Vanos Rebuild Start Hesitation

[jamesfoley]

Jumped in the car this morning and it threw a P0174 code, lean on bank 2.

Did some graphing of the MAF, RPM, and both banks Short fuel trim and noticed the RPM fluctuates slightly, with the short trims going positive and negative constantly while idle, and the MAF sits at 5 g/s or above. I'm assuming it's upset about the fuel mixture and is constantly trying to compensate with a wrong MAF reading?

Either way I should have a new MAF here tomorrow so will do some more captures when that's installed.

[ATB88]

I'm assuming genuine BMW is the only way to go with a MAF like every other sensor? They're just pretty expensive from the dealer 😅

Also, for the fuel system status of 8, should that be happening with the MAF removed?

The Bosch OEM sensor is the exact same, no need to pay for the BMW branded one. Same part.

[jamesfoley]

So it didn't help with hard start issue. But you need to swap the bad MAF as 5g/s at idle is wrong and I don't see what else can cause this.

I'm assuming genuine BMW is the only way to go with a MAF like every other sensor? They're just pretty expensive from the dealer 😅

Also, for the fuel system status of 8, should that be happening with the MAF removed?

[sapote]

Also worth noting that it still hard starts with the MAF unplugged. It's almost like nothing has changed other than I have the EML light on now.

So it didn't help with hard start issue. But you need to swap the bad MAF as 5g/s at idle is wrong and I don't see what else can cause this.

[jamesfoley]

Sorry to double post.

Just did another drive, this time I had a EML with codes for both MAF and temp sensor which makes sense. For these runs I reset the DME adaptations before I took the car out to see if it made any change to the fueling, but now my town drive log is littered with fuel status 8 readings.

https://datazap.me/u/jamesfoley/e46-m3-town-drive-no-maf-reset-adaptations?log=0&data=5-6

https://datazap.me/u/jamesfoley/e46-m3-warm-idle-no-maf-reset-adaptations?log=0&data=5-6

With the fuel adaptations reset the car basically drives exactly the same as it does with the MAF plugged in. I did get some bucking a couple of times though, not sure if thats normal, mainly from pulling away at junctions from standstill.

Also worth noting that it still hard starts with the MAF unplugged. It's almost like nothing has changed other than I have the EML light on now.

On a positive note VANOS test now passes without an issue, results here: https://i.imgur.com/wupfK6i.jpg

[jamesfoley]

Yes it's good idea, and this might help the hard start too.

So I have two new logs, both with the MAF removed, but doesn't look like it changed much other than make the car drive horribly. Worth noting that this didn't trigger a CEL or SES light, is that normal?

https://datazap.me/u/jamesfoley/e46-...f?log=0&data=5
https://datazap.me/u/jamesfoley/e46-...f?log=0&data=5

The town driving log still have a fuel status of 8 occasionally., and it didn't make a difference to fuel trims, unless that takes a couple of trips to change? I could reset the DME adaptations to clear those trims but not sure that would help

Unless the fact the fuel status still gives me 8's without the MAF point to the MAF being bad, honestly not sure how testing this works if I'm honest.

[sapote]

Could I pull the MAF and drive about and see if the fuel status 8's go away, or check the fuel trims?

Yes it's good idea, and this might help the hard start too.

[jamesfoley]

The data show these issues:
Fuel system status 8 happened many times during driving, it is bad. Status 2 or 4 is ok, but not 8 or 1. This indicates engine having fuel mixture issue. This is confirmed with rich fuel trim of around -10 total (LTFT + STFT).
MAF is around 5g/s at idle which is too high. I would try to swap with a known good working unit.
pre cat bank1 O2 seems a bit lazy old. The other 3 sensors are ok.

Why hard start? The DME cut down the fuel (negative 10 fuel trim) due to the rich mixture in the last drive. When starting, the DME used the last LTFT which was around -7 and this could cause lean mixture during starting and hard start or stall. So I think good or bad start is depending on the LTFT from the last drive before parked.

Could I pull the MAF and drive about and see if the fuel status 8's go away, or check the fuel trims?

[sapote]

Why hard start? The DME cut down the fuel (negative 10 fuel trim) due to the rich mixture in the last drive. When starting, the DME used the last LTFT which was around -7 and this could cause lean mixture during starting and hard start or stall. So I think good or bad start is depending on the LTFT from the last drive before parked.

