RB26 Swap...final decision
07-18-2007, 11:42 AM
#42
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MP what I was saying was in reference to the stock ECU having ZERO control on the motor. Essentially what I'm proposing is:
Run a standalone EMS on the RB
Leave the VQ ECU in the car connected to the main harness
Create a board that will feed engine signals to the VQ ECU any time the car is on. These signals would replicate the output of a stock VQ at idle. Essentially what you would get is the stock VQ ECU sees idle reading on all of the channels it monitors including the O2 channels. The stock ECU ready state is achieved after a preset time frame of the stock ECU seeing input signals from the motor. So if you reset the ECU it will XX number of minutes before it shows ready. That number of minutes is how much time it has seen the engine input signals. So if you rig up a board to simulate all the engine sensor outputs from a stock VQ at idle and rest the ECU after that time has elapsed the ECU will see a ready state and it will think the stock VQ motor is on and at idle. If it sees this every time you start the car the stock ECU will simply assume the car is just at idle all the time. Meanwhile the RB motor is actually running and the stand alone is doing all the work of managing that with ZERO input/correlation to the stock VQ ECU. you basically have the stock VQ ECU in there just so that (a) you can pass an OBD2 scan (b) the stock functions from the BCM like power windows, AC, etc continue to function. The downside to this is that gauges and signals for the car will still be reading whatever the VQ ECU is outputting. Now for signals, brake lights, windows, AC control, etc that doesn't matter. What it does matter for is the gauges. Because your "board" is feeding the stock VQ ECU a replica of the engine signals of a motor at idle the gauges are always going to read as if you are at idle. Your tach will stay at idle, speedo at 0, etc. But this can be fixed as well. Replace all the factory gauges with Autometer stuff (speedo, tech, fuel level, coolant temp, oil pressure, voltage, etc) and wire them to the RB. You won't have factory gauges anymore but who cares. A full set of Autometer Nexus gauges can look and feel just like factory ones and will actually be more accurate. I haven't talked to KPierson personally but based on his understanding of factory ECU signals and his work on the VDC module and Brake Boost module this is something he is certainly capable of. All you need the board to do is send bone stock VQ35 engine at idle signals to all the engine channels on the stock ECU. Once you have that the ECU will always show ready and will never throw codes. The downside is you will lose things like VDC, ASM, stock gauges, etc but like I said who cares. These can be replaced or aren't needed anyways.
Run a standalone EMS on the RB
Leave the VQ ECU in the car connected to the main harness
Create a board that will feed engine signals to the VQ ECU any time the car is on. These signals would replicate the output of a stock VQ at idle. Essentially what you would get is the stock VQ ECU sees idle reading on all of the channels it monitors including the O2 channels. The stock ECU ready state is achieved after a preset time frame of the stock ECU seeing input signals from the motor. So if you reset the ECU it will XX number of minutes before it shows ready. That number of minutes is how much time it has seen the engine input signals. So if you rig up a board to simulate all the engine sensor outputs from a stock VQ at idle and rest the ECU after that time has elapsed the ECU will see a ready state and it will think the stock VQ motor is on and at idle. If it sees this every time you start the car the stock ECU will simply assume the car is just at idle all the time. Meanwhile the RB motor is actually running and the stand alone is doing all the work of managing that with ZERO input/correlation to the stock VQ ECU. you basically have the stock VQ ECU in there just so that (a) you can pass an OBD2 scan (b) the stock functions from the BCM like power windows, AC, etc continue to function. The downside to this is that gauges and signals for the car will still be reading whatever the VQ ECU is outputting. Now for signals, brake lights, windows, AC control, etc that doesn't matter. What it does matter for is the gauges. Because your "board" is feeding the stock VQ ECU a replica of the engine signals of a motor at idle the gauges are always going to read as if you are at idle. Your tach will stay at idle, speedo at 0, etc. But this can be fixed as well. Replace all the factory gauges with Autometer stuff (speedo, tech, fuel level, coolant temp, oil pressure, voltage, etc) and wire them to the RB. You won't have factory gauges anymore but who cares. A full set of Autometer Nexus gauges can look and feel just like factory ones and will actually be more accurate. I haven't talked to KPierson personally but based on his understanding of factory ECU signals and his work on the VDC module and Brake Boost module this is something he is certainly capable of. All you need the board to do is send bone stock VQ35 engine at idle signals to all the engine channels on the stock ECU. Once you have that the ECU will always show ready and will never throw codes. The downside is you will lose things like VDC, ASM, stock gauges, etc but like I said who cares. These can be replaced or aren't needed anyways.
