HP Tuners is a powerful editing tool for the GM E38 ECM. I cannot think of anything that can't be adjusted. Some of the computations and lookup values are a little abstract but a simple google usually tells me what the acronym means, and the dimensions tell me what is being modified. THE SINGLE BIGEST PROBLEM THAT I RUN INTO TIME AFTER TIME IS THERE IS NO LOGIC AVAILABLE. A couple of examples: I have my fan settings exactly per stage and percentage and they should work when I heat the temperature sender to well over 230 degrees F. If I knew the program logic, I could see something like an AC MIL preventing them from working. As is I have no idea what is preventing my fans from operating. Another example, I deleted VATS, followed instructions exactly. For two weeks I insisted that I deleted VATS. When I tried to start the engine, it acted exactly like VATS was operational. With no logic available it was by chance that someone told me to look at and eliminate starter diagnosis in two places. How and where does one get a logic diagram for all this programming we can alter? How does one know if you change something it affects or prevents something else? My fans as an example, assuming my wiring is right, my stages are right, my percentage tables are right, everything fan is right, Based on program logic what has the ability to prevent fans from working? Sorry for the RANT but it is still my biggest problem with this tuning stuff.
Firstly, if you actually want help - you must post your most recent tune.
Secondly, just because you can purchase software, does not mean that its use is intuitive.
Most people never get beyond the basic functionality of Word or Excel (Microsoft Office), as these skills must be learned - via instructional books, videos, or formal classes.
Using HP Tuners software (or any tuning software) is no different.
This is why some people opt for a professional tune - as they do not have the time, or the inclination, to invest the hours required in the self education process.
I have been using tuning software on a daily basis for two decades. From time to time I still learn something new - as it is quite difficult to know absolutely everything about any software and / or the tuning process.
Points all well taken. I bought HP tuners to get me to a professional tuner. My first reason was to get past VATS. My rant touches on that problem where there was more to it than just running a couple of patches. My second reason was to get the car running and idling with an aftermarket cam. I may have done that with raising rpms and air adjustments. I am now trying to get the car to cool. Once past this I am taking it to a professional tune over in Pearland. The word is he may know almost as much about this stuff as you. Meanwhile, what do I need to do to make the ECMs control the fans? As you suggest, take a look at my data and provide me with any help you can.
By the way my engine is a 2008 genIV L92 with VVT deleted, an LS3 intake and a mild cam. The E38 ECU is the one that came from the salvage yard with the engine. Both ECUs Porsche and GM have their own temperature senders on the LS. The Porsche is in total control of the air conditioner. The LS has no interface with the AC.
with the fan settings go back to stock and then what do u want to do just lower the enable temps so fan low and then fan high are on sooner ? also go into the scanner and command the fan1 on and fan2 on and fan3 on make sure it triggers them, i think fan 3 is a/c controlled fan and other two and low and high engine fan
The reason the fan settings are changed is because stock settings did not work. With the scanner I "can" turn on, turn off high and low fans. I have no air conditioner and no third fan. If it helps, see my wiring diagram attached to my earlier message.
leave the state v desired as stock that is just the trigger point for the desired v fan % on the way up in temp and down in temp, the state v desired value 50 is a set point once the desired % gets to the 51 it should trigger the fan on, then same with the 90 on is triggered by the 91 value it has to go over the desired to turn on, then on the way back down its opposite, desired fan 1-0 is 25 so the desired % lowest temp is 24 so that should turn the fan off, hope that helps a little see how these settings go, if u set the lowest fan temp to 51 it should stay on once its up to temp as a test
Using the scanner, is the E38 ECM calculated vehicle speed always at the maximum - even when the vehicle is stationary ?
It appears that someone has attempted to modify the E38 ECM calibration from the original use with a 6L80, to use with a manual transmission. There are many more parameters that need to be changed for this to actually work - and several are not available in HPT.
The best option is to use an actual manual transmission calibration.
If the ECM "thinks" that the vehicle is travelling at a very high rate of speed, it may never turn on the electric radiator cooling fans.
This engine came from a car with an automatic transmission. I was allowed to edit the transmission to be manual. I can restore the automatic setting if it will help.
I do not yet understand the process of getting and using an actual manual transmission calibration.
Using the scanner, the E38 shows 158 MPH. I do not know how the program arrives at this. I have not yet moved the car so I do not know what happens in motion.
The tuning says that the fan % adjustment diminishes to the setting I have of 512 MPH 158 is a long way from 512.
You help is appreciated more than you know. Thank you very much for taking an interest in me.
