1G Intermittent Parasitic Drain + Idle Problems

[JayB12]

I've had a very intermittent parasitic drain that has plagued me for the last three months. I drive the car to and from work 7 days a week. Once every week or two I would come out and the battery would be dead, just enough that the starter will not move at all but the dash lights stay on after an 8hr workday.

I kept trying day after day to catch it with a DVOM, but have failed. It's driving me insane. Now the other day I installed a smim and minor battery relocation (to frame rail with 51R Battery). Drove the car a week like that normal but then the battery died one morning and I jumped it again and then halfway to work the car just decided it no longer wants to idle. Unless my foot is on the gas It will not stay running. Sometimes very rarely it will, but it will idle by itself at ~500 rpms for 2-3 mins then it stalls again. Fuel pressure is okay, no boost/vac leaks, Alternator SEEMS to be charging the battery, because after the draining of the battery it will charge it back up, but link shows battery voltage around 12v while running.

Can anyone help me. I'm going insane. I purchased a new alternator and am going to put it on right as soon as I finish posting this, but I'm afraid it will have no effect.

 

[92AWDHX40]

check all wiring connections to the battery and altenator, anything in the car draining the battery, any lights on anywhere.How are the grounds.

 

[Phantom DSM]

You should at least have around 14v without accessories or to low 13v with some accessories on while motor is idling. .
For parasitic drain put your Dvom on Amps and and probe on amp 10a socket on dvom. Pull negative cable and place red on cable negative and black on negative battery post while they are separated. You should have about .05 A or 50mv
If you have higher than that start pulling fuses untill you find the culprit draining. Otherwise you will have to check alternator and wiring , fusible link etc.

 

[JayB12]

More updates....

I think the two problems are seperate things, and I still have been unable to catch the parasitic draw. Every time I check it is normal.

The idle issue I had fixed by just turning th biss out about 2 full turns the car went back to idling like normal, then about a week later started idle surging slowly, after a few days it was always idle surging and doing it quickly. I hooked up link and set the screw back down until ISCPosition was 28-30 again. Ran fine for about three days until it went back to the low idle, stalling routine. I reset the biss again, getting the car to idle normally again and just today it is starting to surge slowly and ilde at ~1400.

-Base IGN timing good
-Mech. Timing Good
-ISC tested good
-NO Boost/Vac Leaks
-Did the "free" FIAV Blockoff
-Checked ECU for burn marks/weird smell, Nothing seems unusual

I am stumped...

 

[JayB12]

Another update if anyone can help:

Drain now happens all the time, it's the MPI relay, it was coming on/off with the key out. Now it is always on while the car is off unless the battery is out.

Anyone have a circuit diagram for the MPI? All the threads that have it have no working pictures.

 

[JayB12]

Also, if I unplug the C-59 connector to the ecu, the relay goes off. But unplugging C-60 has no change.

 

[mercaholik]

Sounds like a bad ecu, time to pull it and inspect it. If the caps leaked then that could explain the irratic idle and clicking mpi relay, and I had a similar parasitic drain then crank no start. I went thru some diag and found the ecu the culprit. And I too looked at the circuit board and didn't really see anything like the pics of bad ecu's no real smell either, but swapping it out for a repaired one solved all my issues.