Help! Intermittent starting woes

[upallnight]

Originally Posted by enzof355f430

Is that a question or a statement?
-Matt

Must be a statement since there isn't any question mark.

[enzof355f430]

Sounded as though it may be a question, and since I don't believe it is as easy as just jumpering the relay, I assumed you were asking.
-Matt

[upallnight]

That starter relay just supplies 12 volts to the starter solenoid. The starter solenoid is what supplies the 12 volt 80 amps to the starter to turn the engine over. That is why there is always a heavy wire from the battery to the starter. The heavy wire supplies the power, but the starter solenoid has to be energised before it can provide the power to the starter.

I have hot wired car with just a thin wire from the starter solenoid to the battery.

[deuchant420]

Update: not solved
I got a new key from the dealer, everything was good for about a week and then once again....came out from dinner out and wouldn't start. I listened carefully and it seems like the first time i turn the key there is a distinct click which sounds like it's coming from the starter like it doesn't have enough power to engage. then on subsequent tries there is no noise at all. this last time it started after a few tries. then the next day i went to start it and it started, but it went into limp mode and threw 10 different codes at once. I had my obdII code reader with me so i logged the codes and erased them. It has started and run fine for the last couple of days. The codes seemed pretty random, 1 for the thermostat, 4 for the vanos solenoids, and the others for fuel pressure and cam and crank sensors.
I have replaced all of the cam sensors, cleaned and replaced O rings on the vanos solenoids already and it has a new thermostat and sensor. All of which have been working for 5-6 months with no issues.
Could a bad crankshaft position sensor be causing all of my starting issues? it seems unlikely to me.
I'm hoping the next time it doesn't start I will be in a position to test the starter relay and the voltage to the starter solenoid. Every time it's done this I've been out somewhere with no access to tools or equipment. One thing I have noticed is that it seems to occur when I have driven and stopped at several places within a short time period, like going to several different stores in an hour.
thanks

[jfoj]

Without seeing the OBDII codes it is kind of not helpful. If you can provide the Pxxxx codes there may be something common for these.

I did not re-read the thread from the beginning, but this is sounds like maybe a bad starter or bad ground somewhere.

Maybe you sorted these, maybe you need to check these again.

I would keep a Voltmeter in the vehicle and for the next no start situation verify the Voltage from the engine block to at least the under hood positive jumper terminal.

Ideally you would be able to measure the power to the starter, not sure if this is accessible or if you would need to put a temporary jumper on the starter positive terminal for testing.

[CapeX5]

I agree with JFOJ. This sounds like a textbook bad battery scenario. I will tell you I just replaced my alternator and the battery light was not on. I had my scanner hooked up looking at info while engine was running and saw that I had only 11.8-12.2 volts. If I hadn't had scanner on, would have had no idea I had lost alternator or it would have happened on side of road. Check voltages while running. Easy to hook up wires with alligator clips to battery posts in engine compartment and have your multimeter inside while you either operate the car or just idle. Check these things first.

[jfoj]

I am assuming the battery was ruled out as a problem already, but was more leading to a bad connection. This being said I have seen batteries with bad cells and/or bad internal connections that have problems based on the battery warming up during charging or the car will need a jump start once with a while, but once jump started the car can work fine for hours or days.

Simple battery testing can rule out this as a problem.

But bad BST cable, bad engine to body ground, bad/loose connection at the under hood jump start connection or even the starter.

Bad starter, brushes worn.

Even seen ignition switch and/or EWS antenna around ignition switch.

Keep in mind the shade tree battery lead tester is using the headlights and honking the horn, usually a bad battery will show up doing this test after a no start. But if this works out fine, there could still be other connection problems in the path to the starter.

Voltage drop testing may need to be performed because you really need some connections under load to find they are bad. Search YouTube and/or the Internet for Voltage Drop testing ideas and methods.

Also remember to access the Hidden OBC for monitor Voltage as well. Not sure if the E53 has as bad a system to warn the driver there is a Voltage/Charging problem, but the E70 really SUX about notifying the driver there is some sort of Voltage problem.

[deuchant420]

I agree with the tests suggested. I'm leaning toward bad ignition switch, EWS antenna or maybe the EWS module. I did go through all of the positive and ground cables that were accessible. I need to do the voltage and relay tests next time it happens. I hate electrical gremlins!

[deuchant420]

MORE STARTING WOES
I'm having a similar problem now to another post. Crank, but no start on cold morning. I came out to start it on the first cold morning and it cranked, but wouldn't start. My first thought was fuel pump because I had a similar problem on my e46 where the pump died. However, I checked and was getting sub 11V at the fuse #47 and the same sub 11V at the pump itself. I hot wired the pump from the jumper terminals in the engine compartment which showed 12V and the pump started working. I then switched on the ignition and it started right up. I let it run for a few minuted to warm up and then hooked the wiring harness back up to the pump and it started on it's own. I drove it for over 500 miles that day with no issues. Then, the very next morning the exact same thing happened. I hot wired it again and got it running again. After warming up it starts every time.
Questions: should I have 12v at the fuse and at the pump?
could the sub 11v be a problem with the fuel pump relay?
could the sub 11v be keeping the pump from kicking on, on a cold morning or is it more likely that if it needs that full 12V that the pump is no good
could a pump that is going bad keep the car running for 1000 mile drive that I just did over 2 days?
as I understand it, the power goes through the relay to the fuse then to the pump. is that correct?

this no starting thing is getting old, thanks! ps the sub 11v was about 10.75ish volts

[deuchant420]

I also posted another thread regarding the fuel pump relay. Anyway, I did in fact drop the fuse panel and swap the fuel and horn relays and bam, it started right up. I checked voltage with the relay swapped and indeed it was now getting almost 12v to initialize the pump. Still not the full 12v while cranking, but my assumption is that it only needs the full 12v to get the pump going. It's hard to say, because I think the voltage readings may be off a little bit because the car was cranking and not running with the fuel pump un plugged. I also checked all the fuses in the E box and un plugged and plugged back in the relays for the DME and starter. It's possible that one or more of the relays was just loose causing a multitude of small problems. I did order a new relay for the fuel pump just to be safe. We'll see if time proves the solution right or there is something else going on. I will update later either way. I hope this update helps someone else who may be dealing with some of the same issues.
Cheers