[Thatguy93]

I recently purchased an 07 e90 335i with a build date of 10/06 for a project car. I bought it in the no crank no start condition but I've gone through almost everything i can think of and the problem hasn't changed.

Ive gone through all of the positive battery cables from battery to starter and everything has 12.7 volts, little to no corrosion, and a solid connection. Ive pulled and had the starter tested with no issues. The spark plug tubes did have about two inches of water in them between cylinders 3-6 however the water appeared to be from the car sitting rather than something internal. I've pulled the valve cover and looked at the oil but nothing seems to indicate any issues there. I changed the plugs along with the valve cover gasket as well.

The car has been repossessed in the past and definitely is without the original key. I only have one key and the fob buttons do not work. The internal valet key isn't even cut. I looked up the vin and it did not come with factory comfort access. It does however bring the car to accessory and all of the dash lights do come on as well as the stereo, windows, and blower motor. None of the fuses are blown and the only issue with the fuse box is a missing relay for the secondary air injection pump but thats on order. The battery has also been replaced with non oem but I've registered it with my foxwell reader.

Im getting the following codes:
AOAA
AOB2
AOB4
2DEC
2A17
5DA3
5D93
D373
D364
5DF7
5DF4
A669
A092
9CBD
9CBE
9CC4
9CCE

[kolhozbrothers]

Your starter is trying to start but won't turn over? I can hear it click when you pressed the start button.
Try turning your engine manually (crankshaft bolt) and see if it will turn. If the starter is good and is getting power, the engine may be hydro-locked.

[HiRev335i]

That's a lot of water in the spark plug tubes try pulling the plugs and then see if it cranks over if any water in there it'll expel as its cranking over if it is hydro locked

[Emilime75]

Originally Posted by kolhozbrothers

Your starter is trying to start but won't turn over? I can hear it click when you pressed the start button.
Try turning your engine manually (crankshaft bolt) and see if it will turn. If the starter is good and is getting power, the engine may be hydro-locked.

What he said. Can definitely hear what sounds like the starter trying to engage.

Also, water doesn't get into the spark plug tubes from "just sitting". This thing could've been flooded, or someone was very careless while washing the engine.

[Thatguy93]

Got a chance to look at it yesterday and turned the crank no problem. I jumped the starter with a remote start switch and the engine turns without issue so I'm pretty sure its not locked up at all. I also had my friend crank it while i checked for voltage on the starter and it looks like when the ignition is engaged it drops from 12.4 volts down to 6 and the battery drops from 12.4 down to 9. This only happens briefly as the starter attempts to engage. Once it disengages the the voltage comes back up to 12.4. I changed out the starter as well and the same thing keeps happening. There is only one ground left I haven't checked and i think its near the rear passenger wheel well. Other than that I'm thinking the issue might be with the car/dme/key.

[kolhozbrothers]

That's great news!
If the issue is DME/CAS/key, I can help you.

[Thatguy93]

So far the same issue keeps happening. The starter and battery keep losing voltage upon pressing the ignition. I've only done a quick run through with inpa and the dme/key/cas all seem to come back with no issues when i run diagnostics. I have been wondering if this could be from the IBS on the negative terminal. I've read that it must be properly coded to the dme and it can be pretty fragile. The battery it had in it was clearly one from auto zone and by the state of the compartment, i'd bet it was installed pretty roughly.

[gbalthrop]

Originally Posted by Thatguy93

[1] So far the same issue keeps happening. The starter and battery keep losing voltage upon pressing the ignition.

[2] I have been wondering if this could be from the IBS on the negative terminal...

1) When you say "the Starter & Battery keep losing voltage upon pressing the ignition" are you actually measuring battery voltage BEFORE pressing the START button, and then again AFTER pressing the button? If so, WHERE are you measuring voltage, and HOW?

