E40 vs alternate 24X ECMs (Page 1/2)
Daviero JAN 24, 10:58 PM
The E40 ECM was the last ECM for the 24X LS, and has does not seem to have universal good reviews. A comparison of the E40 to other 24X ECM's does not seem to have been made on the forum, at least by a search of thread subjects, so her it is.

For full disclosure, I am also trying to decide which ECM to use for my own LS4 swap. I already have an E40 and harness from a 2006 Grand Prix but am having reservations on using it. I am replacing a Northstar that ran on an OBD1-7765 ecm using a RAM chip adaptor and custom Bin for several years and never got to 100% satisfaction with it. I want to avoid this same experience with whatever ecm I use for the LS4, hence this thread. Others can also likey benefit from the same information.

This article and another Youtube are the most informative info I found about the ECM’s but neither helps in basic decision about which to use for a swap and why. What's available or what you already have is not a good enough single reason.
Article: The Tuning School Differences and Applications of GM ECMs
Video: PSI How To: Which PCM should I use on my LS / LT Swap


E40 ECM:
- used in 2005/6 in relatively few vehicles including Grand Prix, Impala, Rainier, SSR, Trailblazer, Envoy, GTO and Corvette
- many posts and writeups refer to the E40 as peculiar and somewhat un-intuitive
- the E40 was still airflow/VE based, and a Gen3 ecm but was a trial ECM for the next Gen4 ecms to come. One write up I read compared it to being like OBD1.5 when we transitioned from OBD1 to OBD2.
- not all pinouts seem to be the same, I have compared the Vette and Trailblazer pinouts to my Grand Prix harness and neither pinout matches completely.
- very few details about the E40 ecm seem to be public either on internet or in print, especially all pinouts and wiring diagrams, except perhaps subscribing to AllData or similar databases. (A single vehicle short term registration with a database is cheap and not a deal breaker, as long as one knows which vehicle to use as the reference)
- Cruse control is not through the ECM but rather the TCM, so even a manual car must retain the TCM
- not sure about how A/C interfaces with the E40
- a benefit of the E40 is that it is relatively small, and the TCM is even smaller so its not a big deal to still have to keep it.
- the fuel delivery is maxed at 64 lbs per hour, not likely a concern for an average LS4
-flex fuel capable if enabled in the tune? Not sure.

Alternate (older) ECM's
P59 (Blue/green plugs, 2003 to 2007)
-used in a lot more vehicles and plentiful to get
- bigger package, so not so easy to hide away
- engine and trans control in one and mostly DBW
- plentiful amount of pinout, wiring, and tuning support available including a/c, cruise, and flex fuel
- fuel capacity is 254 lbs per hour, not likely a requirement for the average LS4

P01 ( blue/green plugs, 1999-2002)
-used in a lot of vehicles and plentiful to get
- same size as P59
- engine and trans control in one and mostly DBC
- plentiful amount of pinout, wiring, and tuning support available including a/c, cruise

So what ECM to use to use? The P59 seems to be more straight forward to integrate DBW, cruise, A/C and Flex fuel despite it being a larger unit. Is it worth the bother to find all the required info for the E40? Does the E40 do anything that the P59 doesn’t other than take up less space?

Please offer your informed opinions.

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Daviero - 88 N* 5spdGT

fieroguru JAN 25, 07:14 AM
I am using the E40 with my LS4/F40/Turbo swap.

Sure the E40 is the stepchild of the LS ECM family but so is the LS4... and that clearly didn't stop us.

I am using the 2006 SSR LS2/T56 base calibration. This one has cruise and VSS direct wired to the ECM. With the pressure sensor feedback, A/C won't need a discrete input to function and idle. It also is the factory ECM for use with the 90mm LS2 throttle body. I switched my engine from 58X so 24X to get the real VE table vs. the virtual one, for the integrated cruise.

For my application, I will be running the 2 bar OS (just selected in the calibration), and scaling the tune to be about 75% vs. 100%. This will allow me to get past most of the hardcoded limits for injector flow rate and MAF flow rate while still reaching my power goals. I also plan to run flex fuel enabled.

