Standalone ECU for stroker

[geeknahalf]

Hey folks,
Anybody have real world experience with standalone ecu for jeep 4.6 Strokers w/42RLE transmissions? I’m thinking there is a better solution out there than the factory ECU, that will afford us better drivability and more power. I am interested in any input that is gained from experience.
Thanks in advance!

[mpgMike]

I'm using www.rusEFI.com UAEFI on my '95 ZJ 4.6 stroker. It's like a modern MegaSquirt: open source, low price (I paid around $200 US for mine), uses Tuner Studio... Whereas the old MegaSquirt could handle the basics, the UAEFI has a built-in WB O2 controller, DBW capable, VVT controls, and a host of configurations for boost, nitrous, etc. I added a knock sensor, and it plugs right in to a dedicated Knock pin. Have a look.

rusEFI1.png

[geeknahalf]

Much appreciate it!

I looked into it, and it says it does not support OBD II. Since it’s a standalone ECU, does that matter? And if it doesn’t, why do they state that?

Forgive any questions that may seem ignorant, I am very much ignorance in this subject.

Sorry, to clarify, it is the EFI analytics that does not support OBD II. Which is where the tuner studio is download it from I believe

[mpgMike]

That simply states you cannot plug a J1962 connector in and communicate with any of the 11 standard OBD II protocols, that it does not generate standard DTCs, etc. If you use it as I am, as a Daughter Board, OBD I or OBD II doesn't matter. You WILL get a check engine light on your factory PCM, but you will have full authority over fuel, spark, and anything else you wish to control. The factory PCM can keep the tachometer spinning, AC and cruise working, etc.

[geeknahalf]

Ok, thx for the info. I contacted them to see what their recommendations are to completely replace the factory unit while retaining my dash gauges, ac, etc. Or replace dash as well.

How did you use yours a daughter board, and did you have to run wires to the sensors?

[mpgMike]

I spliced into CPS, CMS, NB O2, TPS, MAP, but had to modify the rusEFI board (desolder resistors) to tap into CTS & IAT. I ran a separate wire for the ignition coil. I carry a Phillips & 3/8" wrench in case I have to swap ignition coil back to stock. I added Amphenol connectors for other stuff so I could easily swap back to stock if I ran into issues. The factory PCM still controls tach, AC, cruise (verified still works), and other stuff. I have several threads going. Take a look at:
viewtopic.php?t=6790

https://rusefi.com/forum/viewtopic.php? ... fc9#p50464

https://www.jeepforum.com/threads/time- ... n.4480984/

[geeknahalf]

Awesome, thanks for the info and links. Checking them out.

[geeknahalf]

OK, so I looked over the links…
That’s one hell of a project you have going on, excellent job! You have a lab, that’s awesome!!

Based on what I saw in your forum posts you have an in depth understanding regarding the electricals of an engine, and how they work.

I hope you’ll be willing to assist me in resolving my issue.

I connected a body ground to my engine, and got a low voltage code for the bank 1 sensor 1 (B1S1) O2 sensor. After about 15 minutes of idling the engine shut off and wouldn’t start. I removed the body ground, reset the adaptive memory, and the engine started / ran as normal.

Any ideas on what would cause this? Clearly I have some electrical issues going on, that may be contributing factors to the engine issues i’m experiencing.

Much appreciate your help

[mpgMike]

Not sure what you're asking. You connected a body ground to the engine -- from where? rusEFI or factory PCM? You got O2 sensor codes, presumably on your stock PCM, right? Please elaborate a bit.

[geeknahalf]

Sorry sometimes I don’t speak too clearly.

I’m running a stock cpu, and when I connect the ground from the firewall to the engine, that’s when the aforementioned issues happen. I’m beyond lousy at troubleshooting electrical issues, and was hoping you might be able to give some insight on what to check. Not much more info I can give.

Thx

[mpgMike]

Ideally your battery negative, engine block, body, and all PCM grounds should be at the same voltage potential. Through rust and corrosion, resistance builds up in ground connections, and even the wires themselves. I suggest disconnect all of your grounds, inspect and clean the terminals, making sure you have 0-1 ohms resistance to battery negative max. Look for the actual wires turning green. That happens often. It can work up into the wire, under the insulation, and cause high resistance.

Your oxygen sensor has a signal return (ground) wire built in. Disconnect the sensor (with engine & key OFF) and measure resistance between that wire and battery negative. The connector is by your power steering pump. Sensor ground will be a black wire with light blue tracer.

[geeknahalf]

Appreciate the response, however, I think my issue lies in the wiring harness. While the engine was running I jiggled the harness and it shut off.

Looking at the harness closer, it seems the previous owner did some splicing and dicing with it. I think I’m gonna look for a different one.

[geeknahalf]

To elaborate, I moderately twisted the firewall wiring harness above the valve cover and the engine shut off.

[mpgMike]

The cross-over behind the cylinder head is a common place for chafing, charing, and other issues. At least you have a clue now. Maybe swing it over the head where you can see and work with it. Pull back the convolute tubing and start pealing away the tape. Failures aren't always blatantly obvious. You may have to make sure the wires separate without pulling apart. Melted insulation can get 2 wires in close proximity, sufficient that they occasionally touch. Best of luck.