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2G 95 MPI Relay

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talon_42o

15+ Year Contributor
95
0
May 24, 2006
Essex, ON_Canada
I have a weird issue with my car starting and electrical drain.

I recently had a 6 bolt swap done with ECMLink 3.0 installed.
The guy who did the work claims the car will only start if the MPI relay is grounded. He has two wires running from the relay to the car's chassis not sure what pins but I can take pics.

Now with that being said, he also disabled my clutch safety switch.

If I leave my engine fuse in overnight the battery will drain pretty significantly. Now this never happened before the swap, if you read my other threads on this you will understand the frustration. The car had a starting problem due too the wrong cam.

Well my friend thought it was a electrical problem and was testing wires from the ecu to the cas etc...

I need to know how too fix this "new problem"
I can't keep pulling this engine fuse all the time its becoming a pain in the ass.
 
He's rigged it up to where the MPI relay is sent power thru those 2 wires he hooked into. I don't have a 95 wiring manual but, if someone knows or you can find out what Pin# at the ecu supplies power to the MPI relay then you can probably fix that issue yourself. Normally the ECU supplies the power to the MPI relay. Since you have an aftermarket ecu installed, you have had problems. You are going to need a wiring diagram and a volt meter to figure out why the ecu is not sending voltage to the MPI relay.

Then after you have corrected that problem, you will have to do a "draw test" or let the car sit overnight. See if the battery is weak/dead. If the battery is weak/dead then you will have to get a test light and perform a "draw test". Start pulling fuses until the "draw" goes out. Then, track down that circuit the fuse was pulled from and that will help you isolate what the cause of the "draw" could be on your battery. Start with pulling the starter fuse and alternator fuse first, those will have the largest amount of "draw" on the battery.
 
The ECU doesn't send power to the MPI relay. It activates the relay by grounding it's coil to turn on the power to the ECU and the rest of the MPI circuit.

Which pins on the MPI relay did they ground? That will provide some clues as to what's broken.
It does sound like they have the MPI relay rigged up to leave the MPI powered up all the time, which will drain your battery
 
I happened to have an extra engine harness sitting next to me so I traced the wires out for you so there isnt any question as to where they go. Id bet that you have a stuck MFI relay. If replacing the relay doesnt work, PM me and Ill help you trace the problem.

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I happened to have an extra engine harness sitting next to me so I traced the wires out for you so there isnt any question as to where they go. Id bet that you have a stuck MFI relay. If replacing the relay doesnt work, PM me and Ill help you trace the problem.

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The FSM pretty much says the same thing but makes it clearer what they are for.

Pins 5 and 6 are what the ECU uses to activate the fuel pump power (pin 5) and the MPI circuit power (pin 6). Like most things the ECU activates they are active low, the ECU pulls them to ground to turn them on. Since pin 6 is grounded that would cause the MPI power to be on all the time.

Usually this is one of three things. Someone blew the transistor that pulls ECU pin 38 to ground. The ECU isn't seeing the signal from the ignition switch that the car is in RUN or START position, or the backup power from the "room" circuit isn't reaching the ECU. I guess the wiring between the ECU and these things could also be suspect.

If ungrounding the pin causes the car not to start, the MPI relay isn't stuck.
 
OK so should I inspect the ecu for damage? I know we messed with a bunch of wires at the power transistor and near the ecu... but the ecu would start in a 1997 tsi awd no problem so i'm doubting its the ecu.
 
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You never know until you finish diagnosing. If the ECU works in another car I'd start checking to see if the wiring is good and if you see 12v at ECU pin 82 from the ignition switch when it's in RUN or START.

One way to check the wiring between the MPI relay and the ECU is to see if you see 12v at pin 38 when the the ignition is off. (after you fix the cut wire and hook the MPI relay back up to the ECU)
That should drop to 0v when you turn the ignition on and activate the MPI relay.
 
Did you ever find out what was it? I have the same problem and it driving me nuts..

There is lots of diagnostic information in this thread, try using it and see if you can identify what's causing your problem.

You might be having the same symptoms but it remains to be seen if you have the same problem.
 
Problem was my eprom ECU the whole time its triggering the ignition intermittently I now have a 1997 eclipse gsx and with that ECU same problem so I am sending it back too ECM link where they inspected it back in 2011. LOL :hellyeah: :nono:

MFI relay trigger is faulty on pin 38
 
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