GM Programmable ECM or Stock ECM for 4.7 Stroker? - JeepForum.com
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post #1 of 10 Old 06-02-2021, 05:11 PM Thread Starter
Vernors
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GM Programmable ECM or Stock ECM for 4.7 Stroker?

Hi,

Just completed 4.7 stroker with following parts:

HESCO MPFI, 1994 ECU
7120 Head, port matched to exhaust and intake
2000+ Intake
Roll Master Timing Chain
4.2 Crank
4.0 connecting rods
4.0 Renix Block
Keith Black KB424 +0.060" bore pistons
Bishop Buehl Racing/ CompCams 68-235-4
Bishop Buehl Racing valve springs
Victor Reins.043" head gasket
0 deck quench
Meling High Flow Oil Pump
Ford Cobra 24 lb injectors
Holley Adjustable Pressure Fuel Regulator
62 mm Throttle body

jCC'd the head and it's 57.6 cc's.

Static Compression: 9.26/1
Dynamic Compression: 7.8/1
Intake valve closing angle: 58

Considering going with GM ECM (#1227727) and using TunerPro to make adjustments.....although, I don't know if its worth it vs staying with stock ECM and adding adjustable MAP.

The engine runs pretty smooth and starts well, but I wonder if I'm leaving power on the table without specific tuning. I'm not going to add supercharger or turbo.

Thoughts?

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post #2 of 10 Old 06-04-2021, 12:00 PM
cobra30689
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My knowledge of the 7727 PCM is limited at best (although I have used TunerPro on my LS1 Camaro). But now you have me wondering if it's possible to go one step further, and upgrade to an 0411 PCM and have the benefits of sequential EFI (and tuning ease with HP Tuners rather than burning PROMS). The 4.3 Silverado calibration uses a distributor with integral cam sensor, so *maybe* this could be retrofitted to a Jeep dizzy (or HEI)? Not sure how you would handle the 3x crank trigger signal though. Maybe try the gearhead-efi forums?
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post #3 of 10 Old 06-06-2021, 06:40 AM
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The factory jeep ECM is sequential MPFI, it uses a camshaft and crankshaft position sensors. Each injector only fires when that cylinders intake valve is open.
The 1227727 GM ECM is port fire/batch fire. Meaning it fires all the injectors at the same time. While that system works fine (hundreds of thousands of vehicles out there using a system like it), it is a outdated system, not as ideal, and would be a step backwards in technology compared to what you have now. However there is the upside that it can be tuned pretty easy with tunerpro and has some aftermarket support, where the Jeep ECU can not be tuned.
To use the 7727 you will not be able to use the jeep crank sensor or the jeep cam sensor. You will not even be able to use the jeep fuel injection distributor, as it is set up for a 1x cam sensor. To use the 7727, you will need a 6x magnetic pickup. Basically you will need the distributor from a older carb 258. You will then need to lock out the mechanical advance and the vac advance. Lots of info out there on how to do that. A good place to start is gearhead efi forums.

I have built and tuned a batch fire system for the 401 in my old 79 cherokee and that place was a big help. The system in it is based off a 16197427, as I started out with TBI, but then just modded it to run 8 batch fire injectors instead of swapping to a completely different ecm and starting the tuning process over again.
I actually had plans to do the exact same thing as you and swap the ecm in my 93 YJ for the 7727 so I could tune it. In the end I decided not to and decided if I was to swap to a tuneable ecm, I would swap to the 12200411 so I could keep the sequential injection. However life has gotten in the way and I have not been able to take on that project yet.
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'93 YJ 4.6L stroker, AX-15, NP-231HD/SYE, 8.8in rear, OME 2.5 lift, home made front hub conversion, hydroboost. Warn M10000 winch.

'79 Cherokee Chief, 401 MPFI fuel injection, T-18/D-20 and hydroboost. Otherwise stock.
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post #4 of 10 Old 06-06-2021, 02:46 PM Thread Starter
Vernors
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Ahhh, interesting. I didn't realize that various parts would need to be changed in order to run the 7727.

One problem I'd encounter with the 12200411 is that my ECU is in the engine bay and this one appears to be an in-cabin only ECM. I assume a wiring extension could be used. Is there a waterproof version or an alternative that can also be used with the 4.0?

A challenge with the 7727 is that the chipset either needs to be pulled and programmed outside of the ECM or an emulator would be needed to plug into the ECM where the current chip goes, and the chip plugged into a burner linked to the emulator. The benefit is being able to drive the jeep between code changes without having to unplug everything for each tweak. Is the 12200411 the same format?
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post #5 of 10 Old 06-06-2021, 04:30 PM
cobra30689
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Quote:
Originally Posted by Vernors View Post

One problem I'd encounter with the 12200411 is that my ECU is in the engine bay and this one appears to be an in-cabin only ECM.
The 0411 is fully weatherproof. I have 2....my Z28 is mounted under the hood from the factory, and my Jeep will be mounted on the fender. The 7727 would have to be mounted in-cabin.