Look at enough pinouts from different applications of the same ECM, you will see wiring differences... the key is to buy the factory service manual for the calibration you plan to run and forget all others (unless you are looking for a specific input/output that isn't present on your OS (like VSS output), then ooking at other applications with the same ECM can show you a pin that "might" work).

The E40 is a little more unique than some of the other ecms, but it still can work well, especially for close to stock applications. It has also been used on several 800+ hp turbo cars, so it is capable.
I think people run into issues by blindly copying and pasting values from other calibrations into the tune w/o paying attention to the X & Y units.

The other 24X ecms work as well, but some will need a TAC module to control the DBW throttle body, and some have issues running the 90 mm throttle bodies. So no matter which ECM you choose, you need to learn the details of what works, what doesn't and plan accordingly.
Daviero JAN 25, 11:06 AM

quote
I am using the E40 with my LS4/F40/Turbo swap.


Thanks for chiming in, I'd hoped you would as I've read your pages, some multiple times. We all see farther standing on the shoulders of Giants.

Hoping you can clarify a few points:
The VSS output is no big deal. I didn't have one on the previous 7165/Northstar setup either so I use a GPS based signal generator for the speedo signal. Works good, except in long tunnels or overpasses.
You intend to use a 2 bar setup and "fool" the hard setpoint max fuel rate by factoring the actual VE to an apparent VE for a given injector duty? What injectors do you use?
When using the SSR/T566 calibration, one must revise any differences in the pinout of the harness being used (in my case the Grand Prix) to match the SSR pinout? Essentially creating an SSR/T56 harness. This seems like such an elementary point that I think is "yes" but is one I am stuck on.
Given your details, the E40 should work fine as my LS4 is pretty much stock (LS6 like non DOD cam, 90mm intake, LS6 exhaust manifolds, 10 thou overbore). If in the end, having no VSS output is the only real deficiency perhaps its the right choice to use.
I do like the size of it since its easier to squirrel away.

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Daviero - 88 N* 5spdGT

Daviero JAN 25, 11:09 AM
I'm reminded that I'll soon have to change my signature to 88GT/LS4/F40 since the Northstar/5spd is gone to another member.

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Daviero - 88 N* 5spdGT

fieroguru JAN 25, 06:51 PM

quote
Originally posted by Daviero:

Thanks for chiming in, I'd hoped you would as I've read your pages, some multiple times. We all see farther standing on the shoulders of Giants.

Hoping you can clarify a few points:
The VSS output is no big deal. I didn't have one on the previous 7165/Northstar setup either so I use a GPS based signal generator for the speedo signal. Works good, except in long tunnels or overpasses.
You intend to use a 2 bar setup and "fool" the hard setpoint max fuel rate by factoring the actual VE to an apparent VE for a given injector duty? What injectors do you use?
When using the SSR/T566 calibration, one must revise any differences in the pinout of the harness being used (in my case the Grand Prix) to match the SSR pinout? Essentially creating an SSR/T56 harness. This seems like such an elementary point that I think is "yes" but is one I am stuck on.
Given your details, the E40 should work fine as my LS4 is pretty much stock (LS6 like non DOD cam, 90mm intake, LS6 exhaust manifolds, 10 thou overbore). If in the end, having no VSS output is the only real deficiency perhaps its the right choice to use.
I do like the size of it since its easier to squirrel away.




The E40 has a VSS output (CI Pin 21), so no need for a GPS based speedo.
The use of the 2 BAR OS is just to allow the ecm to read boost pressure, it doesn't address any hard limit issues.
The scaling of the calibration is to get past the hard coded flow limits. Basically you tell the calibration the engine is a 75% of 5.3L = 3.975L and adjust all air/fuel tables the same %. The ecm will think it is controlling a 4.0L engine and all the calculated values for air flow and fuel use will be less, so you can create more actual power before reaching the hard coded limits. Here is some more info:
http://injectordynamics.com...13/12/SteckScale.pdf

When I do my swaps, I de-pin everything into the individual circuits, then build the harness back 1 sensor/device at a time, routing it the way I want it, and then terminating the wires at the ecm connectors based on the ECM pinout for the calibration used - for my swap I am started with a GTO/T56 harness and building it back as a SSR/T56 harness.
Daviero JAN 26, 12:23 AM

quote
When I do my swaps, I de-pin everything into the individual circuits, then build the harness back 1 sensor/device at a time, routing it the way I want it, and then terminating the wires at the ecm connectors based on the ECM pinout for the calibration used - for my swap I am started with a GTO/T56 harness and building it back as a SSR/T56 harness.



