2G MPI Relay

[Z3r0to1]

This'll be a fun story to tell...so I was travelling down the highway, normal response and noises from the engine and car. The further I went on the drive however, it felt like the car just kept giving up more and more. I started to hear a buzzing noise coming from the MPI relay, and throttle response was damn near zero. When I began to pull over, the car died due to shifting into neutral. Once this happened I tried to turn it back over, and lights flickered. Immediate thought process was the alternator. After getting back home and charging the battery, the buzzing continued when trying to start the car. I assume this is a sign of a bad MPI relay, but I would much rather have a discussion before going down a repair path only to find out I was wrong. Any other ideas?

 

[Bleakley]

Find out where the buzzing is coming from.
Not sure why you automagically assume MPI relay. Would be a bummer to change it out and it not do d*ck for you.

Super easy to test for a faulty relay. If the buzzing is relay, use a wiring diagram to diagnose it.
If it’s a ‘95/‘96 I can help.

 

[Z3r0to1]

Find out where the buzzing is coming from.
Not sure why you automagically assume MPI relay. Would be a bummer to change it out and it not do d*ck for you.

Super easy to test for a faulty relay. If the buzzing is relay, use a wiring diagram to diagnose it.
If it’s a ‘95/‘96 I can help.

So I dig some digging and felt the relays to feel which one it was, that's how I came to the conclusion of the MPI relay. Sorry, I forgot to include that beforehand. Anywho, it is a 95' so any insight you have would be greatly appreciated.

 

[pauleyman]

Mpi buzzing is a possible symptom of bad ecu. Quick visual check isnt a bad idea.

 

[motomattx]

My vote is bad ecu, or bad ground on the firewall or the ground below the ecu.

 

[steve]

The buzzing is usually caused by the relay not getting the proper voltage to operate. Several of the causes for that have been mentioned the first being make sure the battery is fully charged and the connections to it clean and tight. Measuring the voltage at the relay and the drop across the relay will help diagnose.

Your description sounds quite a bit like a dead alternator to begin with.

 

[Z3r0to1]

Just to provide clarity to the situation and an end to the thread, the issue turned out to be a grounding cable that had tucked itself away and then corroded. MPI relay ceased to buzz and now that issue is resolved.