[sapote]

Here are some Datazap links:

https://datazap.me/u/jamesfoley/e46-m3-town-driving?log=0&data=3-5-7-8

https://datazap.me/u/jamesfoley/e46-m3-warm-idle?log=0&data=3-5-7-8

https://datazap.me/u/jamesfoley/e46-m3-more-town-driving?log=0&data=3-5-7-8

The "More Town Driving" log does have a load of idle time at the start if thats of any use. Can always grab a longer log of needed.

The data show these issues:
Fuel system status 8 happened many times during driving, it is bad. Status 2 or 4 is ok, but not 8 or 1. This indicates engine having fuel mixture issue. This is confirmed with rich fuel trim of around -10 total (LTFT + STFT).
MAF is around 5g/s at idle which is too high. I would try to swap with a known good working unit.
pre cat bank1 O2 seems a bit lazy old. The other 3 sensors are ok.

[ATB88]

I have INPA working so I'd imagine Tool32 would work, though never used it. I'll see if I can get the results for that job though when I'm next tinkering. I want to re-run a VANOS test at some point too.




Thats fair, part number is 64111368684 right? RealOEM lists a "Corrugated metal tube" (12517508831) alongside it with I'm assuming the hose goes inside of? Did you replace this too?

I really dont think its timing anymore as its not consistent so no real reason to change the cam sensors yet, I did have a random crank sensor code which is the only reason that got replaced.

Yeah those PNs look right. Huh, so I did get the corrugated tube, which the vacuum tube does sit inside, it did not strike me as being metal though. Just black corrugated plastic. Picture looks right though. Anyway, the original vacuum tube itself on my car was clear and the replacement part was opaque black, but fit in and did its job just the same.

[jamesfoley]

Try to remove the camshaft sensors and hold the tip towards something metal. It should have a strong magnetic field. I experienced that some sensors from new* or old lose their magnetic strength by time or from (*3rd party) factory. Your engine will needs some time to rotate and cause enough magnetic field in the sensor to generate a good signal. I suspect that the exhaust one is for detecting the correct cylinder as that one has a missing slot in its trigger wheel. Just a thought, although it should be present all the time and not like you described.
Can you read ECU with Tool32? job, [status_geberrad_adaption] might tell us something.

I have INPA working so I'd imagine Tool32 would work, though never used it. I'll see if I can get the results for that job though when I'm next tinkering. I want to re-run a VANOS test at some point too.

I ordered them from FCPEuro, who sent me a fixed length. I can not remember if I ended up trimming down the length they sent me. I do remember it being fairly easy to route and decide on length. (and FWIW I did cam sensors. part of me is hoping our problem is the same and you're able to get to the bottom of it here, but the other part of me hopes your problem is different since mine feels unsolvable at this point . either way, pulling for you!)

Thats fair, part number is 64111368684 right? RealOEM lists a "Corrugated metal tube" (12517508831) alongside it with I'm assuming the hose goes inside of? Did you replace this too?

I really dont think its timing anymore as its not consistent so no real reason to change the cam sensors yet, I did have a random crank sensor code which is the only reason that got replaced.

[ATB88]

I don't suppose you know the length of the vacuum hose needed to go from the air rail to the fuel regulator do you? I've tried to pick this up but BMW want to sell it in metres. Same for the "Corrugated metal tube"

I ordered them from FCPEuro, who sent me a fixed length. I can not remember if I ended up trimming down the length they sent me. I do remember it being fairly easy to route and decide on length. (and FWIW I did cam sensors. part of me is hoping our problem is the same and you're able to get to the bottom of it here, but the other part of me hopes your problem is different since mine feels unsolvable at this point . either way, pulling for you!)

[Tomba]

Crank is new and OEM, not touched cam sensors though

Try to remove the camshaft sensors and hold the tip towards something metal. It should have a strong magnetic field. I experienced that some sensors from new* or old lose their magnetic strength by time or from (*3rd party) factory. Your engine will needs some time to rotate and cause enough magnetic field in the sensor to generate a good signal. I suspect that the exhaust one is for detecting the correct cylinder as that one has a missing slot in its trigger wheel. Just a thought, although it should be present all the time and not like you described.
Can you read ECU with Tool32? job, [status_geberrad_adaption] might tell us something.

[jamesfoley]

Crank and camshaft sensors new and OEM?

Crank is new and OEM, not touched cam sensors though