07-18-2007, 12:53 PM
#43
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MIA, I understand what you are saying...but the ecu doesn't show a ready status after X number of minutes of seeing normal signals. It shows the ready status after drive cycles of stop and go traffic and constant speeds. The full operation if done in sequence takes about 20-25 minutes. There are 4 stages and each stage and each one handles specific ready codes. I used to have a printout of this, but can't seem to find it anymore. I drove a total of 150 miles before my car was "ready" to be inspected last month on a completely stock car...boy was I frustrated.
And GMan, I see what you are saying and it would be a good idea to call up GTM, but it is a little more complex than just flashing away codes for o2 sensors and emissions devices. You have to actually trick the ecu to think it is at a given rpm all the time, when there is no actual data being sent from the CAS at all. They might be able to do this though, I don't know, but it is very complex.
The only reason I have right now to not let it go is because the market is so awful for 350Z.
And GMan, I see what you are saying and it would be a good idea to call up GTM, but it is a little more complex than just flashing away codes for o2 sensors and emissions devices. You have to actually trick the ecu to think it is at a given rpm all the time, when there is no actual data being sent from the CAS at all. They might be able to do this though, I don't know, but it is very complex.
The only reason I have right now to not let it go is because the market is so awful for 350Z.
07-18-2007, 08:50 PM
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Originally Posted by 002-M-P
MIA, I understand what you are saying...but the ecu doesn't show a ready status after X number of minutes of seeing normal signals. It shows the ready status after drive cycles of stop and go traffic and constant speeds. The full operation if done in sequence takes about 20-25 minutes. There are 4 stages and each stage and each one handles specific ready codes. I used to have a printout of this, but can't seem to find it anymore. I drove a total of 150 miles before my car was "ready" to be inspected last month on a completely stock car...boy was I frustrated.
And GMan, I see what you are saying and it would be a good idea to call up GTM, but it is a little more complex than just flashing away codes for o2 sensors and emissions devices. You have to actually trick the ecu to think it is at a given rpm all the time, when there is no actual data being sent from the CAS at all. They might be able to do this though, I don't know, but it is very complex.
The only reason I have right now to not let it go is because the market is so awful for 350Z.
And GMan, I see what you are saying and it would be a good idea to call up GTM, but it is a little more complex than just flashing away codes for o2 sensors and emissions devices. You have to actually trick the ecu to think it is at a given rpm all the time, when there is no actual data being sent from the CAS at all. They might be able to do this though, I don't know, but it is very complex.
The only reason I have right now to not let it go is because the market is so awful for 350Z.
07-19-2007, 05:23 AM
#45
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Originally Posted by MIAPLAYA
Interesting. But doesn't the stock ECU only do this after a reset? Does the ECU go to non-ready state after long periods of downtime that don't involve a reset or in which the ECU keeps a 12 volt signal? I guess what I'm saying is that you could make sure the ECU gets to a ready state and then as long as you keep power to it throughout the swap process when you plug in the board to simulate the signals the ECU should have no reason to go back to non_ready state right? I guess I need to look into this a little more in the FSM. Of course the board could also oscilate its outputs across the acceptable ranges for the engine inputs on a time frame and it would do the same thing. Damn Nissan ECUs.
07-19-2007, 08:54 AM
#46
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Originally Posted by 002-M-P
Yea, it resets any time you tell it to through an obd-II scanner and/or anytime you leave the negative battery terminal unattached (aka alot if you are wiring two wiring harnesses together).
07-19-2007, 01:09 PM
#47
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Originally Posted by MIAPLAYA
Yeah I got that but what if the ECU keeps a 12 volt signal after its in ready state? It wouldn't reset then would it? I guess what I'm getting at is if you can put the ECU into ready start just before it goes in the final time with the board attached as long as it never got reset via OBD2 it would always show ready even if the only signal it ever gets is an idle signal right?
07-19-2007, 01:13 PM
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Originally Posted by 002-M-P
Yeah if it still gets a constant 12v after it is ready then it won't reset. But it is a pretty ballsy move to try and bank on keeping a 12v signal too it at all times during the swap and banking on it still being ready once the swap is complete. Isn't worth the risk. I would want to be fully confident that it will be ready before any proceedings.
The other alternative is having the ECU re-keyed to someone elses Z and having them use it while the swap is being done. The day you are ready to "go-live" you could swap it back to your car.
08-26-2007, 03:33 PM
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you need to call howard or tadashi at techno sqaure. they could help you through this aswell those two are so smart. i work at a shop and we do alot of work with them. i actually have an rb26 for sell. i almost did the same thing. but have got alot more serious into racing my dirtbike and need a truck now. so by by z. new tundra it is. give them a call theyll for sure be able to point you in the right direction and help you out.
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