Kenny_Kline
Well-known member
I am having an issue with my ECU not being able to save my tune. I have ruled it out to an electrical issue in my car and believe it is related to another electrical issue I am having.
Basically, when ever I setup my global fuel settings, sensor type, etc. I click copy to ECU. It says it saves. But as soon as you disconnect the battery it goes back to the old settings it had in it from a previous car (I bought the chip used who had a speed density tune) It will copy over his tune/settings, the car runs great but at as soon as I disconnect power, it goes back to old settings. A friend of mine brought his ecu and his chip down today and we tried it out. Sure enough it does the same thing! And his is a running driving car with a known good ecu and chip. So that means my ECU and chip is fine. Can anyone explain this?
Some of you are wondering, why do you keep disconnecting the battery? Well, I have to to cut power off. I will explain. I turn key on, turn key off, take key out but everything stays on (dash lights, blinkers work, etc.) So I start pulling fuses to find out what is keeping it on. The MPI fuse kills the power. I put the fuse back in and the lights arent on sort of like it resets itself. Your probably thinking a bad MPI relay? Yeah I did too so I swapped the MPI relay with 2 other used ones (unknown condition but what are the chances they do the same thing?) I could swap a known good MPI relay as a desperate attempt but I feel I will get the same result based on these findings... I tested MPI relay for power at every pin with key off and only found 1 wire that goes to the battery/MPI fuse. I turn key on, key off, then test again. I am now finding 4 wires inculding the main power wire to have power. SO I start cutting each wire. The last one I cut, shuts off the relay but as soon as I hook the wire back up, dash lights are on. I figure its not an MPI relay issue and possibly a ECY issues because I disconnected the wire again from the MPI relay and its still putting out a 12v signal even with key off when its not supposed to be. If memory serves me correctly, its a white wire with rew stripe or vise versa and it goes back to a pin on the ECU directly according to schematics (I will have to refer to notes to confirm on what pin exactly). I am thinking bad ECU but yet, we just tried my buddies ECU and it does the same thing but doesnt do it in his car.
So with everything said and found, it sounds like a relay not shutting off killing power to ECu but what relay controls the ECU, if any? What further testing can I do? I obviously have an electrical issue in my car that could be related to not being able to save my tune in the ECU. This is just nuts. To add to it, when I hook up the oil pressure wire to sender unit, the oil press spikes to H and stays there even with car off. I disconnect oil press wire and it just lays dead, nothing changes. I pulled gauge fuse and that just shuts off the lights on the dash but MPI relay still has power on all the wires that shouldnt be when key is off.
Its a mess, I know. I feel I am going to have to bring this car down to a known good electrical guy unless someone on here can figure it out or give me other ideas. All I know is this is a mess and this is a problem that is unheard of.
I will do whatever tests are necessary to diagnose.
Discuss!
Basically, when ever I setup my global fuel settings, sensor type, etc. I click copy to ECU. It says it saves. But as soon as you disconnect the battery it goes back to the old settings it had in it from a previous car (I bought the chip used who had a speed density tune) It will copy over his tune/settings, the car runs great but at as soon as I disconnect power, it goes back to old settings. A friend of mine brought his ecu and his chip down today and we tried it out. Sure enough it does the same thing! And his is a running driving car with a known good ecu and chip. So that means my ECU and chip is fine. Can anyone explain this?
Some of you are wondering, why do you keep disconnecting the battery? Well, I have to to cut power off. I will explain. I turn key on, turn key off, take key out but everything stays on (dash lights, blinkers work, etc.) So I start pulling fuses to find out what is keeping it on. The MPI fuse kills the power. I put the fuse back in and the lights arent on sort of like it resets itself. Your probably thinking a bad MPI relay? Yeah I did too so I swapped the MPI relay with 2 other used ones (unknown condition but what are the chances they do the same thing?) I could swap a known good MPI relay as a desperate attempt but I feel I will get the same result based on these findings... I tested MPI relay for power at every pin with key off and only found 1 wire that goes to the battery/MPI fuse. I turn key on, key off, then test again. I am now finding 4 wires inculding the main power wire to have power. SO I start cutting each wire. The last one I cut, shuts off the relay but as soon as I hook the wire back up, dash lights are on. I figure its not an MPI relay issue and possibly a ECY issues because I disconnected the wire again from the MPI relay and its still putting out a 12v signal even with key off when its not supposed to be. If memory serves me correctly, its a white wire with rew stripe or vise versa and it goes back to a pin on the ECU directly according to schematics (I will have to refer to notes to confirm on what pin exactly). I am thinking bad ECU but yet, we just tried my buddies ECU and it does the same thing but doesnt do it in his car.
So with everything said and found, it sounds like a relay not shutting off killing power to ECu but what relay controls the ECU, if any? What further testing can I do? I obviously have an electrical issue in my car that could be related to not being able to save my tune in the ECU. This is just nuts. To add to it, when I hook up the oil pressure wire to sender unit, the oil press spikes to H and stays there even with car off. I disconnect oil press wire and it just lays dead, nothing changes. I pulled gauge fuse and that just shuts off the lights on the dash but MPI relay still has power on all the wires that shouldnt be when key is off.
Its a mess, I know. I feel I am going to have to bring this car down to a known good electrical guy unless someone on here can figure it out or give me other ideas. All I know is this is a mess and this is a problem that is unheard of.
I will do whatever tests are necessary to diagnose.
Discuss!