Quote:
Originally Posted by Vernors View Post

A challenge with the 7727 is that the chipset either needs to be pulled and programmed outside of the ECM or an emulator would be needed to plug into the ECM where the current chip goes, and the chip plugged into a burner linked to the emulator. The benefit is being able to drive the jeep between code changes without having to unplug everything for each tweak. Is the 12200411 the same format?
No, the 0411 can be tuned and flashed with software. Either HP Tuners, or TunerPro with something like PCM Hammer and a J2534 device (I have a MDI clone that I have successfully used....if only to delete VATS to get the Jeep running).
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post #6 of 10 Old 06-13-2021, 06:23 AM
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The 12200411 is a weatherproof underhood mounted ecm. It is a OBD2 ecm and has to be reflashed via the diagnostic port.
The 1227727 is also a underhood weatherproof ecm. It is a OBD1 ecm and is reprogrammed by removing a cover plate and removing the chip to reflash the chip using something like a autoprom from moates. (you will also have to swap out the factory chip to one that can be reprogrammed)

You guys might also be confusing the 1227727 ecm with the 1227730 ecm. The 1227730 is a non weatherproof ecm that is mounted under the dash.
The 1227727 and the 1227730 are electronically the same ecm. Just the 7727 is waterproof and the 7730 is not.

'93 YJ 4.6L stroker, AX-15, NP-231HD/SYE, 8.8in rear, OME 2.5 lift, home made front hub conversion, hydroboost. Warn M10000 winch.

'79 Cherokee Chief, 401 MPFI fuel injection, T-18/D-20 and hydroboost. Otherwise stock.
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post #7 of 10 Old 06-13-2021, 06:27 AM
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I think for a 4.0L that's stroked the factory engine controller should be able to adapt within a few miles and get you back to optimal air-fuel mixture

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post #8 of 10 Old 06-14-2021, 05:01 PM Thread Starter
Vernors
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I've heard the same, Pinecat. The factory ECM does a pretty good job, but would like to dial in performance for both power and drivability.

Thanks for the suggestions Cobra, I'm leaning more towards a JTEC system but will look into the 12200411 to see how complicated it would be to swap in. I don't know if it requires sensor upgrades, etc. But, on the flip side these ECM's are only $50 on eBay....which I definitely like : )
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post #9 of 10 Old 06-20-2021, 07:30 AM
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I am still using my factory ECM in my 93 YJ with my stroker and it works fine. I upgraded the injectors when I stroked the engine.
As long as the injectors are sized right, the factory ECM can adjust the fuel map up or down a set amount. Every "closed loop" fuel injection system does this. That is how it adjusts the fuel for changes in elevation, barometric pressure, and temperature changes.
The problem is there is no internal tuning you can do. You can not change the timing map, adjust acceleration enrichment and power enrichment, and may other parameters you would like to change when you actually can.
There are a few people who have hacked and tuned the factory jeep ECM's, but there is no widespread support for it. The OBD1 ECM's (91-95 YJ's use them) are called the SBEC (single board engine controller). To even be able to tune them, you would have to dig out the potting and unsolder the chip and then installed something like a DIP socket that allows the easy install and remove that eeprom and then erase and reprogram it. You would then need some way to read and change the factory bin files, and something to use to reprogram the chip (a autoprom might work, with the correct software)

The OBD2 ECM's are called the JTEC (jeep truck engine controller). I did a little looking this morning and it would appear as though HP tuners is now offering support for the JTEC's. Last time I looked into years ago there was pretty much no support for it yet, just like the SBEC. But it looks like the started offering support a couple years ago.
https://forum.hptuners.com/showthrea...g-JTEC-Support!

The GM 12200411 ECM, the basic jeeps sensors will work. The TPS, MAP, IAC (with the proper wiring). The crank sensor will not have the correct number of teeth on the flywheel for the correct pulses. So a new crank trigger wheel would have to be made and mounted on the front of the engine on the harmonic balancer and a pickup mounted there as well. The cam sensor should work. The temperature sensors (IAT and coolant) would have to be changed to the GM sensors. Injectors will work, as well as the coil.
The crank wheel and pickup would be the most difficult part. There will also be a good bit of tuning because the GM engine are a good bit different than the Jeep engines, so the tune will be off a good bit.

Now that I know that HP tuners offers support for the JTEC, I would think that would probably be the best way to go. That way the ECM would be more or less plug and play. All you would need to do is cut off the original SBEC connector and splice in the JTEC connectors and then you should be able to crank it up and go. You would still be using all the factory jeep sensors. As far as I know, they will all work with no issues. Just find a JTEC from a 97-01 TJ with a 5 speed.
I may be looking into this a little more myself.

'93 YJ 4.6L stroker, AX-15, NP-231HD/SYE, 8.8in rear, OME 2.5 lift, home made front hub conversion, hydroboost. Warn M10000 winch.

'79 Cherokee Chief, 401 MPFI fuel injection, T-18/D-20 and hydroboost. Otherwise stock.
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post #10 of 10 Old 06-21-2021, 01:49 AM
WestfieldMX5
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You could look into getting a Megasquirt.


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