advisable to have a spare PCM . . . or two, three or four. Yes, it is a form of mental illness that I have but I'm getting it under control, maybe. I pick 'em up for about $18.00 on Half Price Sale Days around here. Never do these kinds of operating system re-write PCM experiments on your single good PCM. Always keep an ace in the hole PCM on the bench to get it moving again.

Rick
 
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