Not really sure where to go with this next... (intermittent no start/power loss)

[Mysteron35]

One small thing that happened to my car a few years ago that caused similar issues that you could check.

The wiring to one of my injectors was loose/ broken.

I’d spent a lot time trying to track the problem down, car had also spent time at a local specialist who also failed to find the problem. One day I was looking around the engine and touched the plastic injector loom cover and the car started to misfire. It turned out that one of the wires was broken and just moving it by hand could make the engine run rough or smooth.

It may not be your issue but it’s easy to check.

steve.

[oceansize]

I've data logged my vanos inlet actual vs dme values in the past.

At idle the DME value sits at 60 while actual hangs very close. Under load is when you will see variances and I will say from memory that something like 98% of the time my actual vs DME was within 2 degrees under load. I had a few spikes where the difference got as high as 4 degrees.

[ATB88]

I've data logged my vanos inlet actual vs dme values in the past.

At idle the DME value sits at 60 while actual hangs very close. Under load is when you will see variances and I will say from memory that something like 98% of the time my actual vs DME was within 2 degrees under load. I had a few spikes where the difference got as high as 4 degrees.

So, now this bothers me even more. Why is your DME asking for 60 at idle, whereas mine always asks for 51.20, while my actual idle's at 60, which is way outside the allowable deviation range?

[oceansize]

So, now this bothers me even more. Why is your DME asking for 60 at idle, whereas mine always asks for 51.20, while my actual idle's at 60, which is way outside the allowable deviation range?

The commanded values at idle should be:

intake: 60
exhaust: 0

Anything else at idle is incorrect. Do you have the ability to log to a file your commanded vs actual values?

[Redline]

Called dr Vanos and besian and they said nothing to be alarmed, using a foxwell nt530 scanner. Dr. Vanos said they get that reading on every car they test...idk.

only code that it keeps throwing is the code 69 engine temp plausibility after it has the starting issue. No other code. And no freeze frame data either. Monitoring all sensors they are as they should be even before cranking and it still does it. Either I have a lazy cam sensor. Or my DME is at fault.

ive seen on some forums people report the code 69 shows up for unrelated reasons? Even with Vanos issues. Just sucks I have nothing to work with here.

amd at idle inlet is 60° exhaust is 0° exhaust moves with throttle input. Driving around inlet barely changes if at all and seems stuck at 60° while exhaust moves around...

[Redline]

Update

Installed new crank sensors, cleaned throttle bodies and ICV.

Problem still there

ive replaced everything.

lol bmw dealer doesn’t even want to deal with it 😂

so this leaves the Vanos solenoid/valve body, DME, engine wiring harness as the only parts on this engine that haven’t been replaced. Fuel pump was replaced a few years ago but with a gauge on it it tests good. I’m at a loss.

hell only thing left engine-wise is head gasket, main bearings and piston rings. Everything else mechanically has been done, bearings and all....FCP euro loves me and I guess I have the only s54 with a lifetime warranty by this point...

so what do?

[SteelGreyM]

I understand your frustration. I think every single M3 owner has at least *something* on their car they just can’t figuire out. Yours unfortunately is the last thing people want.

My vote would be for wiring harness. I’m intrigued by what Steve had to say earlier. I’d follow every single line all the way down. Or just shell out the cash for a new one and install it.

[Redline]

I understand your frustration. I think every single M3 owner has at least *something* on their car they just can’t figuire out. Yours unfortunately is the last thing people want.

My vote would be for wiring harness. I’m intrigued by what Steve had to say earlier. I’d follow every single line all the way down. Or just shell out the cash for a new one and install it.

Checked all pins/connectors/continuity on harness when I had it all apart last weekend....tried the old school wiggle test too. Good contact and no issues with the harness from that I can see/test. This sucks lol.

i will say I gained a full 8mpg more after doing the same driving after fixing (throwing parts at it) everything. It’s up to 24 highways now, beating on it around 19 mpg.

[Redline]

Still haven’t figured it out. Only code I keep getting is code 69 engine temp plausibility. Temp is always in the middle or just barely left of middle.

when I have the hard start/long crank right after start the Vanos is noisier than usual. When the car is sluggish I can hear the Vanos rattle more prevalent inside the car around 2500 rpms behind the dash even on highway speed. Sometimes will have chain rattle on startup if sitting. (Guides are new, Probly tensioner)

when car acts Normal, starts fine, pulls strong. Engine is quieter and less noise from Vanos/no rattle.

rattle behind dash sketched me out like it was my rod bearings but revving it stationary or driving by a wall in gear as well as using stethoscope it’s Vanos all day long, not the marbles in a tin can rattle but just louder than it should be.

[Arith2]

Through this, you posted a bunch of random things going wrong and it just seems sporadic. I'm voting the DME or a CAN issue.

[Redline]

Through this, you posted a bunch of random things going wrong and it just seems sporadic. I'm voting the DME or a CAN issue.

the parts I replaced were half throwing parts at it and half verified failures. Just odd of it were the DME, why haven’t any of the old faults come back after part replacement?

Still not ruling out the DME though. Wish I had a donor car I could swap with or might just buy an EWS deleted DME to try out...idk.

only other issue with the car is the LCM stopped recording mileage at 300,000km so have a data filing difference code between that and the cluster. No tamper dot.

[Redline]

Update...

it’s currently 75° here. Car has been sitting all night. Checked temps before startup and notice the following;

coolant temp engine 25°c
oil temp engine 25°c
coolant temp radiator outlet 23°c
intake air temp ((( 37°)))
ambient temp 23°c


Soooo maybe the really high IAT reading is causing my starting issue? Doesn’t it cause it to pull timing?

Maf was replaced last year with a new Bosch unit. Wiring is good. Or is it normal to read higher than ambient when fully cold and car in the shade? Might explain my heat soak feeling/lack of power I’ve had.

as soon as I start it drops to 32° for IAT and stays there


thoughts?

[Redline]

Anyone?

[Obioban]

I'd try a different DME. It seems like they're often the cause of inexplicable issues.

[maw1124]

I didn't read the entire thread, so please excuse any redundancies here, but...

Do these cars have an engine temp sensor and/or did you change that already? There's really no way the intake air can be 15*C off, so whatever that sensor is, I'd replace it. If that's the DME, is there some reflash you can try or have you done so already?

maw