AEM Momentarily loss of electronics

[cioc]

I've owned my dsm for 25 years, have had every bolt off and on the car turned by yourself truly. That being said, I cannot diagnose an electrical problem worth a damn and need help. The car wiring harness has been hacked thoughout the years, removing unnecessary circuits etc. The car runs on an AEM EMS V1. What happens is an intermittent loss of power. It feels EXACTLY like fuel cut however the tach signal drops in concert with the momentary loss of power. It can happen under boost...in vacuum...part throttle...full throttle. It happens in milliseconds. Sometimes I can't even look down quick enough to see the tach signal come back. Yesterday it happened 5 times during a leisurely cruise but sometimes it will take weeks to reproduce. Any ideas electrical gurus?

 

[6damian6]

loose cables at the battery?

 

[cioc]

loose cables at the battery?

I tried that. I've replaced the MPI relay, checked all fuses, even got some new yellow plugs because mine was missing the locking tab and verified all pins were seated properly.

 

[6damian6]

try a different power transistor

 

[1990TSIAWDTALON]

Hate to say as I have alot lately, good grounds to all components??? Make sure.

 

[Mello]

All the electrical, lights, radio, etc.; or just the EMS? Also what firmware version are you running, the last release or older?

 

[cioc]

I just had to order a new voltmeter to test all the grounding points. They appear to be fine, contacts cleaned no corrosion etc. This only happens with the ems. The car is completely gutted so I do not see any other momentary losses. My aftermarket gauges do not die momentarily so right now it's just the tack and engine. I tried logging the event but the ems data file gets corrupt I assume by the momentary loss of power. The ems is running version 1.19.

I have had power transistors go out on my in the past but when they fail in my experience it drops 2 cylinders. Could a faulty power transistor have this same effect?

 

[Vegas Smith]

I want to say this is familiar. I seem to remember a thread about an older version AEM that needed updates. I can't find the thread but it got pretty complicated. I would contact AEM. (They'll probably try to get you to upgrade).

 

[1990TSIAWDTALON]

Power the ems with a separate battery and try to log the event.

 

[jakelandry]

May sound dumb because its not AEM but my dsmlink ecu would drop out completely for a few mS like that. I know 1g cars are different but mine would drop the tac and completely reset the ecu. I had the caps replaced by ecmlink 3 years before it happened and they looked fine with no signs of corrosion or anything to that nature but I replaced them again and it solved my problem. That's literally the only thing I could think of that could cause a drop like that for just a few ms and luckily it solved my issue without trying 10,000 other things first. Know its a long shot, but faulty caps can cause flash signal drops like that.