N52 cam/crank synchronisation error

[BenM]

It seems I have a problem with my Coupe. I was getting an EML which was giving 002A9A - inlet cam sensor fault. The car was driving fine and since it was due for MOT shortly I bought a new sensor with the intention of getting the garage to fit it. A few days later I pulled into a petrol station, filled up, and then the car wouldn't start. I was now getting bot sensor faults - 002A9A and 002A9B - intake and exhaust sensor faults. I got the car recovered to my local garage, who are talking about potential timing chain issues. They have managed to get the car started from cold and it runs, but not smoothly. They want to take it apart and check the chain and tensioners, and make sure it hasn't skipped a tooth - I have suggested that before they do that they replace the intake sensor (since there's a new one sat there), check the cam sensor wiring and then take out the Vanos solenoids and clean them before looking at the timing.

So - anyone have any experience in getting both intake and exhaust cam synch faults? Logic would suggest the timing could be a problem - or it could be the crank sensor - but I've also read that sticky solenoids can cause the issue? The car has only done 55k miles so I would doubt stretched chains, it gets an oil change every year but is a bit of a garage queen and probably only does ~1000 miles a year. It was running like a new engine before this issue.

 

[enuff_zed]

To me, logic would say you can't have had only inlet first, then exhaust later if the timing had jumped a tooth. Surely it would have affected both at the same time?

 

[BenM]

To be clear, it was intake first, and then intake and exhaust together - so I think jumping a tooth could be possible, but a different fault than the original intake-only error.
Is it feasible that sticky vanos solenoids might cause a sync error on both sides?

 

[enuff_zed]

To be clear, it was intake first, and then intake and exhaust together - so I think jumping a tooth could be possible, but a different fault than the original intake-only error.
Is it feasible that sticky vanos solenoids might cause a sync error on both sides?

Well it's so simple to take them out and clean them I think it's a no-brainer to at least try that first.

 

[BenM]

That's what I've asked them to do, even before the replacing the cam sensors.
Next question - the cam sensor bolts are in VERY tight and they're worried about them snapping. Any tips for getting them loosened off, other than application of heat?

 

[Motionblurrr]

IIRC, those engines are rare (and M54B30s) to jump timing like that. They're pretty robust. How many miles on your car?

A failing inlet sensor would definitely make your car run rough or very rough. Cleaning won't do much to a sensor but temporarily limp it by a bit longer. If you got a code for the inlet sensor that means it's on it's way completely out.

 

[j3nks79]

IIRC, those engines are rare (and M54B30s) to jump timing like that. They're pretty robust. How many miles on your car?

A failing inlet sensor would definitely make your car run rough or very rough. Cleaning won't do much to a sensor but temporarily limp it by a bit longer. If you got a code for the inlet sensor that means it's on its way completely out.

It’s an N52 engine.

I’ve seen a handful now of timing being a tooth out.
Usual after a AUX belt has let go and got wrapped around the crank.
Also cars with long intervals between servicing causing the tensioners to slacken and allow a tooth jump.

But obviously the easiest thing to start with would be cam sensors and crank sensor.

Then solenoids and check valves.

After the would be taking off camcover locking cams and pinning crank to see if it’s times correctly.
That will tell you straight away if it’s skipped a tooth or not.

 

[Motionblurrr]

It’s an N52 engine.

I’ve seen a handful now of timing being a tooth out.
Usual after a AUX belt has let go and got wrapped around the crank.
Also cars with long intervals between servicing causing the tensioners to slacken and allow a tooth jump.

But obviously the easiest thing to start with would be cam sensors and crank sensor.

Then solenoids and check valves.

After the would be taking off camcover locking cams and pinning crank to see if it’s times correctly.
That will tell you straight away if it’s skipped a tooth or not.

Damn, I stand corrected lol. I don't mean to hijack the thread but are M54B30s also easily susceptible to this as well?

 

[j3nks79]

It’s an N52 engine.

I’ve seen a handful now of timing being a tooth out.
Usual after a AUX belt has let go and got wrapped around the crank.
Also cars with long intervals between servicing causing the tensioners to slacken and allow a tooth jump.

But obviously the easiest thing to start with would be cam sensors and crank sensor.

Then solenoids and check valves.

After the would be taking off camcover locking cams and pinning crank to see if it’s times correctly.
That will tell you straight away if it’s skipped a tooth or not.

Damn, I stand corrected lol. I don't mean to hijack the thread but are M54B30s also easily susceptible to this as well?

Not sure tbh mate

 

[BenM]

Thanks for all the replies so far. I spoke to the garage this afternoon, they are 99% sure it's not a timing issue (as I told them it probably shouldn't be on a low mileage N52). Tomorrow they're going to try to get the cam sensor replaced, hopefully without breaking the bolts, then if that doesn't sort it vanos solenoids and check valve cleaning. With luck that'll sort it.

 

[BenM]

Just to close this one out - seems like it was both cam sensors at fault, having replaced them both the car is now driving perfectly again. Bit weird that they both failed at more or less the same time, but here we are. I'll probably clean the solenoids and the check valves for good measure at some point.

 

[Motionblurrr]

Just to close this one out - seems like it was both cam sensors at fault, having replaced them both the car is now driving perfectly again. Bit weird that they both failed at more or less the same time, but here we are. I'll probably clean the solenoids and the check valves for good measure at some point.

Nice! I had a feeling it wasn't timing. These cars' engines are very robust (minus cooling system and vacuum leaks) so it had to be the sensors. Sometimes they do fail like that near each other but be glad you got both sorted at once instead of the other sensor going bad a few months down the line.

It's quite alarming how badly the car runs when the sensor goes out.

 

[Mr Tidy]

That's good news Ben.

N52 engines are pretty robust (I'm on my 4th) so a jumped tooth on the chain did seem unlikely.