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unknown electrical problem

883 views 5 replies 5 participants last post by  silverton 
#1 ·
Hi everyone, I swapped a JDM EJ205 turbo with AVCS into my 2000 Subaru Impreza outback sport and I've run into an issue.

The problem is that after it had been swapped and tuned for a month or two, all of a sudden it started having this issue, when I went to go start it up and let it idle to warm it up the car would idle to maybe about when it would be warm, perhaps even earlier. Then the car would seem to start to struggle to stay on like it started to have a rougher idle and you could tell the car was starting to die out (sound weaker). The gauges would drop to 0 then all electronics like my head unit, clock, and lights would dim and turn off, but the engine would still run for a few moments then die. I'm 100% the engine is healthy and it's not a fuel issue. it has a brand new AEM high flow fuel pump.

It has an AEM high flow fuel pump
tune on stock ECU( after all of these other parts were installed)
STI spark plugs
Grimspeed aftermarket TMIC
Brand new Interstate battery and 05 STI alternator( have been tested and are good)

This car was my daily and I've put so much money into doing the swap and other parts, and am starting to feel a little defeated by how it's doing right now. does anyone have any thoughts or ideas on how I could go about this? I took it to a mechanic because I really could not figure out the source and they think it might have to do with my ECU or wiring harness.
 
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#4 ·
Check the battery voltage (an accessory point like lighter is better) when it is idling low. Electronics usually will remain powered until you are below 11-10 volts, and this is far too low voltage at idle.

Now the low voltage is most likely a result of your low idle issue, not necessary the cause.
 
#6 ·
It's either the MAF or O2 sensors. Pretty much the only thing two things that will change how the car runs as it warms up.

Also could be noted that the car needs to be retuned for the summer blend fuel, if applicable to your area.
 
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