The_Magicians_Eye Posted July 17, 2011 Share Posted July 17, 2011 Will an ECU out of a 95 Pathy with an auto trans (2 wheel drive) work in my 91 with an auto trans (4x4)? I'm looking to get an extra ECU to have sent into have it reprogrammed so I don't have any down time. Link to comment Share on other sites More sharing options...
Kingman Posted July 17, 2011 Share Posted July 17, 2011 Yes. Link to comment Share on other sites More sharing options...
The_Magicians_Eye Posted July 17, 2011 Author Share Posted July 17, 2011 Yes. Good deal. I bought it taking a risk. I'm going to install it just to see it it makes any difference at all in the way my truck runs. My fuel mileage is complete crap compared to some of the numbers you guys claim to get so I'm curious of this other ECU will make any difference at all. I'll more than likely send the stock on in to get reprogrammed. I plan on getting new cams too so I'll have it programmed for them and the exhaust. Hopefully it will be worth every penny. Link to comment Share on other sites More sharing options...
The_Magicians_Eye Posted July 18, 2011 Author Share Posted July 18, 2011 Ok so let me add to this "yes" answer. Yes it will work but make sure you aren't putting a Cali ECU into a non Cali truck like I did. It's pulling a 35 on the computer cause I don't have that part in my truck!!!! Ok so now my next question is what do I need to look for in the vin to find out if the truck is a California truck? Link to comment Share on other sites More sharing options...
The_Magicians_Eye Posted July 18, 2011 Author Share Posted July 18, 2011 good thing I tested it before sending it off to be reprogrammed! That would have been a really costly mistake. Link to comment Share on other sites More sharing options...
The_Magicians_Eye Posted July 18, 2011 Author Share Posted July 18, 2011 One more question. does the ECU effect how your auto trans shifts? When I put the Cal ECU in I noticed a difference in the way my trans shifted. It felt better. Now that I put my old one back in it's back to it's abnormal shift points. Am I high or could it have made a difference? Link to comment Share on other sites More sharing options...
Cuong Nguyen Posted July 18, 2011 Share Posted July 18, 2011 (edited) The transmission has it's own computer--- TCU. It's located in the rear right quarter panel in cargo area just above the wheel hump. It does the shifting I think. I converted my 2 wheel drive to 4 wheel drive and I'm still using the 2wd ecu with no problem. I cannot comment on it affecting shift points though. Edited July 18, 2011 by Cuong Nguyen Link to comment Share on other sites More sharing options...
Tungsten Posted July 18, 2011 Share Posted July 18, 2011 (edited) The 95 ECU is different from a 91 because it incorporates a "Vehicle Speed Sensor" and it uses a different oxygen sensor on top of that. The way you can tell if it's a California model is to look if the EGR system has a temperature probe for EGR monitoring because all California models have a monitored EGR system. Edited July 23, 2011 by Tungsten Link to comment Share on other sites More sharing options...
The_Magicians_Eye Posted July 19, 2011 Author Share Posted July 19, 2011 So what years can I pull an ECU out of to work in my 91? I'm taking the one I have back to the yard this weekend and I hope to find one that'll work. Link to comment Share on other sites More sharing options...
Tungsten Posted July 19, 2011 Share Posted July 19, 2011 (edited) Anything with a mechanical speedometer, an MPFI setup, and the small 12mm O2 sensor. I'm thinking anything between 1990 and 1995 and not the California models. Edited July 23, 2011 by Tungsten Link to comment Share on other sites More sharing options...
The_Magicians_Eye Posted July 20, 2011 Author Share Posted July 20, 2011 Since I'm hunting in the wrecking yard for an ECU most the trucks are without an engine and have everything pulled from the dash. How can I tell if it's a Cali truck based on the vin? Also what years did they start putting in the round dashes. Everything they had in the yard when I went had the round dash style. Not the square one like my 91 has. Link to comment Share on other sites More sharing options...
Tungsten Posted July 20, 2011 Share Posted July 20, 2011 (edited) I think you may be able to get away with a late model ECU but you will probably need a different O2 sensor. Not sure as to how the ECU will respond to no VSS. Make sure there is no monitoring set-up on the EGR. Edited July 23, 2011 by Tungsten Link to comment Share on other sites More sharing options...
The_Magicians_Eye Posted July 20, 2011 Author Share Posted July 20, 2011 Not sure as to how the ECU will respond to no VSS. Ok sorry is this is a stupid question but what does VSS stand for? Link to comment Share on other sites More sharing options...
Tungsten Posted July 20, 2011 Share Posted July 20, 2011 Vehicle Speed Sensor, the round dashes have electric speedometers Link to comment Share on other sites More sharing options...
