[belcom]

Before I started doing maintenance on the car it started fine but did have some initial hesitation, after maybe 5-15sec of rough idle it goes to normal and there is no idle problem when driving.

I did the following work on it:
1. Pulled the whole intake manifold and replaced CCV with brand new genuine BMW part, I took the hoses off very carefully and they're all fine. Did not break. Intake manifold did not have any excessive amount of oil inside, just a bit but my understanding its normal.

Note: Observation of the CCV operation before and after: when engine on, I opened oil cap and heard/felt some suction, but the engine didn't really do anything, just kept running the same. With new CCV installed, when I open the oil cap now there's almost no suction but as soon as its opened I can hear the engine idle changes a bit, I hear a kind of like suction noise around CCV area and its running a bit rough with cap open. When oil cap is closed it goes back to normal. I believe that is normal and how it should be. Correct me if I am wrong.

2. Cleaned out non-return valves (these were fairly clean to begin with, no sludge whatsoever)
3. Took out and disassembled VANOS solenoids, cleaned them out completely and put back together. No sludge. But when shaken, the movement is questionable.
4. New belt and belt tensioner (INA tensioner, same as genuine part)
5. New genuine air filter
6. Oil filter housing and oil cooler gaskets (elring)
7. Took out DISAs and checked with INPA. flaps were solid. Movement perfect. Then took them apart and replaced the flap, spindle, gear with metal parts by I6 Automotive, replaced the seal. When I opened these, there were no oil or sludge inside. all clean. I put them back together and tested with INPA again. They close and open same as before after rebuild.
8. Replaced spark plugs with NGK platinum specific model for N52 so I believe these were pre-gapped already. At the moment I put the old spark plugs back in for now but problem is the same so spark plugs don't cause the issue.
9. When taking things apart I also cleaned throttle body. It was pretty clean though, I did move the flap by hand for cleaning.
10. Intake manifold gaskets were also replaced

After first start up when everything was put back together I got a bunch of codes but then cleared them, it was quite rough in the beginning but then smoothed out.

Problem: Every time I start the car now cold or warm, I get really rough idle in the very beginning and most of the time if I don't give it a bit of throttle it just dies (like the original problem I had but amplified quite a bit).

And then I get VANOS inlet valve jammed code. So obviously I mucked something up when taking them apart. Then I ordered new VANOS solenoids, aftermarket by Standard Auto (made in Poland, originating from Germany) and put them in yesterday but the problem has not changed a bit. Still almost dies on start up but then runs perfectly while driving.

Help?

[E92William]

This is quite weird. So the only code you're getting is a jammed vanos one for the intake? If you have a scanner that can do live data it would be great to have a check at the fuel trims on start up. That rough idle could be a ton of things even a stuck injector leaking which is rare.
I wouldn't wanna go as far as taking off the cover to check the vanos actuators. Check if you don't do your own oil changes, that the oil filter cap has the basket inside that holds the filter with the little o rings and everything. This not being there can leak oil pressure down to the oil pan and cause vanos issues. I'd run an injector cleaner and give it an Italian tune up after clearing all codes then scan again.

[belcom]

Originally Posted by E92William

This is quite weird. So the only code you're getting is a jammed vanos one for the intake? If you have a scanner that can do live data it would be great to have a check at the fuel trims on start up. That rough idle could be a ton of things even a stuck injector leaking which is rare.
I wouldn't wanna go as far as taking off the cover to check the vanos actuators. Check if you don't do your own oil changes, that the oil filter cap has the basket inside that holds the filter with the little o rings and everything. This not being there can leak oil pressure down to the oil pan and cause vanos issues. I'd run an injector cleaner and give it an Italian tune up after clearing all codes then scan again.

Yes, right now only vanos inlet code. But it also shows as resolved in INPA. Before I replaced them code was there too but it was showing as unresolved.

I am sure I can set something up for live data. I have a bluetooth obd reader and also K+CAN cable that I use with INPA. But I would not know what to look for and where when analyzing the data.

Oil filter cap basket is there with both o-rings. I was surprised to find a made in china filter in there though Previous owner gave me an invoice of the last oil change from Sep 2019 so he did maybe a 1,000kms since then. I will replace oil soon with liquimoly and genuine filter.

[E92William]

If you have an obd Bluetooth scanner you can see live data with torque app. Short and long term fuel trim for both primary o2 sensors bank 1 and 2. I don't think this is the issue but could be. They should be close to 0.

Another thing that popped to mind is does the car crank long when starting? It could be a fuel pump that's not holding fuel line pressure overnight, or a battery that's not fully charged by the time you start. Would be worth checking fuel pressure, also next cold start leave the key in accessory position for like 15 seconds then try, that primes the pump. This issue could even be like a coolant temp sensor that doesn't sense the car is cold and doesn't tell the ecu.

[belcom]

Originally Posted by E92William

If you have an obd Bluetooth scanner you can see live data with torque app. Short and long term fuel trim for both primary o2 sensors bank 1 and 2. I don't think this is the issue but could be. They should be close to 0.

