M62tu Not Starting All of a Sudden

[dannyzabolotny]

Thanks for the diagram! I'll definitely check it tonight with my friend.

[geargrinder]

Btw there are other sensor and driver ground pins on the other connectors IIRC but you'd need to pull the whole pinout to confirm that... On a tablet so harder for me to link the WDS page for you.

[jp5Touring]

Long shot,but kinda sounds like bore-wash. The I6 its not uncommon for this,don't know about the V8.

[JimLev]

Yes, way too much starter fluid.

[dannyzabolotny]

Long shot,but kinda sounds like bore-wash. The I6 its not uncommon for this,don't know about the V8.

How does one fix that? I do know that the injectors have been firing some gas into the cylinders because all of the spark plugs smelled strongly of gas when we pulled them last night.

[geargrinder]

It's not a known and easy to replicate thing in the V8s it seems. Might be possible but not like with M54s where it's way too easy to induce. The solution is healthy squirts of oil in all cylinders overnight to try to restore the ring seal.

Theres always the question of what caused the first no start issue that led to it getting borewash, maybe in this case the low voltage?

[peter540]

I'm going to ask a stupid question - did you pull the fuel pump fuse when you did the TCG job? If so, did you put it back in?

I know this wouldn't have anything to do with the electrical issues all of you are discussing, but still worth checking that you've fully returned everything to operational state.

--P

[dannyzabolotny]

I'm going to ask a stupid question - did you pull the fuel pump fuse when you did the TCG job? If so, did you put it back in?

I know this wouldn't have anything to do with the electrical issues all of you are discussing, but still worth checking that you've fully returned everything to operational state.

--P

Yeah I did that, but I put the fuse back in. I've also verified fuel pressure at the rail multiple times, it always goes past 40psi upon every attempt at starting. The fuel pump is definitely running.

[Mach540]

I'm going to ask a stupid question - did you pull the fuel pump fuse when you did the TCG job? If so, did you put it back in?


--P

It did run at first start, so unless it only ran for 5 seconds, that shouldn't be it.

Danny, it did run for more than 5 seconds, didn't it?

Edit:
He did report 40psi fuel pressure, so that shoots down that theory.

[Mach540]

It's not a known and easy to replicate thing in the V8s it seems. Might be possible but not like with M54s ?

Are the M54s Alusil like the M62s?

[dannyzabolotny]

It did run at first start, so unless it only ran for 5 seconds, that shouldn't be it.

Danny, it did run for more than 5 seconds, didn't it?

Edit:
He did report 40psi fuel pressure, so that shoots down that theory.

I ran it twice, each time for a few minutes. It ran fine and didn't indicate any problems aside from the CEL for P0348 and something else on the second run. After that it just wouldn't start... nothing obvious changed in those few minutes.

Are the M54s Alusil like the M62s?

I think they are?

[purplecty]

Try a battery nap? Maybe disconnect MAF and try starting it?

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[Kenny1958]

I ran into a no start on mine when i first fitted the blower and continued tries just made the situation worse. What i did was pull the relay for the fuel pump and turned it over, it then started but ran only momentarily until it used the juice in the bores.

[itsbrokeagain]

What IS the required fuel pressure for the M62? When my fuel pump crapped out, at ignition on it would make 40psi but kinda slow. Second I went to crank and run it would drop to 10psi and the motor would just stumble and bog or stall.

It had enough life to barely pressurize the system, but then it would be overwhelmed. In addition to the low fuel pressure, it wouldn't atomize correctly and I had pull the plugs and clean them when I got it back to the shop. (It broke in front of my house and hada do the pump in freezing cold February in the street)

[Mach540]

Good point. My 540 has ~50 psi running.
40 psi might be easy for a non running engine , but once it starts moving fuel it might not be able to maintain enough pressure to properly work

[TheAngryBear]

Bentley 160-13
All E39: 3.5 +/- 0.2 bar (50.76 +/- 2.9 psi)


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[geargrinder]

Are the M54s Alusil like the M62s?

Yeah supposedly the M54 thing is down to some fussy rings they have, doesn't seem like the M62TU suffers from that. Or maybe there's better splash from below on the V8 so it can restore the oil film or something. Who knows.

