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03-28-2021, 01:42 PM | #1 |
Scooby Newbie
Member#: 520461
Join Date: Nov 2020
Location: Toronto
Vehicle:2004 WRX Silver |
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. |
03-28-2021, 02:02 PM | #2 |
Trust no one
Moderator Member#: 11170
Join Date: Oct 2001
Chapter/Region:
Tri-State
Location: NYC
Vehicle:02 RAV4 MT 15 WRX/11 CRZ |
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. |
03-28-2021, 06:54 PM | #3 |
Scooby Specialist
Member#: 29292
Join Date: Nov 2002
Chapter/Region:
SCIC
Location: Orange County CA
Vehicle:2004 WRX wagon silver |
could be a dead cell in the battery too, get it tested first
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03-28-2021, 07:43 PM | #4 |
Scooby Newbie
Member#: 520461
Join Date: Nov 2020
Location: Toronto
Vehicle:2004 WRX Silver |
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. |
03-28-2021, 10:51 PM | #5 |
Scooby Specialist
Member#: 125887
Join Date: Sep 2006
Chapter/Region:
NWIC
Location: Southern Oregon
Vehicle:2001 EJ207 V7 RSTi, Mica Blue |
What about crank angle sensor and cam angle sensor?
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03-28-2021, 11:23 PM | #6 |
Scooby Specialist
Member#: 110078
Join Date: Mar 2006
Location: Long Island N.Y.
Vehicle:02 Bugeye JDM STi OBP BLACK |
Did you just swap the motor or was it already running on the swap ?
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03-29-2021, 12:39 PM | #7 |
Scooby Newbie
Member#: 520461
Join Date: Nov 2020
Location: Toronto
Vehicle:2004 WRX Silver |
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? |
03-29-2021, 03:28 PM | #8 |
Scooby Specialist
Member#: 459287
Join Date: Dec 2016
Chapter/Region:
VIC
Location: Vancouver BC Canada
Vehicle:1998 JDM Impreza STi V4 GF8 White |
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03-29-2021, 08:57 PM | #9 |
Scooby Newbie
Member#: 520461
Join Date: Nov 2020
Location: Toronto
Vehicle:2004 WRX Silver |
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03-30-2021, 01:45 AM | #10 |
Scooby Specialist
Member#: 110078
Join Date: Mar 2006
Location: Long Island N.Y.
Vehicle:02 Bugeye JDM STi OBP BLACK |
Have you tried to start it on the usdm ecu ?
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03-30-2021, 05:59 PM | #11 |
Scooby Newbie
Member#: 520461
Join Date: Nov 2020
Location: Toronto
Vehicle:2004 WRX Silver |
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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03-30-2021, 09:08 PM | #12 |
Scooby Specialist
Member#: 110078
Join Date: Mar 2006
Location: Long Island N.Y.
Vehicle:02 Bugeye JDM STi OBP BLACK |
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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03-31-2021, 01:33 PM | #13 | |
Scooby Newbie
Member#: 520461
Join Date: Nov 2020
Location: Toronto
Vehicle:2004 WRX Silver |
Quote:
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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04-01-2021, 09:28 PM | #14 |
Scooby Specialist
Member#: 110078
Join Date: Mar 2006
Location: Long Island N.Y.
Vehicle:02 Bugeye JDM STi OBP BLACK |
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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04-22-2021, 02:16 PM | #15 | |
Scooby Newbie
Member#: 523836
Join Date: Apr 2021
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Quote:
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04-22-2021, 06:22 PM | #16 |
Scooby Newbie
Member#: 520461
Join Date: Nov 2020
Location: Toronto
Vehicle:2004 WRX Silver |
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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