Another thing that popped to mind is does the car crank long when starting? It could be a fuel pump that's not holding fuel line pressure overnight, or a battery that's not fully charged by the time you start. Would be worth checking fuel pressure, also next cold start leave the key in accessory position for like 15 seconds then try, that primes the pump. This issue could even be like a coolant temp sensor that doesn't sense the car is cold and doesn't tell the ecu.

I will check fuel trim. No it doesn't crank long, starts right up. And actually I just charged the battery last week to 100%. Tested 15 second wait before start just now, nothing changes, starts, RPMs drop to about 1k as usual and then about 1-2 seconds later RPMs drop it shudders and shuts off. Don't know about the coolant sensor. Should it not show a code when a sensor fails?

Update: I reset Throttle body, VVT and VANOS adaptations to no avail. Actually it seemed to start fine when I reset VVT for exactly 2 times and on third attempt it started dying again. And then I came across a post where someone suggested to disconnect MAF sensor and run it without it. I did and behavior changed. With the MAF disconnected, the engine appears to be hunting (RPMs bouncing) but doesn't die and then eventually recovers and stabilizes. So it seems it is most likely something on the intake side of things. Maybe...

[E92William]

It's not uncommon at all for a bad MAF to not throw a fault code I've seen it a few times. See if you can get your hands on a good used one and try it out.
I'd think a bad coolant temp sensor would indeed throw a code.

[belcom]

Cleaned the MAF, but no change still. Used CRC MAF cleaner.

I just found the invoice from the last oil change and it seems they used 5w30 synthetic. Looking at the fact that they used an off brand china filter makes me question if the oil is of the proper origin or viscosity to begin with or whether its even synthetic.

VANOS depends on proper oil flow to work correctly is my understanding

[scanspeak]

I wonder if it's a battery issue in that after startup the voltage has dropped so much as to affect other electrical operations.

[E92William]

Yep^ that's why I wanted to check the battery voltage before starting it after sitting overnight and or check if it's weak. You can change the oil if you want. Won't hurt. That's the first thing I do on any car I buy used regardless of when they changed it.

I made a video on vanos and sorting issues with it on the N52 because of the personal problems I had with it.

What comes to mind to me now is that it only happens in cold starts, the VANOS system has these check valves that are filters on the side of the cyl head for the oil that flows into the actuators, these valves are meant to keep oil in the system from draining back into the sump after the engine is turned off, if one were to be malfunctioning it could be leaving the actuator that's tripping a code dry overnight and then it's fine after you start it up and run it for a few seconds as it gets oil. I think you should replace these with at least high quality new units and give it a try, very likely to be this.

[belcom]

Thank you for posting the video I had actually seen it before. Good explanation.

I took out the filter cap and oil filter. Here are the pics. The existing filter has ridges top and bottom, original BMW part right beside it does not look the same and visually looks bigger. Oil looks kind of dark (but I don't change oil regularly so not sure if that is normal for 1k after oil change). Basket is there. O-rings are there but perhaps the o-rings were not changed.

[E92William]

O rings don't look bad you could change them if you want and the filter, but I don't think this is the main issue unless those rings aren't sealing that drain back. I'm leaning more towards that non return valve staying open and draining oil out of the actuator overnight theory. Unless there was some wiring issue to the vanos solenoid on that side. Because there's only that code for this issue you're having.

[belcom]

Originally Posted by E92William

O rings don't look bad you could change them if you want and the filter, but I don't think this is the main issue unless those rings aren't sealing that drain back. I'm leaning more towards that non return valve staying open and draining oil out of the actuator overnight theory. Unless there was some wiring issue to the vanos solenoid on that side. Because there's only that code for this issue you're having.

I have taken those non-return valves out and cleaned them out. They looked fine though. Pretty clean.

I will be changing oil in a couple of days but want to try seafoaming injectors today/tomorrow morning maybe.

And I finally found my bluetooth adapter so I can check some data.



Update: I was troubleshooting further this weekend including an oil change. Nothing was helping, so I started going through everything I did and ended up looking at some vids of procedures I had performed. One of the simplest things other than spark plugs I did was replace vanos solenoids. Well in the video the guy had mentioned that if the electrical connectors are swapped between intake and exhaust car will not run right... I had immediately started having a light bulb moment. I hate to admit it but that was exactly it... It purs like a kitten now, starts right up, does not hesitate, idle is stable, pulls nicely and of course sounds soooo good! valvetrain is quieter too with fresh liquimoly oil and original bmw oil filter.

Also for anyone dealing with similar issue my codes were 2a82 which is jammed intake solenoid but every time I scanned it was there but showing as resolved. Also there was p0012 timing retarded code as well which was pending.

[mindhiest369]

i HAVE THE SAME PROBLEM. ON START UP IT RUNS ROUGH AND SOMETIMES DIES. WARM OR COLD START. ONCE DRIVING NO PROBLEM EVEN AT IDLE. i RECENTLEY HAD MY STARTER AND BATTERY REPLACED WHICH i KNOW THEY HAVE TO REMOVE THE INTAKE MANIFOLD. SO I THINK IT MAY HAVE TO DO WITH THE AIR INTAKE MABE THE MAF SENSOR. ANY IDEAS? ON A N52 ENGINE