[AndyVR]

My 320i N43 had been running perfectly & engine quiet, did a long drive at the weekend.

Monday night I got the 'Engine Fault - reduced power mode' warning on the dash, car felt ok initially, maybe a bit of vibration at idle, idle dipping very low sometimes, the warning would clear and then come back. No emission light or misfire codes.

Next day I got the same but I'm noticing loud engine noise at Idle & when pulling away - It sounds like a diesel, tapping/knocking! less noticeable when driving along but still there at all revs.

I checked the fault codes using INPA -

29F3 ? Low pressure fuel sensor ?
2D06 Air Mass system ? (MAF)
2E68 Knock sensor signal 1
2E69 Knock sensor signal 2
(+ some common Nox & lambda codes, but the car always runs ok with these)

I cleared the codes, ran the engine while stationary, the only one to come back was 29F3 , although the 'Reduced power' warning didn't come back on until I drove the car later. I need to read the codes again tonight.

I've had 29F3 the odd time in the last year or two with no issue, but never before that. The other codes are totally new.

Any thoughts on what's really happening here?
would engine tapping/knocking be caused by a faulty fuel low pressure sensor or MAF issue?
Should I discount the Knock sensor codes for now, it could just be reporting abnormal engine vibrations?

Do I order a Fuel low pressure sensor , and inspect and clean the MAF sensor first ?

Cheers for any advice.

[kofazz]

may i ask. what type of engine has ? n43 or n46 ? propably n43 right ? when u ll read the faults again update the data

[AndyVR]

Originally Posted by kofazz

may i ask. what type of engine has ? n43 or n46 ? propably n43 right ? when u ll read the faults again update the data

Good point, yes it's a 2.0 litre N43 engine

[kofazz]

n43 engine is really rear to have maf problems , would u be kind to delete the faults and inform here what are the reaming faults? it can be lots of things , knock sensor do be honest i ve seen 1 time in my life to be fault ( and i am 12 years bmw mechanic - diagnostisian ) delete the fault start it on idle and read the faults again. and update the faults, also do u have ista-d or only inpa to scan the faults?

[kofazz]

rare* not rear

[AndyVR]

Originally Posted by kofazz

n43 engine is really rear to have maf problems , would u be kind to delete the faults and inform here what are the reaming faults? it can be lots of things , knock sensor do be honest i ve seen 1 time in my life to be fault ( and i am 12 years bmw mechanic - diagnostisian ) delete the fault start it on idle and read the faults again. and update the faults, also do u have ista-d or only inpa to scan the faults?

it's good to have someone with your experience on here.

That's good to know about the MAF.

Unfortunately I didn't get chance to read the codes again last night, but will be doing later today.
I have Inpa, I can't remember if I have Ista or some version of it, will check later.

I will try and get a video of the engine noise too - it's a clear loud tapping or klacking sound, always consistent with the revs, when the revs are climbing or falling, at any temperature hot or cold.
I could be wrong, but it doesn't sound like the chain noise you get when the hydraulic tensioner is failing.

[kofazz]

Originally Posted by AndyVR

it's good to have someone with your experience on here.

That's good to know about the MAF.

Unfortunately I didn't get chance to read the codes again last night, but will be doing later today.
I have Inpa, I can't remember if I have Ista or some version of it, will check later.

I will try and get a video of the engine noise too - it's a clear loud tapping or klacking sound, always consistent with the revs, when the revs are climbing or falling, at any temperature hot or cold.
I could be wrong, but it doesn't sound like the chain noise you get when the hydraulic tensioner is failing.

ok my friend happy to help

[AndyVR]

When I checked the fault codes again with INPA after a day/a few miles drive I got the following-

29F3 Low pressure fuel sensor
2D06 Air Mass system
2E68 Knock sensor signal 1
2E69 Knock sensor signal 2


I cleared the codes again, kept INPA connected and revved the engine, the only code to come back was -

29F3 Low pressure fuel sensor (I would clear it, then it would come back quickly)



it wouldn't go into 'Engine Fault - reduced power' mode with the car stationary, being revved.


I cleared the codes, disconnected INPA and went for a drive, the engine responds normally despite the noise. Eventually the 'Engine fault' warning came up, so I stopped and reconnected INPA, and this time just got -

29F3 Low pressure fuel sensor
2E68 Knock sensor signal 1
2E69 Knock sensor signal 2



So it seems the Air mass fault happens later, and isn't causing the dash warning.

I have a theory, what do you think? I will try and upload a video of the engine sound.
I don't have ISTA-D.

[kofazz]

Originally Posted by AndyVR

When I checked the fault codes again with INPA after a day/a few miles drive I got the following-

29F3 Low pressure fuel sensor
2D06 Air Mass system
2E68 Knock sensor signal 1
2E69 Knock sensor signal 2


I cleared the codes again, kept INPA connected and revved the engine, the only code to come back was -

29F3 Low pressure fuel sensor (I would clear it, then it would come back quickly)



it wouldn't go into 'Engine Fault - reduced power' mode with the car stationary, being revved.


