2012 N16 R56 Won't Start Up After Rebuild
 

I bought a poorly cared for, 2012 Mini Cooper Base (N16 Engine). Automatic transmission. It only has 48k miles, but was basically ran into the ground. Oil and coolant basically everywhereI replaced every gasket you can think of, had the cylinder head cleaned and machined. Valve seals replaced and valves tested and also the below:

• New Head Gasket
• New Thermostat + Housing
• 4 new pistons, including rings
• New timing chain
• new belt
• New valve cover
• New plugs and coils
• All single use bolts were replaced with new, everything torqued to spec.

Obviously full of oil and coolant now. All put back together. Cranks just fine, but never starts up. Confirmed the spark plugs are firing, fuel is getting to the chamber, and the throttle body is working as expected. Low compression on cylinders 2 and 3, BUT they both passed a leak down test with flying colors. Not sure how that works. You’d think it’s a timing issue, right?

Timing has been checked and verified probably 10x now. Cams and crankshaft are all properly aligned. The engine won’t even start up when using ether (starting fluid). All connectors are properly connected, all adaptations have been reset and the valvetronic motor has been “taught”. Me and a few other mechanically inclined people, including 1 other MINI specific buff (super knowledgeable) can’t figure out why it won’t fire - especially with ether.

There are only two permanent engine codes (can only be cleared after so many key cycles) from before I rebuilt it: P0128 and P0328. There are no other engine codes and I couldn’t find any blown or bad fuses. All engine grounds are connected properly.

Short of trying to find a random and unknown short (that’s also not producing a code) - any ideas on what the issue could be? Been troubleshooting it for days and can’t figure it out.

Low compression in two cylinders is the white elephant in the room.

Define “low compression”? Does it “want” to start, and just doesn’t catch, or will it not fire at all? Even with crappy compression in just two cylinders, it should want to catch if you are getting fuel and spark.

@Heine03 ,

Double check the “CAM & CRANKSHAFT sensor. These sensors can go

@njaremka Sorry for the delayed reply! Been a busy last two days. It does. You can feel/hear it firing a little in (I assume) the two normal compression cylinders. It certainly tries! My compression test was as follows -> 95, 30 ish, 30 ish, 120. Keep in mind though this is a cold engine, with likely little oil worked into the piston bores since the pistons and rings were all replaced.


@Vanski Sorry for the delayed reply! Been a busy last two days. This is 3 separate sensors, correct? 2 Cam sensors on the Valve Cover, and a Crankshaft sensor somewhere on the block? Is there an easy way to test these? And if they had failed, would they not throw a CEL? Please let me know!

Add some engine oil to the two low compression cylinders. Then recheck the cylinder compression numbers. If better, check whether engine will start.

@Heine03 ,

So, the thing about low compression. The motor can still run, but not smoothly. Your complaint is the motor won’t even run at all. All it does it cranks but does not run.

as for the cam sensor, your N16 motor has 2 cam sensor, one on the intake and the other on the exhaust of the camshaft. The way to check these sensors is to use the ohm meter to see if there are any resistance. Wave a small piece of magnet over the sensor to see if you get any readings on the ohm meter.

Worst case scenario would be the DME heading out to lunch if your three sensors are good.

@Vanski - Do you have any info on the how to properly test the cam sensors? I verified voltage from the battery/ECM is good - but after disconnecting the sensors I cannot get any resistance readings on them. Should I be able to measure resistance? I tried putting them near a magnet as you suggested, and still couldn't get a reading.

I can't find anything online about testing them for resistance though, so maybe I am doing something wrong? Also, is it possible to have bad cam sensors without an engine code?

Thanks for your help guys. I am an idiot, and did my leak down test with a compression testers hose.... I did a proper leak down test and confirmed that my exhaust valves are leaking. So I should be all set!

Engine properly timed? Piston/valve collision?

@Heine03 ,
did you use the camshaft locking tool when you put the timing chain back on? As @Maybe, maybe not has suggested. Mini Cooper engines are interference motors so timing is everything and imperative(no if’s and’s or but’s about it)

Eric forgot to torque the crankshaft bolt to spec after replacing the timing chain. He bent the two exhaust valves in cylinder 3.

Cylinder head "cleaned and machined." Need the details on the cylinder head repair ... what exactly was done by the machine shop? N series engines have problems with valve seats dropping and burned exhaust valves. Whenever you pull an N series engine cylinder head, get all the valve seats replaced with the deeper SBI valve seats! Factory valve seats are only .22" deep; consequently, they tend to fall out especially after grinding; they also tend to drop when the engine is overheated.

Also, replace all the valves, you can't grind these valves because you won't have enough margin left. I also recommend an ARP head stud kit.

Have you checked your 5v reference circuit? You'll need a lab scope to check cam/crank correlation. That will also tell you if your sensors are working properly.