The_Magicians_Eye Posted July 20, 2011 Author Share Posted July 20, 2011 Vehicle Speed Sensor, the round dashes have electric speedometers Oh ok. Thanks for all the help. I'll be headed back to the wrecking yard this weekend and hopefully they will have one that works for me. Link to comment Share on other sites More sharing options...
JamesRich Posted July 20, 2011 Share Posted July 20, 2011 Vehicle Speed Sensor, the round dashes have electric speedometers Even my 87 has a VSS, it is on the back of the speedometer. The round dash started in 94. I think the harness for the ecu will be different than you 91. James Link to comment Share on other sites More sharing options...
adamzan Posted July 20, 2011 Share Posted July 20, 2011 Even my 87 has a VSS, it is on the back of the speedometer. The round dash started in 94. I think the harness for the ecu will be different than you 91. James Exactly, how do you think the cruise would work without a vss Link to comment Share on other sites More sharing options...
The_Magicians_Eye Posted July 20, 2011 Author Share Posted July 20, 2011 Even my 87 has a VSS, it is on the back of the speedometer. The round dash started in 94. I think the harness for the ecu will be different than you 91. James The harness is the same. I have a newer one that plugged right in. Link to comment Share on other sites More sharing options...
JamesRich Posted July 21, 2011 Share Posted July 21, 2011 The harness is the same. I have a newer one that plugged right in. Ok then you could compare the wiring diagrams of a 94 and your 91 to make sure all the pins are the same. Unfortunately there are no 91 FSM floating around. The second thing you could do is cross your fingers and plug it in. James Link to comment Share on other sites More sharing options...
Kingman Posted July 21, 2011 Share Posted July 21, 2011 I've noticed no difference without the VSS wired in other than the cruise control won't work. Driveability hasn't changed any. The little differences *shouldn't* matter much when it comes to the ECU. MY1PATH is running a Cali ECU in his Federal Pathfinder and the only downside is the CEL is on due to there not being an exhaust temp sensor. The O2 sensor being different would likely cause an issue though unless you rewire if need be. You can check the wiring diagrams and pin out to see if they are the same. The speedometer on the round dash style is controlled by the sending unit/sensor on the transfer case, which interchanges with the cable style. Link to comment Share on other sites More sharing options...
JamesRich Posted July 22, 2011 Share Posted July 22, 2011 A lot of sensors are not important to how the engine runs. Jim Wolf has a diagram on their web site of how to strip down a maxima wiring harness to run a VQ30DE in an alternate application like sand rail or other off road vehicle. If you compare their diagram to the similar diagram in the maxima FSM they deleted almost half the wiring. I called them to ask how the ECU would like missing all these sensors and if they somehow reprogrammed the ECU to not need them. I was told the engine will run the same with or without these sensors. It will store codes but most people that put an engine like this in an alternate vehicle doesn't connect a check engine light. Only problem would be sorting through the extra codes if you had a driveability problem. Back to your problem, if you want to send your original ECU to get reprogrammed and the truck will run on the extra ECU you have now, just use it like that till your original gets back. James Link to comment Share on other sites More sharing options...
sewebster Posted July 22, 2011 Share Posted July 22, 2011 A lot of sensors are not important to how the engine runs. Jim Wolf has a diagram on their web site of how to strip down a maxima wiring harness to run a VQ30DE in an alternate application like sand rail or other off road vehicle. If you compare their diagram to the similar diagram in the maxima FSM they deleted almost half the wiring. I called them to ask how the ECU would like missing all these sensors and if they somehow reprogrammed the ECU to not need them. I was told the engine will run the same with or without these sensors. It will store codes but most people that put an engine like this in an alternate vehicle doesn't connect a check engine light. Only problem would be sorting through the extra codes if you had a driveability problem. Back to your problem, if you want to send your original ECU to get reprogrammed and the truck will run on the extra ECU you have now, just use it like that till your original gets back. James Cool PDF James! So it seems like the sensors you "need" are: -O2 -TPS -coolant temp -MAF -crank position Link to comment Share on other sites More sharing options...
Kingman Posted July 23, 2011 Share Posted July 23, 2011 That's what mine is running off of, actually minus the TPS. Link to comment Share on other sites More sharing options...
The_Magicians_Eye Posted July 23, 2011 Author Share Posted July 23, 2011 I tried the one I have out of the 95 (cali) and it ran good until it warmed up. Then it acted like it was flooding. I'd hit the gas and it would bog way down. If I floored it, it would eventually clear up and take off. Link to comment Share on other sites More sharing options...
Tungsten Posted July 23, 2011 Share Posted July 23, 2011 (edited) i was wrong about the VSS, it's actually a little black thing attached inside the mechanical speedometer it appears to me that the only difference is in the o2 sensor (and temp monitor for EGR on cali ECUs) your issue may be coming from the different o2 sensor Edited July 23, 2011 by Tungsten Link to comment Share on other sites More sharing options...
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