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Hello, we have developed a special fuel system for a GM L8T out of a 2022 2500 HD. We would like to use the 2022 2500 HD for our demonstration vehicle. This vehicle will only be used for off road use. We do have some experience with some older GM ECM's and HP tuners but not this newer E93 and T93. We would like to be able to put this fuel system into the vehicle and parallel the factory system. We are planning to split the crank, cam, and APS signals to our other ECM. We were planning on using any sensor that factory ECM needs that will allow most other functions in the truck to work properly. We really just want the dash to work and be able to tune the TCM and it function properly. Our engine will have a different torque curve. We plan to use a different throttle body but still hook up factory throttle body so the initial calibration takes place. We are going to try and use an analog to SENT converter to send the TPS signal to the E39 ECM. We really do not want to hook up the injectors or the coils but we can if we have to. Can we turn the DTC off for the injectors, coils, and other sensor and everything still work in the truck. We just want to be able to drive the truck and it shift good. Do you see any issues with us being able to make this happen?
Sorry I'm a little confused about what you're trying to achieve here? Are you aiming to run a port injected fuel system on this L8T? The reality is I can't give you a definitive answer as to whether what you're wanting to attempt will work as you expect. In theory as long as you're providing all the required signals to each ECU this 'should' be possible, however there are several potential stumbling blocks when trying to share these signals - For example you're not going to be able to easily share the likes of an ECT or IAT signal as both of these rely on the pull up to 5V inside the ECU to convert their variable resistance into a voltage. As soon as you try and share that signal to the second ECU you're going to introduce a second 5V pull up which will skew the measured value. I haven't looked into analog to SENT conversion but you're going to need some very fine control over the resultant TPS voltages to make this work without ending up with a bunch of DTCs. I don't have a calibration that I can look at for the L8T to confirm what control over DTC's HPT provide but you can easily have a look for yourself. I'd suspect that you probably can turn the relevant DTCs off though.
Hello, with our current design we are port injected using NH3. We are using a Bosch MS6 and PBX units. We do understand about the pullups and making sure the signals are correct. Another way to ask the question would be, if there is a DTC that you can select, "No Error reported", will this actually make the rest of truck functionality work? Our main goal is to make the truck go into gear, AC work, and dash function. The one thing I don't know how to get around would be if the coils and injectors are not hooked up will this cause it to go into limp mode where it will not let the transmission go out of 1st gear? I can not remember because it's been a while but let's say you didn't want the oil pressure sensor in the system. Would just turning off the DTC to "No Error reported" cause the ECM to function correctly and not go into limp mode? Any insight is helpful. We need to decide on a demonstration vehicle and we would like to use a vehicle of the modern age.
It sounds like you're trying to do what a lot of Corvette guys do when they switch to a standalone, and still want the factory instrument cluster to work. So, they use the factory ECM to run the instruments, AC etc (because it's connected to the factory CAN), and have the other ECM/TCM run the actual vehicle.
If that's the case, I believe you can set all of the DTCs to "No Error Reported" and you have to make sure the Crank sensor is sharing the signal between both ECMs. As far as "limp mode", I can't say if you'd trigger it on the factory ECM, but if you're not connected to the engine directly, it shouldn't matter since the engine control is being done on the other ECM, and the factory ECM becomes a glorified CAN interface.
I haven't done this myself (my car didn't use the factory cluster, so I didn't need to do this), but I could probably download a file from my friend's factory ECM to see how they have it setup to run the instruments without running the engine. He's running an E38 ECM, but the idea should be the same.
Ken, thank you for the information. My experience is with the E38 with a manual Transmission but I never tried to not run the coils and injectors or biggy pack on the factory dash. We want to be able to change the torque map and shift points to make it drive better if we need to. I was just hoping to confirm that the E90/E93 can do this without putting it in some kind of limp mode where it will not shift properly.