I cleared the codes, disconnected INPA and went for a drive, the engine responds normally despite the noise. Eventually the 'Engine fault' warning came up, so I stopped and reconnected INPA, and this time just got -

29F3 Low pressure fuel sensor
2E68 Knock sensor signal 1
2E69 Knock sensor signal 2



So it seems the Air mass fault happens later, and isn't causing the dash warning.

I have a theory, what do you think? I will try and upload a video of the engine sound.
I don't have ISTA-D.

to be honest having a fault to knock sensor is bizzare. 2 things first check if the dme ecu has any oil or water inside ( any type of corrosion ) open the box of dme remove the 2 ecu connectors and check if there any type of any liquid inside. 2nd check if u can below the intake there is a connector to both knock sensor, check the connection,maybe its not connected properly.if the knock sensors are not working it may do tons shits at how the engine is behaving

[AndyVR]

Originally Posted by kofazz

to be honest having a fault to knock sensor is bizzare. 2 things first check if the dme ecu has any oil or water inside ( any type of corrosion ) open the box of dme remove the 2 ecu connectors and check if there any type of any liquid inside. 2nd check if u can below the intake there is a connector to both knock sensor, check the connection,maybe its not connected properly.if the knock sensors are not working it may do tons shits at how the engine is behaving

Thanks, yes it is bizarre.

I did wonder about the connector to the knock sensors, if they share a connector that makes sense, I will check that connector.

Will also check the ECU/DME box - all the water covers are properly in place and water drainage is clear, I've never had an issue with water getting in there, but you never know.


The only other thing I considered, is that there is purely a mechanical fault, causing knocking/tapping on the head/engine block, that the knock sensors are hearing? Something like the High pressure fuel pump? or other mechanical issue.

I put the video of the engine noise on youtube, but the sound quality has been degraded so much, it sounds completely different! i will try another way.

[kofazz]

Originally Posted by AndyVR

Thanks, yes it is bizarre.

I did wonder about the connector to the knock sensors, if they share a connector that makes sense, I will check that connector.

Will also check the ECU/DME box - all the water covers are properly in place and water drainage is clear, I've never had an issue with water getting in there, but you never know.


The only other thing I considered, is that there is purely a mechanical fault, causing knocking/tapping on the head/engine block, that the knock sensors are hearing? Something like the High pressure fuel pump? or other mechanical issue.

I put the video of the engine noise on youtube, but the sound quality has been degraded so much, it sounds completely different! i will try another way.

if the knocks would hear any noise you wouldnt have fault like ( knock sensors signal) also n43 enines have an electrical water pump that means that there is an fuse that gives power ( voltage ) to the water pump <maybe the pump has a leakage inside that wiring ,so check the ecu and definetly check the knock sensors , like i am 70% that the sensors are not connected properly.

[AndyVR]

https://jumpshare.com/s/S5ffuaa1afp0bXAiL8TQ



Mp3 sound file of the engine noise/ tapping

[AndyVR]

Originally Posted by kofazz

if the knocks would hear any noise you wouldnt have fault like ( knock sensors signal) also n43 enines have an electrical water pump that means that there is an fuse that gives power ( voltage ) to the water pump <maybe the pump has a leakage inside that wiring ,so check the ecu and definetly check the knock sensors , like i am 70% that the sensors are not connected properly.

I replaced the electric water pump last year, I know the connector was good and dry then, but will check it again.

I had a quick look at the engine bay yesterday, I can see one of the knock sensors on the block under the inlet manifold, but the wiring and the other sensor are presumably further back, so would need to take the manifold off I think to check the wiring connector.

I had another listen to the engine, the tapping noise seems to be coming from the top of the engine, maybe more towards the exhaust side, I put my hands on the engine cover and inlet manifold with the revs at 2000 rpm, there was a vibration there that seemed a bit rough, not sure if that's normal or not.

The weather is bad here so will have to wait a few days to do futher checks.

[kofazz]

Originally Posted by AndyVR

I replaced the electric water pump last year, I know the connector was good and dry then, but will check it again.

I had a quick look at the engine bay yesterday, I can see one of the knock sensors on the block under the inlet manifold, but the wiring and the other sensor are presumably further back, so would need to take the manifold off I think to check the wiring connector.

I had another listen to the engine, the tapping noise seems to be coming from the top of the engine, maybe more towards the exhaust side, I put my hands on the engine cover and inlet manifold with the revs at 2000 rpm, there was a vibration there that seemed a bit rough, not sure if that's normal or not.

