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

[Zekarus]

Installed the new o2 sensors. Gas mileage and power are back...still have the starting issue.

that just leave both cam position sensors. And purge solenoid for what hasn’t been replaced lol. Or fuel pump check valve failing? Pump is 6 years old and about 80k on it...tested fine last 2 times I checked it though...

one step forward, nice! this jump start thing would lead me to check my alternator voltage. i would also check if your battery cables are tied properly and if any grounds are loose (unlikely).

Installed the new o2 sensors. Gas mileage and power are back...still have the starting issue.

that just leave both cam position sensors. And purge solenoid for what hasn’t been replaced lol. Or fuel pump check valve failing? Pump is 6 years old and about 80k on it...tested fine last 2 times I checked it though...

your numbers seem to be fine. i had a really bad head gasket with 4-8 bar (60-110psi i think) on a cold engine 🙃. and i have an US import 😀

[Obioban]

If all Else fails, consider replacing the ECU. I was chasing weird issues with the M3 wagon for a while and it ended up that the ECU had gone bad.

[Redline]

If all Else fails, consider replacing the ECU. I was chasing weird issues with the M3 wagon for a while and it ended up that the ECU had gone bad.

Hopefully not the case.

ive been thinking. Would a faulty Vanos solenoid cause this? It’s like timing keeps getting locked either retarded or advanced which is how it’s acting (pulls hard low and falls on its face, or falls on its face low and pulls hard up top) and also could be camshaft position at startup causing this stumble? But then again Vanos test passes and per Test plan it’s almost dead on perfect...I don’t get it. You’d think I’d be throwing some codes, I performed the besian fix where I cut it open and re-soldered all the contacts. Had an engine temp plausible code randomly show up last scan it hasn’t returned. (Both ect and thermostat new)

been a crap week, M3 still doing this, threads came out with the drain plug on the wife’s e91 (yay $1000 oil pan) and almost wrecked (And burned down) the e38 when the brake hose burst by the abs pump....I’m over bmw haha

[SteelGreyM]

Hopefully not the case.

ive been thinking. Would a faulty Vanos solenoid cause this? It’s like timing keeps getting locked either retarded or advanced which is how it’s acting (pulls hard low and falls on its face, or falls on its face low and pulls hard up top) and also could be camshaft position at startup causing this stumble? But then again Vanos test passes and per Test plan it’s almost dead on perfect...I don’t get it. You’d think I’d be throwing some codes, I performed the besian fix where I cut it open and re-soldered all the contacts. Had an engine temp plausible code randomly show up last scan it hasn’t returned. (Both ect and thermostat new)

been a crap week, M3 still doing this, threads came out with the drain plug on the wife’s e91 (yay $1000 oil pan) and almost wrecked (And burned down) the e38 when the brake hose burst by the abs pump....I’m over bmw haha

Perhaps your solder job wasn’t ideal? Maybe try out the Beisan solenoid. But I’m pretty sure you’d have a CEL for VANOS and timing codes. That’s what happened when my solenoid went out.

[M3Pat]

Redline other things to check out, fuel pump and fuel pump PWC (mistakenly known as fuel pump relay). The PWC module is located in the trunk on the passenger side wheel well. This controls the current/voltage to the fuel pump.

[Feffman]

Redline, this may sound too easy, but check the ground wire bolt is tight on the firewall just behind the brake fluid reservoir.

Feff

[Redline]

Ground cables good, clean and tight, all relays replaced previously. Scanned codes and have 3 instances of crank sensor signal (crank sensor is brand new genuine bmw) seems to throw that fault randomly. Checked the wires and they seem good....

also when it does act up Vanos is loud and engine is more clackity (can hear it rattling at 3krpms louder than normal inside the car) then when it’s acting fine smooth and quiet when driving no noise.

[SteelGreyM]

Ground cables good, clean and tight, all relays replaced previously. Scanned codes and have 3 instances of crank sensor signal (crank sensor is brand new genuine bmw) seems to throw that fault randomly. Checked the wires and they seem good....

also when it does act up Vanos is loud and engine is more clackity (can hear it rattling at 3krpms louder than normal inside the car) then when it’s acting fine smooth and quiet when driving no noise.

Do you hear this rattling only when the car is under load?(idk the proper way to say this)

as in if you push the clutch in and rev it do you hear the rattle at 3k? Or only when you are in gear and driving?

[Redline]

Do you hear this rattling only when the car is under load?(idk the proper way to say this)

as in if you push the clutch in and rev it do you hear the rattle at 3k? Or only when you are in gear and driving?

Can hear it with or without load, comes right from the Vanos unit. It’s not the head gasket rattle on light throttle.. not bearings..Rod bearings were done 20k ago. It’s a Vanos noise for sure as right off idle it has a bit of a rattle here and there if you lightly tap the gas in neutral (I was lazy and didn’t do the anti rattle kit, only seals, bolts, hub, Guides, solenoid repair and valve block cleaning)

it’s the typical Vanos rattle bmw even has a bulletin for loudest at 2800-3000 rpms the goes away above that and below.

just is louder when it’s acting up which is making me believe is possibly Vanos related?

drove it today and it was perfect lol, no rattle (well not louder than normal) yesterday was another story...

[Redline]

So going to try something. Going to remove the gas cap before starting it every time and see if the problem goes away. Would an evap system issue cause this? I mean it has the symptoms (hard to start, stumble, loss of power) but no codes. Thought about swapping the purge valve from my dads 03 M3 as well to see what happens. At this point I’ll try anything lol.

[Icecream]

The car won't start with the MAF unplugged.

