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Old 03-28-2021, 01:42 PM   #1
Bluebieru
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2004 WRX
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Default Slow cranking + low voltage

Chassis: 2004 USDM WRX
Engine : JDM V7 Ej205 w/AVCS
Ecu: 2001 JDM Sti
THE CAR HAS A CRANK NO START (specifically no spark) CONDITION

My car has a whole list of problems and im trying to solve them 1 at at time. Rn the car wont start and while doing some logging on romraider I fould that my engine speed while cranking is about 114 rpm. From what I've read thats really slow and it should be closer to ~300 rpm?

While doing the test I've also noticed that my measured voltage will go from 12.5v at "Key On" to 7.5-8.5v while cranking. I thought my battery was dead so I used jumper cables to connect my car to another while it was running and my measured voltage went from 13.8v back down to 7.5/-8.5v while cranking.

What would cause such a huge voltage drop and such a slow crank speed? Would that be related to my ecu not triggering a spark for cylinders 3 and 4?
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Last edited by Bluebieru; 03-31-2021 at 01:34 PM.
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Old 03-28-2021, 02:02 PM   #2
Mulder
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Are you measuring that voltage directly at the battery posts? If so then you can rule out a voltage drop issue between the battery and starter.
Assuming a good fully charged battery, a drop like that would indicate a very high draw from the starter, either due to a problem within the starter itself or excessive drag from the engine. You can get an inductive ammeter to attach to the starter cable to measure the draw. Turning the engine by hand with a breaker bar on the crank pulley should give you an idea if it's turning freely or not. The no-spark may or may not be related, did you have the coils disconnected and perhaps plugged them into the wrong connectors? That would have the cylinders firing out of time.
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Old 03-28-2021, 06:54 PM   #3
subaru_gc8
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could be a dead cell in the battery too, get it tested first
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Old 03-28-2021, 07:43 PM   #4
Bluebieru
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The battery voltage and crank speed were both measured in romraider. I even removed my battery completly and tried starting the car useing jumper cables to a running car with the same outcome.

Also I can turn my engine pretty freely with a ratchet, I dont even need a breaker bar.

How can I test the starter for a very high draw?

Last edited by Bluebieru; 03-29-2021 at 02:32 PM.
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Old 03-28-2021, 10:51 PM   #5
Bluestreak03
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What about crank angle sensor and cam angle sensor?
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Old 03-28-2021, 11:23 PM   #6
D-Rodman
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Did you just swap the motor or was it already running on the swap ?
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Old 03-29-2021, 12:39 PM   #7
Bluebieru
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The cam and crank sensor are both new and the ecu is getting "a" signal ccording to romraider (i just dont know if its a correct signal). The car has not started since the swap.

Im wondering if a slow cranking speed could cause the cam sensor to send inacurrate signals to the ecu? Also how to I test the starter to see if its causing such a high draw?
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Old 03-29-2021, 03:28 PM   #8
Vancouver98STi
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V4 GF8 White

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Quote:
Originally Posted by Bluebieru View Post

The car has not started since the swap.
Are all grounds in place... and are they all making good contact?
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Old 03-29-2021, 08:57 PM   #9
Bluebieru
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Quote:
Originally Posted by Vancouver98STi View Post
Are all grounds in place... and are they all making good contact?
The starter ground and IM ground were scrubbed and reapplied and the 2 chassis grounds were cleaned yesterday. Continuity tests to the neg battery terminal are all 0-0.2 ohms
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Old 03-30-2021, 01:45 AM   #10
D-Rodman
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Have you tried to start it on the usdm ecu ?
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Old 03-30-2021, 05:59 PM   #11
Bluebieru
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Yes but that won't start either. It won't give me a spark on any of the cylinders, I'm assuming that's because of the missing tgv's on the jdm engine
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Old 03-30-2021, 09:08 PM   #12
D-Rodman
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No spark has to be a wiring issue, did you wire the avcs by repining it or did you buy an add on harness ?
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Old 03-31-2021, 01:33 PM   #13
Bluebieru
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Quote:
Originally Posted by D-Rodman View Post
No spark has to be a wiring issue, did you wire the avcs by repining it or did you buy an add on harness ?
I repinned it using a combination of the DS1 avcs install document on another thread, and these 2 pics I also found on anther thread
https://img.nasioc.com/i/hVwlA.jpg
https://img.nasioc.com/i/hVzJ7.jpg
I didnt remove the TGV wires from the bulkhead harness side so they terminate at the f61 plug to the ecu.

Can an improperly installed avcs cause only 2 of my cylinders for to trigger a spark?
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Old 04-01-2021, 09:28 PM   #14
D-Rodman
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It sounds like you are having a wiring issue, may want to trace your steps back and see if you can figure it out.
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Old 04-22-2021, 02:16 PM   #15
Clickedspider
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Default

Quote:
Originally Posted by Bluebieru View Post
Chassis: 2004 USDM WRX
Engine : JDM V7 Ej205 w/AVCS
Ecu: 2001 JDM Sti
THE CAR HAS A CRANK NO START (specifically no spark) CONDITION

My car has a whole list of problems and im trying to solve them 1 at at time. Rn the car wont start and while doing some logging on romraider I fould that my engine speed while cranking is about 114 rpm. From what I've read thats really slow and it should be closer to ~300 rpm?

While doing the test I've also noticed that my measured voltage will go from 12.5v at "Key On" to 7.5-8.5v while cranking. I thought my battery was dead so I used jumper cables to connect my car to another while it was running and my measured voltage went from 13.8v back down to 7.5/-8.5v while cranking.

What would cause such a huge voltage drop and such a slow crank speed? Would that be related to my ecu not triggering a spark for cylinders 3 and 4?
Did you ever get it to work?
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Old 04-22-2021, 06:22 PM   #16
Bluebieru
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2004 WRX
Silver

Default

For me it ended up being a bad engine harness. It was missing a ground near the passenger side IM along with various other damaged wires.

I replaced the engine harness and the car starts now. It still has a high idle (1500-2000 rpm) and passenger avcs sensor dtc but that's a whole other discussion.

Last edited by Bluebieru; 04-22-2021 at 06:32 PM.
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