I have no GM VSS anywhere on my conversion. This is likely the reason for the E38 stuck on 158 MPH. It is very possible a by-product is the fans will not work because of this. Sort of begs the question, what else in the tune is affected by vehicle speed? I really wanted the E38 to control my fans. If I can't get there, I guess I can always operate them on a grounding temperature switch. I still have one more rabbit hole, trying to get the Porsche ECM to control the fans, after all it used to and I transplanted the Porsche temp. sensor to the LS.
P.S. I flashed the E38 with the original junk yard tune and still got 158 MPH, automatic trans, and no fans.
An OS change like from auto trans to manual trans can only be done using other programming tools, like GM MDI/Tech2 and SPS. There are 8 segments in a Gen 4 ECM but HP Tuners only reads/writes 6 of them.
The OS determines a lot (or some) of the ECM's pin assignments. The auto trans OS is hard-programmed to get the VSS signal over CANbus, from the TCM (VSS is hardwired to TCM, check your wiring diagrams). But in a manual trans OS, the VSS is hardwired to the ECM because there is no TCM. You cannot transform an auto trans OS into a manual trans OS by changing the dumb little drop-down box to 'Manual'. I wish they would remove that setting from the editor entirely, because it does nothing except mislead people who don't know any better.
If you don't have GM programming tools and a SPS subscription, the quickest, easiest, cheapest way to get a manual trans OS is to buy a used ECM pre-programmed to a manual trans VIN. These are relatively cheap on ebay. Search for your service number and 'programmed to your VIN'.
BUT- if this is a swap vehicle, there's no compatibility issues with using a different year OS/ECM with better capabilities (and more common service numbers can be much cheaper than a one-year-only service number). A 2010-up ECM (12633238) with a 2010-up VIN from something that was factory built with a manual trans could be significantly cheaper, and get rid of some of the limitations of the early ECM.
Firstly, I will attempt to explain vehicle speed - as it relates to an E38 ECM, and the PID available in the HPT Scanner.
If an E38 ECM has been programmed with a calibration for use with an automatic transmission, then vehicle speed information originates with the TCM (T42 or T43) and is transmitted to the ECM over the CanBus network.
In your case, the base programming in the E38 ECM is for use with an automatic transmission. If the TCM is absent from the CanBus network, then the scanner will always show the maximum speed (default).
The scanner PID has a maximum value of 158 MPH. The E38 ECM allows for various maximum speeds, but most often this is 318 MPH to 512 MPH. If the vehicle is speed is 200 MPH, the scanner will display the speed as 158 MPH. If the vehicle is speed is 300 MPH, the scanner will display the speed as 158 MPH.
So, if the E38 ECM defaults to the maximum vehicle speed (512 MPH) due to a missing TCM, then the scanner will display a speed of 158 MPH.
In a Gen 4 (E38 or E67) conversion project, the "best practice" is to have a valid speed signal going to the ECM. This can come from a TCM, or from a pulsed input signal (if the ECM has been programmed using GM software with a manual transmission calibration).
Lastly, I am NOT stating that your fan issue is definitively due to lack of a valid speed signal, I am merely stating that it could be the case.
Last edited by Shrek; 10-30-2022 at 12:41 PM.
Reason: typo
Thank you so much. Tons of information that I got from nowhere else. I am a little scared to acquire and substitute another ECM for what I have. The one set of problems for another thing.
Here is my plan:
My E38 seems to want to run my slightly modified LS with VVT deleted without many problems.
My Porsche ECM has been altered slightly to make it's security and instruments and idiot lights work with the LS and the Porsche engine gone.
Both ECMs are wired so they can provide stage 1 and stage two fan relay grounds when or if they ever want to.
I am adding a temperature switch to ground in the coolant hose to the high-speed fan circuit.
In my mind this sort of kicks the can down the road, what do you think?
Correct. A 2008 L92 with LS3 intake and a mild cam. It is running. The E38 came with the engine and all I have done is remove VATS and disabled VVT. I also raised idle and air for the cam. The E38 has no VSS or transmission to look at. The manual transmission is Porsche. For the moment the Porsche ECU is not turning on fans, I do not know why. It may be looking for an engine run signal or who knows what. I can't get the E38 to turn on fans either. Can you help?
E38s ECMs controlled A/C 2 ways.
Trucks, Vans, Suburbans, Yukons, Tahoes..used the BCM
Camaro, CTS-V and Corvette didn't.
I had to swap to a camaro E38 to get it to read my a/c pressure.
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