[learjet23a]

A little history into this issue, I removed my valve cover to inspect my intake cam and bearing caps for unusual wear due to an unrelated p112f error. After reassembly the car started fine and ran drove for approx 30 min before the car went into limp mode / flashing check engine with rough idle and inevitably stalling. I pulled the codes and noticed random misfires on cylinders 4/5/6. Changing the coils to other plugs made no difference to the misfire code and the only way I could get the car to idle was to unplug the VVT connector. It started and ran normally almost the whole way home before it just suddenly stalled quietly. Since then the car just cranks with no start. Ista reveals no unusual error codes. I started to see some other posts here related to electrical issues causing the no start so I began to test for power to the DME. I started with investigating power to A4010 Junction box fuses F16,F37,F38 and F11 all see battery voltage 12V with ignition on. Valvetronic /Dme relay seem to operate correctly and F01-F03 fuses all have 12v. Wish I had some more codes to work with... Any help with steps to take would be appreciated.

I've attached some ista screenshot ignition on & during cranking.
video of start. https://www.youtube.com/shorts/1YeQTHqdnjk

[SlowE92]

Cylinders 4,5,6 all signal something wrong with that bank.. Did you unplug/break the 02 sensors when you removed the valve cover?

[learjet23a]

Yes I did unplug the o2 sensor plugs when I removed the valve cover

[fastboatster]

could have mixed O2 sensor connectors based on the codes

[learjet23a]

I don't think that's possible based on the connectors only fit one way, plus If I remember correctly I labelled the harness.

[SlowE92]

Originally Posted by learjet23a

I don't think that's possible based on the connectors only fit one way, plus If I remember correctly I labelled the harness.

What mods do you have done to the car? It says oxygen sensor emissions control not active, id double check your 02 sensor connections.

[learjet23a]

Okay, hopefully someone can chime in here because I'm kinda desperate! I did a compression check and to my shock I have zero compression in all cylinder except cylinder 4 which has 75psi. What the hell does that mean, can't be good.

[wheela]

Originally Posted by learjet23a

Okay, hopefully someone can chime in here because I'm kinda desperate! I did a compression check and to my shock I have zero compression in all cylinder except cylinder 4 which has 75psi. What the hell does that mean, can't be good.

How confident are you in your compression tester, or your method for checking? I've never done one personally, but it seems implausible that an engine would go from running to no compression by replacing the valve cover?

If compression turns out to be okay, I second comments that it seems like a bad connection somewhere from the valve cover job.

Can you share more detail about what made you suspect problems under the valve cover in the first place?

[SlowE92]

Originally Posted by learjet23a

Okay, hopefully someone can chime in here because I'm kinda desperate! I did a compression check and to my shock I have zero compression in all cylinder except cylinder 4 which has 75psi. What the hell does that mean, can't be good.

that usually means you did the compression test incorrectly lol. Theres no way you put a hole in 5 pistons simutaneously. Did you reset the timing?

[SlowE92]

Originally Posted by learjet23a

Okay, hopefully someone can chime in here because I'm kinda desperate! I did a compression check and to my shock I have zero compression in all cylinder except cylinder 4 which has 75psi. What the hell does that mean, can't be good.

Check your spark plugs, are they covered in fuel or oil?

[learjet23a]

Spark plugs are wet from fuel from continuous cranking yes. I'll try the compression test again but I did it twice and both times I recorded zero compression in all but cylinder 4 which was getting 75psi. Unless for some reason the cheap ass tester I bought is not making an adequate seal, I'll check the rubber o-ring. I did not make any changes to the timing. The valve cover removal was to check the intake camshaft I had replaced it months back due to scoring over lobes and bearing caps. I was checking for additional scoring of which there was none. Maybe I should pull the valve cover and inspect the timing chain maybe something broke..

[SlowE92]

Originally Posted by learjet23a

Spark plugs are wet from fuel from continuous cranking yes. I'll try the compression test again but I did it twice and both times I recorded zero compression in all but cylinder 4 which was getting 75psi. Unless for some reason the cheap ass tester I bought is not making an adequate seal, I'll check the rubber o-ring. I did not make any changes to the timing. The valve cover removal was to check the intake camshaft I had replaced it months back due to scoring over lobes and bearing caps. I was checking for additional scoring of which there was none. Maybe I should pull the valve cover and inspect the timing chain maybe something broke..

I just realized that your car is a manual lol, have you ever "money shifted" your car? If thats the case I'd check for bent valves.

[learjet23a]

No mis shifts at all, whats strange is I did get misfire codes and rough idle during the original incident and disconnecting the VVT connector smoothed everything to the point the car felt completely normal for at least 20min of driving before stalling out for good which has led me to this point. Just doesn't make a lot of sense to me how the car was driving fine stalled out of the blue and now no compression.... I'll open the valve cover tonight and see what I see I guess!..