The Starter effectively applies a "Load Test" to the battery on each engine start. A battery with a "bad cell" or internal fault can charge to 12.5+ Volts with a battery charger, show that Voltage when measured with a Multimeter, and then just click the Starter Solenoid and NOW read ~ 10V when measured with a Multimeter. If THAT is the type of "losing voltage" that you are experiencing, please describe in detail WHAT you are measuring and WHERE. Measure BOTH at: (1) the battery posts in boot, and (2) the Jumpstart Terminals under the hood, for reasons explained below.

You say the battery is new, and you also say in first post: "Ive gone through all of the positive battery cables from battery to starter and everything has 12.7 volts, little to no corrosion, and a solid connection." Are you aware of the "Transfer Points" forward of the Lower-Front of the battery?
https://www.newtis.info/tisv2/a/en/e...ble/1VnXWUgICS

Those can corrode or rust and result in insufficient current transmission from battery to Starter (or Jumpstart B+ Terminal) via the larger Red Cable. The Cable & Transfer Point that serves the Starter, Alternator & Jumpstart Terminal, is different from the cables that supply the DME or the JB and all Instrument Cluster operation, CAS, radio, etc.

2) As I understand it, the IBS (as used on the 2007 model) simply reports Battery Voltage and Temperature to the DME via the BSD bus. That data is used by the Power Module to calculate Battery SOC (State of Charge) and SOH (State of Health) and is used by the DME to control CHARGING of the Battery once the engine and Alternator are operating (which ain't happening for you at the moment).

I am NOT aware of any way a faulty or disconnected IBS can prevent Starter Cranking, assuming the new, healthy battery is properly charged and the B+ cables from the battery to the starter are capable of carrying sufficient current.

BTW, you don't say anything about checking GROUND cables, either Battery (-) to Chassis, or Chassis to Engine Block. Check the Battery Negative Terminal to Chassis for anything loose, and then put a jumper cable from the Jumpstart Chassis Hex stud to a substantial piece of clean metal on the engine (Bolt-head, etc.) as a supplemental ground strap.

George

[dpaul]

Originally Posted by gbalthrop

I am NOT aware of any way a faulty or disconnected IBS can prevent Starter Cranking,

Put a jumper cable from the Jumpstart Chassis Hex stud to a substantial piece of clean metal on the engine (Bolt-head, etc.) as a supplemental ground strap.

George

George is correct:
1) IBS is not your problem
2) Do the grounding test he suggests, it is the most direct way to test relevant ground

[Thatguy93]

Been a little while but i've done some more diagnosis with no new results. The transfer points forward of the battery don't have any visual corrosion. I went ahead and replaced them as well and it didn't change anything. The battery ground looks brand new and untouched and has a clean/tight connection to the body. I also replaced the ground strap with a brand new original one as well as tried to use a supplemental ground with a jumper cable and still no change.

When I remove the plugs and coils I'm able to get the starter to turn the engine without issue but as soon as i put them all back in the same problem happens and the voltage at the starter drops again. I have followed the starter switch wire all the way back to the JBE with zero voltage drop and the proper 12 volts when the ignition is keyed. Could it be that the water around the coils caused a short somewhere further into the electrical system? It's worth mentioning that someone has definitely gone through the fuses and relays before me because it was a puzzle of wrongly placed fuses or fuses that were missing all together. I have since replaced them all. The blades on the fuses looked burnt but none of them had actually blown.

On the battery I have measured the voltage from the terminals, various places on the BST, the forward transfer points, and on the jump start points under the hood with the same result. I have 12.4 volts, it drops to 9 volts when the starter engages, and then goes back up to 12.4 volts again when the starter disengages at every point on the positive cable up to the starter. On the starter I'm measuring voltage off of both studs. Im measuring it by watching my multimeter as a friend keys the ignition. Could it be as simple as not using an OEM battery?

In the bentley manual it says that an issue with the mechatronic unit could cause a no start condition but I'm hesitant to open the transmission up before I'm sure its my issue. The sleeve is not leaking and the plug for the mechatronic unit is undamaged.

[enriqxxx]

And how did you stay with your car?. I have something similar. Remove spark plugs and strap. He starts normally. but when you put the spark plugs and when you want to start the engine stops. I must turn it over and over with a key many times and loosen again