It 100% will start unplugged. It will not however, start if the MAF completely fails. Happened to me on the road, car died, failed to start so I unplugged the MAF and luckily started right up, ran very well too lol.

[Icecream]

So going to try something. Going to remove the gas cap before starting it every time and see if the problem goes away. Would an evap system issue cause this? I mean it has the symptoms (hard to start, stumble, loss of power) but no codes. Thought about swapping the purge valve from my dads 03 M3 as well to see what happens. At this point I’ll try anything lol.

Just a couple things to consider. First off, if you are getting a consistent misfire on cylinder 4, that is where I would focus. A fuel problem at the pump, maf, o2 etc is unlikely to cause an issue on one cylinder. Try swapping coils/plugs on cylinder 4 with new ones (or another cylinder) and see if it goes away or follows that cylinder.
For good measure, check your battery cables are tight in the trunk. They shouldn't move or twist at all and the nuts can take a lot of torque. This has caused me grief on a couple occasions (unlikely to fix your issue but easy to check).
You had an O2 sensor code but it doesn't look like you changed the O2's unless I missed it. I would change them. Also which bank was the O2 sensor code on? If it is on the bank for cylinder 4 then you may have your culprit.

Also, as far as the gas cap issue. Not in my experience. I had a bad cap that gave me an SES light but no driveablility issues.
However, if you touched the fuel pump and installed something incorrectly, then yes, that would cause an issue. I think there is some kind of check valve in there that people mess up. I forget the details but it causes no starts on first attempts.

[Redline]

Just a couple things to consider. First off, if you are getting a consistent misfire on cylinder 4, that is where I would focus. A fuel problem at the pump, maf, o2 etc is unlikely to cause an issue on one cylinder. Try swapping coils/plugs on cylinder 4 with new ones (or another cylinder) and see if it goes away or follows that cylinder.
For good measure, check your battery cables are tight in the trunk. They shouldn't move or twist at all and the nuts can take a lot of torque. This has caused me grief on a couple occasions (unlikely to fix your issue but easy to check).
You had an O2 sensor code but it doesn't look like you changed the O2's unless I missed it. I would change them. Also which bank was the O2 sensor code on? If it is on the bank for cylinder 4 then you may have your culprit.

Also, as far as the gas cap issue. Not in my experience. I had a bad cap that gave me an SES light but no driveablility issues.
However, if you touched the fuel pump and installed something incorrectly, then yes, that would cause an issue. I think there is some kind of check valve in there that people mess up. I forget the details but it causes no starts on first attempts.

Head and gasket was well as pistons/rings are good leak down and compression are fine. Tested it twice now lol. Just replaced the a/f sensors and misfire is gone. Everything on this engine is new other than the idle control valve, throttle actuator, purge valve, and both camshaft position sensors. Everything else has been replaced...

my thought was it’s acting like a stuck open purge valve or clogged charcoal canister in a way. Gas cap is new but by removing the cap can help isolate the canister issue, swapping the purge valve with a known good one will isolate fuel vapor leaking into the manifold and can “flood” it out by being overly rich at startup or when running If the purge valve is sticking open. But at this point is a crap shoot lol. And it’s holding pressure, so not the fuel pump check valve (wish it was so I could be done with it)

only code I’m getting. Now is 10 [ 016 ] signal crankshaft sensor. Harness and connector are good, sensor is brand new genuine bmw....always throws this after the hard start and it’s in history not active. Idk. Tone ring on crank is good (had oil pan off not too long ago for the rod bearings)

[Redline]

So running active test on vanos inlet Vanos is stuck at 60° and inlet Vanos pilot control by DME is stuck at 51.20 and not changing with rpms or speed. Adaptation is .50. Exhaust side is 0° at idle and DME pilot is 0° as well. Exhaust Vanos changes with throttle and speed.

so is there an issue with the inlet Vanos or is it supposed to stay at 60° most of the time. Just weird that DME pilot control is lower than actual value.

[ATB88]

So running active test on vanos inlet Vanos is stuck at 60° and inlet Vanos pilot control by DME is stuck at 51.20 and not changing with rpms or speed. Adaptation is .50. Exhaust side is 0° at idle and DME pilot is 0° as well. Exhaust Vanos changes with throttle and speed.

so is there an issue with the inlet Vanos or is it supposed to stay at 60° most of the time. Just weird that DME pilot control is lower than actual value.

Let's just be crystal clear on nomenclature here: rather than the actual VANOS TEST function in DIS which tests response time and estimates leaking etc while at idle, you're referring to just monitoring the VANOS Actual vs VANOS Pilot DME values right? The numbers you're discussing are something that I've consistently seen on my car, and I've always wondered about. At idle I'm usually seeing "Inlet VANOS, Pilot Control by DME" (which is what the engine is commanding) at 51.20 whereas actual is sitting at about 60. Adaptation 0.90, so the adaptation itself is totally within spec but the pilot-actual value is not.

I've posted about this a few times on the old forums and nobody seemed to think it meant anything bad because the actual "VANOS Test" passes. HOWEVER: if you look at these values in DIS, it tells you right there on the page that if the VANOS has been adapted then the maximum allowable range between the pilot and actual value should only be +/- 2!! Whereas if adaptations have *not* been performed yet, then +/- 10 is allowable. See this photo:

'


I've always wondered if this points at an actual problem. Again, people just brush it under the rug saying "oh if it passed the VANOS test you're fine don't worry about it", but, again, this directly contradicts the information that DIS is giving about these values. So. Who knows?

Not sure how likely it is, but both of us have this weird 51.20 pilot DME value vs 60 actual on inlet, and we're both experiencing the same problem.

Anyone out there care to look at their inlet pilot vs actual values and report??