This all makes clear and obvious sense now - thanks for making it so.
Darth Fiero FEB 01, 02:40 PM
Honestly, I would avoid using the E40 ECM if you have a choice. The reason why is because of the scarcity of these units and also the price. A number of vendors on ebay and Amazon started listing bead-blasted used E40's for $700 just a few years ago and that drove the price up everywhere. The E40 was only used for 2 model years and in very few vehicles; GM also discontinued making new ones a number of years ago. All that's available now are junkyard pulls. So finding a replacement isn't going to be as simple as strolling into your local auto parts store; nor will it be cheap.

To add insult to injury, GM mounted them on the frame rail in the TrailBlazer/Envoy SUV's which exposed them to mud and road dirt. If you are not extremely careful unplugging them, it is very easy to snap off the locking tabs on the E40's electrical plugs. I've got a number of E40's sitting here with all the locking tabs snapped off at least one of their plugs so the only way to keep the harness-side connector engaged with the ECM is to put some zip ties or a big hose clamp around it. These ECMs do go bad (internally) as well. I've a couple sitting on the shelf that are dead.

So what can you use besides an E40? Well, you have a couple of options and it also depends on what transmission you are going to be using.

If you aren't opposed to disassembling the engine, you could install a 4x cam / 58x crank sensor which would then allow you to use a newer E38 or E67 ECM (which are far more common).

If you are using a 4T65-E trans, then you're going to need a TCM to control that - factory or aftermarket. The E40/T42 combo was used in 2005-06 FWD LS4 (24x)/4T65-E applications and the E67/T42 combo was used in the later LS4 (58x) cars.

You can use a P01 (blue/red) 24x PCM (cable-op TB), but it probably can't be made to control a 4T65-E trans (but it will work with a manaul).

Of course you could use a P59 (blue/green) 24x PCM (DBW TB), but it also probably can't be made to control a 4T65-E trans (but it will work with a manaul) and it will require an external TAC (throttle control) module which may not be compatible with an OE LS4 DBW TB.

-ryan

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More is more. Less is not enough.

Custom GM OBD1 & OBD2 Tuning | Engine Conversions & more | www.gmtuners.com

ericjon262 FEB 02, 03:05 PM

quote
Originally posted by Darth Fiero:

You can use a P01 (blue/red) 24x PCM (cable-op TB), but it probably can't be made to control a 4T65-E trans (but it will work with a manaul).






The P04 can control a 4L60e, or a 4T65e, I don't see why the PO1 wouldn't be able to, the pinouts for the 4L60e and 4t65e P04 are almost identical, with the 4T65e using an input shaft speed sensor, and the 4L60 not. I'm sure it would take quite a bit of tuning though.

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"I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."

I invited Lou Dias to trash me in my own thread, he refused. sorry. if he trashes your thread going after me. I tried.

RacerX11 FEB 02, 07:50 PM

quote
Originally posted by Darth Fiero:

Of course you could use a P59 (blue/green) 24x PCM (DBW TB), but it also probably can't be made to control a 4T65-E trans (but it will work with a manaul) and it will require an external TAC (throttle control) module which may not be compatible with an OE LS4 DBW TB.

-ryan



I have experience using a P59 with TAC to control an OE LS4 DBW TB. Once wired correctly to account for the throttle position circuit differences, it works fine.

Marty
Darth Fiero FEB 03, 03:20 PM

quote
Originally posted by ericjon262:
The P04 can control a 4L60e, or a 4T65e, I don't see why the PO1 wouldn't be able to, the pinouts for the 4L60e and 4t65e P04 are almost identical, with the 4T65e using an input shaft speed sensor, and the 4L60 not. I'm sure it would take quite a bit of tuning though.




I haven't personally tried to wire up a 4T65-E under P01 or P59 control, so I didn't want to say it would work, for sure. I do think it might be possible to make it work.

[This message has been edited by Darth Fiero (edited 02-03-2023).]