[learjet23a]

Okay, update I have removed the valve cover and made some observations; manual rotating engine I see everything is moving both camshafts, crank pistons, intake and exhaust valves. There is good tension in the timing chain, only thing I found odd was the exhaust vanos seems a bit funky, like its not aligned correctly and the spring seems loose. I inspected the vanos bolts on both the intake and exhaust and they all seem to be correctly seated. I have ordered the timing kit but under initial observation at TDC the barcode on the exhaust cam seems correct however the intake cam is way off.

[SlowE92]

Originally Posted by learjet23a

Attachment 3291863

Attachment 3291864

Attachment 3291865

Attachment 3291866

Attachment 3291867Okay, update I have removed the valve cover and made some observations; manual rotating engine I see everything is moving both camshafts, crank pistons, intake and exhaust valves. There is good tension in the timing chain, only thing I found odd was the exhaust vanos seems a bit funky, like its not aligned correctly and the spring seems loose. I inspected the vanos bolts on both the intake and exhaust and they all seem to be correctly seated. I have ordered the timing kit but under initial observation at TDC the barcode on the exhaust cam seems correct however the intake cam is way off.

I'd cancel the timing chain kit order and just get new vanos solenoids.. I skimmed over the part where you said you removed the vvt connector and it ran fine.. but yeah seeing as how vanos controls camshafts that would definitely explain the 0 compression. It's weird you didn't throw any codes for it.

[SlowE92]

Originally Posted by learjet23a

Attachment 3291863

Attachment 3291864

Attachment 3291865

Attachment 3291866

Attachment 3291867Okay, update I have removed the valve cover and made some observations; manual rotating engine I see everything is moving both camshafts, crank pistons, intake and exhaust valves. There is good tension in the timing chain, only thing I found odd was the exhaust vanos seems a bit funky, like its not aligned correctly and the spring seems loose. I inspected the vanos bolts on both the intake and exhaust and they all seem to be correctly seated. I have ordered the timing kit but under initial observation at TDC the barcode on the exhaust cam seems correct however the intake cam is way off.

But my knowledge on this is very limited lol.. from what I understand you have to lock the crank at top dead center and rotate the cams until they align. Both the exhaust and intake have different depths when rotating. I'm sure theres a video that will guide you through it, luckily your cams didn't lock up on you though.

[learjet23a]

I didn't order timing chain, just the kit to set up the timing brackets and such. Yes things moving is nice question is if the intake cam is off did I make contact with any valves and cause internal damage. I have not checked the vanos solenoids, I;ll pull them out and take a look, I have replaced them within the year however. I'm familiar with setting up the timing as I had to do this entire procedure last year when I replaced the intake camshaft..

[SlowE92]

Originally Posted by learjet23a

I didn't order timing chain, just the kit to set up the timing brackets and such. Yes things moving is nice question is if the intake cam is off did I make contact with any valves and cause internal damage. I have not checked the vanos solenoids, I;ll pull them out and take a look, I have replaced them within the year however. I'm familiar with setting up the timing as I had to do this entire procedure last year when I replaced the intake camshaft..

If you have the intake manifold off you can check the valves from there and see if they're bent.. I doubt that you did however, it sounds like your timing is just way off and thats whats causing the 0 compression. Just make sure to set it tdc, and then remove the vanos.

[wheela]

Is it common for timing to be off if nothing is broken? It seems weird that exhaust cam is off, but intake cam isn't? I'm not to versed in the timing assemblies, so I'm not challenging, just curious to learn how this can happen.

Edit: I mixed it up, OP said exhaust cam is in, and intake cam is out.

[SlowE92]

I think when he unplugged the vvt connection (Vanos) and drove the car without it plugged in, it threw the timing off since the vanos controls the valves via cam phasing. It wont break anything mechanically since when the vanos is removed the cam moves to the default position. I think changing out the vanos solenoid will probably fix the p112f code, or MAF.

[wheela]

I believe vvt is the bmw acronym for valvetronic though, so unplugging the valvetronic motor shouldn't have any impact on vanos function?

But yeah, hopefully it's something simple with the vanos system making a cam appear to be out of time?

[SlowE92]

Originally Posted by wheela

I believe vvt is the bmw acronym for valvetronic though, so unplugging the valvetronic motor shouldn't have any impact on vanos function?

But yeah, hopefully it's something simple with the vanos system making a cam appear to be out of time?

VVT is also an acronym for Variable Valve Timing Solenoid, which is a fancier way of saying vanos. Don't know which one he was mentioning though i was just assuming.