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Long cranks
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09-09-2021, 10:40 PM | #1 |
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Long cranks
So i hav a 2011 335i n55 on cold starts the car starts as it should but once it's up to temperature or after it's been started multiple times it starts a while to start. It will crank 4-5 times before it starts. I'm running mhd stage2+. Also battery is new and starter is 3yrs old. Any ideas?
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09-09-2021, 10:57 PM | #3 |
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09-10-2021, 08:56 AM | #5 |
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It's always good to check ground straps. However, since you are getting good crank (just long), the starter (good condition) is getting the juice it needs from the battery (new).
We can also (probably) rule out the crankshaft position sensor since you are not getting any issues on cold starts. So, the next thing to investigate is spark and fuel. I would suspect something in the fule delivery. Are you getting any issues once the engine is running? Like rough running, missing etc.? If yes, it could be the High-Pressure Fuel Pump. It may or may not throw a CEL depending on the severity of misses. I would still check codes before throwing any money at parts. If the pump is OK, perhaps one of the injectors is acting up and it manifests itself when the engine is heat-soaked. |
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09-10-2021, 09:00 AM | #6 | |
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09-10-2021, 09:03 AM | #7 |
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+1 for ground straps. It's pretty easy to rule out. On your next cold engine, take a jumper cable and ground the engine to the ground plug in the engine compartment. If it starts right up, you may have a ground problem. You can check by measuring the voltage across the + terminal to the block and comparing it to the voltage across the + to ground terminal.
You can do just start with the multimeter, but the jumper cable gives you that immediate feedback that it's probably a grounding issue. |
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09-10-2021, 09:08 AM | #8 | |
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09-10-2021, 09:30 AM | #9 |
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He's suggesting to use a "Jumper Cable" as a "Supplemental Ground Strap". Just connect ONE jumper cable from "Hex-pin" at X166 Chassis Ground Point on Right Fender/ Wing to a good metal bracket, bolt, etc. on engine. That's the easiest/ quickest way to see if your ground strap under the car is OK.
However YOUR issue is when engine is WARM. You don't indicate what the RPM is during cranking, or how LONG (seconds) cranking occurs BEFORE engine fires. If Cranking RPM is NORMAL, then ground strap is likely NOT the cause of your issue. What you REALLY need is to read Fault Codes in DME & EKPS, and then to use proper Diagnostic Software (INPA/ISTA) to monitor Live Data during "Hot Cranking", or simply when turning on Ignition with hot engine. Monitor LPFP operation, AND HPFP or Rail Pressure, as well as DME Main Relay function. George |
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09-10-2021, 09:33 AM | #10 | |
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09-10-2021, 09:46 AM | #11 |
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Those codes are pretty telling... you have fuel delivery issues and your having to wait for pressures to build, hence the long cranks.
Start by monitoring the low pressure fuel pressures on startup, this should remain ~70psi range the entire time. Assuming low pressures are good the high pressure fuel pump is your next suspect. |
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09-10-2021, 09:48 AM | #12 |
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09-10-2021, 10:28 AM | #13 | |
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Starts not cold |
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09-10-2021, 11:09 AM | #14 | ||
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Your + terminal and ground are in a different location, but you'll get the picture below. Both are reading 12.51, so the block is properly grounded. They may be slightly different, but not much. |
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09-10-2021, 11:16 AM | #15 | |
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2) I would NOT call "3 seconds to start when warm "Long Cranks", at least until it gets worse. 3) The Code suggests that rail pressure is LESS than it should be during "Injector Release". That could be due to EITHER HPFP or LPFP issues on warm start, OR it could be due to an issue with a leaking injector. I assume you do NOT have any rough running immediately AFTER warm engine start, or dark smoke from tailpipes? 4) As "LAH" suggests, I would view Live Data of LPFP RPM, Temp & Amps during Cold Start and compare with same data during warm start, to determine if LPFP delivery is causing low rail pressure. 5) As for NO codes in INPA, have you checked ALL THREE: a) Fehlerspeicher; b) Infospeicher; c) Historyspeicher? The low pressure condition is ONLY Present/Active for a second or two during warm cranking, so "Inactive" in MHD. I would be surprised if a code did NOT appear in Infospeicher or Historyspeicher. Please let us know if it does. HistorySpeicher remains even after Fehlerspeicher is Cleared. George |
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09-10-2021, 11:19 AM | #16 | ||
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09-10-2021, 11:26 AM | #17 |
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09-10-2021, 11:31 AM | #18 |
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09-10-2021, 04:31 PM | #19 |
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Not sure how to post a video
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09-11-2021, 02:15 PM | #20 |
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Made bit of progress. Ram fuel quantity control flow and it failed saying i should replace electric fuel pump which is the lpfp
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09-12-2021, 01:56 PM | #22 |
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Nah i didn't this was plugs from April
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