The weather is bad here so will have to wait a few days to do futher checks.

ok waiting for the results

[AndyVR]

Originally Posted by kofazz

ok waiting for the results

At the weekend I took the engine covers off to try and pinpoint the location of the top end engine noise (tapping) using a mechanic's stethoscope to probe different areas of the engine, with the engine held at about 3000rpm.
The high pressure fuel pump and the ends of the injectors gave off more noise than anywhere else (possibly because they are steel rather than ally), but they both sounded the same, so I couldn't say that the HPFP was an issue, or any injector.
I'm leaning towards it being cylinder head noise, as in hydraulic lifters or something else in the valve train. I've noticed it's very loud when the engine is cold, it's not quite as loud when warmed up, but it's still sounds wrong/bad and never goes away. A bit like a 1980's Ford Fiesta engine with noisy tappets, that you could hear coming a couple of streets away!

When the engine had been off for a while, I had a look at the timing chain through the oil filler - it had about 5-10mm of slack in it between the two camshaft gears - that doesn't seem right ? but when I ran the engine again and checked straight after, the chain was taught, so the hydraulic tensioner is working under oil pressure.

I did get into the ECU/DME box, it was bone dry, and the connectors all good.

For getting to the knock sensors & their connector, I think getting the inlet manifold off this model/engine is going to be tricky. There's a lot to disconnect and hardly any space. I couldn't see or reach the lower manifold bolt at the back of the engine, it's blocked by pipes & connectors and close to the bulkhead - so I didn't have time to start that.

I'm not sure where to go with this now - taking the manifold off will take up a lot of my time, and I know there's a mechanical noise issue at the top of the engine that is probably separate.
There's a thought - can knock sensors be damaged by excessive engine noise or vibration?

[kofazz]

Originally Posted by AndyVR

At the weekend I took the engine covers off to try and pinpoint the location of the top end engine noise (tapping) using a mechanic's stethoscope to probe different areas of the engine, with the engine held at about 3000rpm.
The high pressure fuel pump and the ends of the injectors gave off more noise than anywhere else (possibly because they are steel rather than ally), but they both sounded the same, so I couldn't say that the HPFP was an issue, or any injector.
I'm leaning towards it being cylinder head noise, as in hydraulic lifters or something else in the valve train. I've noticed it's very loud when the engine is cold, it's not quite as loud when warmed up, but it's still sounds wrong/bad and never goes away. A bit like a 1980's Ford Fiesta engine with noisy tappets, that you could hear coming a couple of streets away!

When the engine had been off for a while, I had a look at the timing chain through the oil filler - it had about 5-10mm of slack in it between the two camshaft gears - that doesn't seem right ? but when I ran the engine again and checked straight after, the chain was taught, so the hydraulic tensioner is working under oil pressure.

I did get into the ECU/DME box, it was bone dry, and the connectors all good.

For getting to the knock sensors & their connector, I think getting the inlet manifold off this model/engine is going to be tricky. There's a lot to disconnect and hardly any space. I couldn't see or reach the lower manifold bolt at the back of the engine, it's blocked by pipes & connectors and close to the bulkhead - so I didn't have time to start that.

I'm not sure where to go with this now - taking the manifold off will take up a lot of my time, and I know there's a mechanical noise issue at the top of the engine that is probably separate.
There's a thought - can knock sensors be damaged by excessive engine noise or vibration?

i dont think the knosck sensors got damaged from the vibrations, also the hppf and the injectors in an a direct injection system (gasolin) always makes click noises. the chain should be tight at all moments maybe the chain got streched a little bit.now i can check and tell you want you need to remove the intake manifold . but i am sure there are plenty youtube videos that show you the way .

[AndyVR]

Originally Posted by kofazz

i dont think the knosck sensors got damaged from the vibrations, also the hppf and the injectors in an a direct injection system (gasolin) always makes click noises. the chain should be tight at all moments maybe the chain got streched a little bit.now i can check and tell you want you need to remove the intake manifold . but i am sure there are plenty youtube videos that show you the way .

Yeah I'm familiar with the usual clicking noises from hpfp & injectors and other things on this engine, but this noise was very loud abnormal tapping.

Something very weird happened on Wednesday, I drove the car home from work as normal (7 mile drive) , I realised there had been no dashboard warnings or faults.
When I got home I noticed that the engine tapping had completely disappeared! the engine is quiet again and running perfectly!

After 3 weeks of continuous engine tapping, it has suddenly fixed itself!

It is still running quietly, it has not come back. I'm thinking it could of been a stuck hydraulic lifter, or something else stuck in the valvetrain?

I took the opportunity yesterday to do an oil & filter change, as it's almost a year /6000 miles since it was last done.

It's still running quietly and I have taken it for a good blast to get it hot.
Most of my journeys are 3-7 mile commutes at slowish pace.

On a seperate note, I've ordered a new Hydraulic timing chain tensioner, to see if that helps with the slightly slack chain when the engine has been off for a while - I'm sure they have a spring inside them to maintain chain tension when the engine is off, maybe it's broken.