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BMW 3-Series (E90 E92) Forum
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Strange Intermittent Starting Issues
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05-26-2022, 12:02 PM | #1 |
E82 Mudflap Ambassador
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Strange Intermittent Starting Issues
Cross posting from 1Addicts because this gets more traffic
So I started having issues starting the car and I'm stumped. I bought a new TYC brand starter off Amazon since it was well-rated. All was well for like a week. Started having issues again. Figured it was a faulty aftermarket starter so I dropped the cash on the Bosch, same thing (although it's partially alleviated). What's happening is the starter will turn strong for a second or two, then stop before the engine has a chance to start. This will happen like 1-5 times before I get a full solid crank and it starts. It's not always consistent though - I can get in and start it with an immediate strong crank 5 times in a row. Then the next 5 times I'll have to let it fail and retry before it starts (but it always does). Sometimes when it fails I can hear the starter continue to turn but it's not engaged with the flywheel On top of the starting, I hear a relay clicking from the passenger side of the dash when I try and fail to start it, and sometimes on shutdown after a drive. Maybe my CAS relay? I don't know much about that system. Battery is a relative new (few months) H8 lead acid that was coded and registered. Battery is at 12v and alternator charges fine around 14. Might have O'Reilly's load test them. Maybe looking toward my engine ground straps. It's a Florida car so it never saw salt but I've seen firsthand what the humidity can still do to metal. edit: found someone describing my exact symptoms and they needed a new CAS module, hmmmm
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Parents' 2014 528i - Mineral White/Ivory White - fully loaded Instagram @Andreys_128i and @Honda.Bito Last edited by desertman123; 05-26-2022 at 12:33 PM.. |
05-26-2022, 03:52 PM | #2 | |
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Quote:
In that List above, given just to get you to think of the "CIRCUIT" the current has to follow, you can eliminate the Ground Strap by simply connecting one end of ONE Jumpstart Cable to the "Hexpin" on the Right Fender/Wing under the hood, and the other end of that cable to a good metal bracket or bolt anywhere on the Engine. That cable then acts as a "Supplemental Ground Cable". If the Starter Cranks as it should with the Jumpstart Cable attached, but NOT when Cable removed, the Ground Strap at the Starter Motor (beneath the vehicle) needs replacement. The NEXT suspect is the B+ Transfer Point for the LARGE Red B+ Cable from the (+) Battery Terminal/BST to Outboard fitting forward of battery. That Transfer Point is particularly suspect if you had water in the Battery Well. When you replaced the Battery ~ a year ago, did you open the cover of the black plastic Transfer Point cover, and inspect for Rust? That Transfer Point can corrode/Rust to the point where current does NOT flow through it fast enough to power the starter sufficiently or hold the Solenoid "IN" to keep Starter engaged with Flywheel. The CAS Module is NOT an issue under your description. It ONLY provides current to activate the Starter Solenoid, NOT the larger-Amp current to crank the engine. There is no "CAS Relay" on the JB Fuse Panel. The CAS Module activates BOTH the KL15/Terminal 15 Ignition Relay, and the 30G or Accessory Relay when Ignition is switched on. If there is NOT enough current supplied by the Battery, either or Both of those relays could "Chatter" as the contacts close/open rapidly. If you currently have water in the Battery Well, the amount of current flowing through the Transfer Point powering the Starter COULD be affected by vehicle orientation. OK Amps if Nose Up. Starting issues when Nose DOWN and water covers transfer Points. You can also check to see what your "Voltage Drop" is during Starter Cranking. Normally, Voltage will drop ~ 2 Volts during the Second or Two that the Starter Cranks. If you measure 12.5V battery voltage (Multimeter at Jumpstart Terminals, using Scan Tool, Lighter socket readout, etc.) BEFORE Starter cranking, the System Voltage should drop to ~ 10.5V DURING cranking. BEFORE throwing any parts, I would suggest posting back with results of those tests. George |
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06-01-2022, 03:44 PM | #3 | |||
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Drives: '08 128i
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Quote:
I inspected my starter ground strap and the one that runs to the VC and they both looked decent, but replaced them anyway since it's relatively cheap and easy. Same change as the jumper cable test - seems a little better but it still does it. Quote:
Quote:
Voltage drop was normal, just as you described.
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My 2008 128i - Sparkling Graphite/Beige - Sport pkg - 6MT - Click me!
Parents' 2014 528i - Mineral White/Ivory White - fully loaded Instagram @Andreys_128i and @Honda.Bito |
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