Good point. My 540 has ~50 psi running.
40 psi might be easy for a non running engine , but once it starts moving fuel it might not be able to maintain enough pressure to properly work

Yep. Volume vs pressure. It can make pressure at no volume but can't sustain volume once the demand increases. As I thought that one over i wasn't sure about if it'd really manifest that way, due to the return-circuit type FPR, but no it would. In essence with a dying fuel pump, the FPR would have the return line nearly closed up even at no demand, so there'd be no headroom for when the injectors start drawing. Like in imaginary made up numbers: if the FPR return is normally 95% wide open at idle (returning almost all the fuel) for a good fuel pump, on a failing pump, it might be 95% closed, which would allow it to get to pressure but wouldn't have anything left once the motor needs actual fuel.

A potential failing-pump test could be to put the gauge on the rail, and then carefully add 10psi to the FPR vac line and see if the fuel pressure ramps up 1:1 linearly. If it doesn't, then either the pump or FPR is kaput.

[purplecty]

https://www.newtis.info/tisv2/a/en/e...th-drive-line/

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[dannyzabolotny]

Alright so I did a bunch more troubleshooting tonight.

The initial compression test showed everything as quite low... ranging from 35 to 55psi at most. Once I added some oil to each cylinder, the values all shot up to around 120psi... interesting. After that, I put everything back together, turned the key, and it ran! For a short bit. Then it died.

Now it's back to having the same symptoms as before but now if I keep the key in the start position for 10-15 seconds it tries to fire up and I can hear it running, but then it switches off abruptly like somebody flicking a switch. I assume the X5 DME has some kind of failsafe where it switches off the ignition if the engine doesn't start within a certain amount of cranking, likely to avoid frying the starter. It does have the "one-touch" start where it'll keep cranking once you put the key in the start position. This is repeatable and it does it consistently, so it's not a one-time fluke.

Fuel pressure at the rail is a maximum of 45psi from what I've seen. I smell gas everywhere, and there's some smoke when the engine runs, likely from all the oil I added to the cylinders.

So now I'm just wondering what the heck is going on. Could the fuel pump still be bad while appearing to put out adequate pressure at the rail? Hmmm. Maybe it's time to give the starting fluid another try with a friend cranking the engine.

[Mach540]

I'd concentrate on the compression issue. Maybe this truly is the classic "bore wash" scenario.

[TheAngryBear]

With those compression numbers I flashed back to this thread
https://www.bimmerforums.com/forum/s...in-replacement
Maybe not fully tightened and slipped?


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[geargrinder]

I'd concentrate on the compression issue. Maybe this truly is the classic "bore wash" scenario.

Agreed. Sounds very like that.

- - - Updated - - -

Thanks for the diagram! I'll definitely check it tonight with my friend.

Did you ever do this? i.e. check the DME's supply voltage vs the INPA displayed voltage?

[purplecty]

Any updates?

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[dannyzabolotny]

Yeah, me and the owner of the X5 mutually decided to get it towed to a local BMW specialist for further diagnosis, as I was not able to get it running. I tried adding oil to each cylinder which did improve the compression numbers, but it did not make the engine run. I'm thinking the bore wash/gas in the cylinders is just a byproduct of whatever the root problem is.

Before sending it off to the shop, I removed both valve covers and used the timing tools to verify that the timing was correct— with the crank locked at TDC everything looked pretty spot-on with the cam blocks.

For what it's worth, the shop has had the X5 for like two weeks or more, and they still haven't been able to figure out. So it definitely isn't anything obvious. Even though that's terrible, it makes me feel better, since it means I didn't screw up anything obvious.

[derrith]

Follow up to this thread for the poor soul in the future.

I had this same problem with my 4.6is went from running and driving to crank no start with apparent fuel pump turn on and spark but no start. It had been intermittent for a while and finally just stopped one day. Ended up being cam sensors. I had been getting intermittent cam sensor circuit codes but they would come and go.

I spoke with Danny and his issue ended up being the cam timing/cam sensor chopper wheels position.

m62tus look to sync cam and crank sensors signals on start and won’t run without.