S54 Crank no Start but I have (fuel, spark, and air)

[armenh7]

Turns out the issue was a loose TPS. What a rare case.

[BBRTuning]

Correct, Vanos pressure is NOT required for the engine to start up. I've measured this many times (for different reasons). As mentioned several times previously, if the engine sits long enough, you will have zero Vanos system pressure and it will take several seconds to build after starting. Sure, if you crank it long enough, you'll eventually build pressure too, but this isn't necessary for startup. In fact, you can start the engine right up with no oil in it at all if you like (wouldn't recommend!).

Adjusting this was a red herring, but either way glad OP "solved" it. Just want to make sure someone else that comes across this thread doesn't go down the wrong path.

[sapote]

How would you check while the engine is running if it doesn't start?

I don't think the vanos needs oil pressure for engine to start up. Last time when I worked on the vanos and after setting the timing -- both cams were at max retarded positions -- and at first crank it fired up and ran right away.
checking the pressure with engine running.

[sapote]

How would you check while the engine is running if it doesn't start?

I don't think the vanos needs oil pressure for engine to start up. Last time when I worked on the vanos and after setting the timing -- both cams were at max retarded positions -- and at first crank it fired up and ran right away.
checking the pressure with engine running.

[armenh7]

with engine running/idling.
If low, then adjust the P regulator nut -- turn it in/out to see P changes. If not improved then remove the vanos and check the oil pump disk and 4 small pistons for too loose to binding.

How would you check while the engine is running if it doesn't start?

[S54B32]

Here's your plot twist. And that's with the engine running so multiple times faster than cranking. VANOS just rebuilt and passes DIS test.

https://youtube.com/shorts/eMgm2MBT1tM

Sorry but what you expect from a couple of revolutions? Never say you see pressure instant....


I think you don't understand the point of this thread, or let's say maybe we talk not about the same.
it's not about normal operation and startup when all is fine(then your are 100% right, you will not "see" high pressure while 1-2sec of cranking), it's about that the engine not is not starting and cranking forever due possible no pressure in vanos.
So again, to know if that is your problem (no pressure in vanos prevents start of the engine), attach gauge and crank (yes, more than some seconds)! If no pressure builds up, than you have here a problem!

But yeah your are partially right. To build up minimal pressure you need to crank atleast 3-4 seconds or more depending how much oil is still in the lines/head etc. after complete vanos rebuild i had to crank at least 20+ seconds to see something. This is also the reason the vanos position is pre set for next start with the help of the accumulator during stop of the engine.

[Shonky]

Here's your plot twist. And that's with the engine running so multiple times faster than cranking. VANOS just rebuilt and passes DIS test.

https://youtube.com/shorts/eMgm2MBT1tM

[Shonky]

Sorry but that is simply wrong. Please don't spread info that you read somewhere. As soon as your turn over vanos pump will build up high pressure. Only that in normal operation the vanos splines are pre set to start, i doesn't meant the pump is not working and filling the accumulator until pressure regulation valve kicks in (it's mechanical connected, no way it can be disconnected during crank)


If you don't believe me, just pull the fuel pump fuse, attach a pressure gauge to the vanos and crank. Plot twist, you will be surprised...

I had this issue and OP also had this issue with vanos pressure setting. And this is exactly seen during cranking. Of course you set it later to correct value during idle, but to know if this is a issue you have to check during crank (because it's not starting).

No you are wrong I'm afraid. Even with the engine actually started it takes a good 5 or 10 seconds for VANOS to get to the full 100 bar pressure. There's no way it has pressure in the 1 or 2 seconds of cranking before the engine fires. Think about how many times the crank shaft even turns at a few hundred rpm for a couple of seconds. Not even close to enough time.

[S54B32]

You won't get VANOS oil pressure whilst cranking. As already noted VANOS is "set" at engine shut off for exactly that reason.

Sorry but that is simply wrong. Please don't spread info that you read somewhere. As soon as your turn over vanos pump will build up high pressure. Only that in normal operation the vanos splines are pre set to start, i doesn't meant the pump is not working and filling the accumulator until pressure regulation valve kicks in (it's mechanical connected, no way it can be disconnected during crank)


If you don't believe me, just pull the fuel pump fuse, attach a pressure gauge to the vanos and crank. Plot twist, you will be surprised...

I had this issue and OP also had this issue with vanos pressure setting. And this is exactly seen during cranking. Of course you set it later to correct value during idle, but to know if this is a issue you have to check during crank (because it's not starting).

[Shonky]

Exactly. Need to read the pressure during cranking.

also if pressure not going up with adjustment of the screw check if needle valve is hard damaged or maybe you missed parts during assembly like oil feed tube, vanos pump pistons or the little discs. Or if you have no rebuilded and just have this problem, both vanos pump tabs could be broken away.

You won't get VANOS oil pressure whilst cranking. As already noted VANOS is "set" at engine shut off for exactly that reason.

[S54B32]

with engine running/idling.
If low, then adjust the P regulator nut -- turn it in/out to see P changes. If not improved then remove the vanos and check the oil pump disk and 4 small pistons for too loose to binding.

Exactly. Need to read the pressure during cranking.

also if pressure not going up with adjustment of the screw check if needle valve is hard damaged or maybe you missed parts during assembly like oil feed tube, vanos pump pistons or the little discs. Or if you have no rebuilded and just have this problem, both vanos pump tabs could be broken away.

[sapote]

So do you check while cranking the engine? If it's reading low, what's the fix?

with engine running/idling.
If low, then adjust the P regulator nut -- turn it in/out to see P changes. If not improved then remove the vanos and check the oil pump disk and 4 small pistons for too loose to binding.

[armenh7]

You need a suitable pressure gauge with adapter (I have used one with scale from 50-200bar)

So do you check while cranking the engine? If it's reading low, what's the fix?

[S54B32]

How would you check this?

You need a suitable pressure gauge with adapter (I have used one with scale from 50-200bar)

[armenh7]

thank you very much. This was my culprit as well

How did you check this and what was the fix?