[willisodhiambo]

My 2010 N55 engine with 60k on the clock has black plugs all the time. Engine runs ok except for occasional minor stutters resulting from "superknocking" faults. These are so far in between that I stopped bothering with them but could be related.

Black plugs in my opinion mean rich burn, maybe oil burn too, though I do not top up oil more than 1/2litre in 10,000km so that rules our oil catch problems

I will be plugging in ISTA to look at a few things and would appreciate some advise what to go for. In my mind I am thinking to looking at performance of the following,

1. Precat O2 sensors
2. Injectors (though I don't see how all would behave the same and inject too much fuel, concurrently, consistently)
3. MAF (is there a recommended way to test the integrity of this)
4. Coolant temperature sensor or is that engine temperature sensor?(I notice that if car is driven normally, switch off and soon after restarted, it tends to cool harder than expected with temperatures hovering above 1/4 and half way. I thought it should be more constant near halfway.

Experienced members can chip in with advise, suggestions. I don't believe that an N55 can not have that nice ash brown burn I have seen in other BMW engines.

Thanks in advance.

[bryosb]

My 2012 97K, is also run dark all the time. I'm running ppk and change out my plugs every 30k. I post pics of my old plus in a bit. PM me a pic of your plugs if you got.

Your going to want to look at your multiplicative mixture adaptation. Any intake, exhaust leak will cause the computer to richen it up. Here in the shop we see at least one a week with some sort of leak.

Also check your barometric pressure, I'll attach a chart in a minute, N55 towards bottom of chart.

[bryosb]

You’re also going to want to keep an eye on this little bugger, the seal/flange for the valvetronic actuator. These $9 seals have a tendency to leak and cause major damage, the oil will wick into the valvetronic harness shorting out the DME, HPFP and CAS in worst case. As a shop that repairs DMEs we get these in all the time, got one in here right now, in fact that’s his picture I’m using.

Anyway just remove engine cover and lift up on inner cover and you can see if your is leaking, anyone with a N55 should take a peek!






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[nguyennhatquang]

If it black mean it too Rich..
did u read the Fuel Trim Data yet?

Rich condition can cause many reason...
DO u run any tune?

[willisodhiambo]

My 2012 97K, is also run dark all the time. I'm running ppk and change out my plugs every 30k. I post pics of my old plus in a bit. PM me a pic of your plugs if you got.

Your going to want to look at your multiplicative mixture adaptation. Any intake, exhaust leak will cause the computer to richen it up. Here in the shop we see at least one a week with some sort of leak.

Also check your barometric pressure, I'll attach a chart in a minute, N55 towards bottom of chart.

Here they are.l

---

My 2012 97K, is also run dark all the time. I'm running ppk and change out my plugs every 30k. I post pics of my old plus in a bit. PM me a pic of your plugs if you got.

Your going to want to look at your multiplicative mixture adaptation. Any intake, exhaust leak will cause the computer to richen it up. Here in the shop we see at least one a week with some sort of leak.

Also check your barometric pressure, I'll attach a chart in a minute, N55 towards bottom of chart.

By the way that is barometric pressure of what? Crankcase? N55 numbers look thoruoghly high compared to others.will run through as advised.


Here they are.l

---

You’re also going to want to keep an eye on this little bugger, the seal/flange for the valvetronic actuator. These $9 seals have a tendency to leak and cause major damage, the oil will wick into the valvetronic harness shorting out the DME, HPFP and CAS in worst case. As a shop that repairs DMEs we get these in all the time, got one in here right now, in fact that’s his picture I’m using.

Anyway just remove engine cover and lift up on inner cover and you can see if your is leaking, anyone with a N55 should take a peek!






Sent from my iPhone using Tapatalk

Marked for i
nspection

---

If it black mean it too Rich..
did u read the Fuel Trim Data yet?

Rich condition can cause many reason...
DO u run any tune?

Not yet, that will be part of my diagnosis scan. No tune.

[Node]

The quality of the photo is really bad. All gaps are in shadow but for me it seems like they may be a bit too big.

[willisodhiambo]

The quality of the photo is really bad. All gaps are in shadow but for me it seems like they may be a bit too big.

Yes, will try take better photos. The replacements were from the dealer so I did not re-gap, just checked that they were equal then threw them in!! If I recall they were circa 0.8mm but now that you mention it I will check them all.

[willisodhiambo]

The quality of the photo is really bad. All gaps are in shadow but for me it seems like they may be a bit too big.

Yes, will try take better photos. The replacements were from the dealer so I did not re-gap, just checked that they were equal then threw them in!! If I recall they were circa 0.8mm but now that you mention it I will check them all.

[nguyennhatquang]

If u can PM me...I can teamview & look for you If u want.

[willisodhiambo]

So I ran some tests. I have a feeling the car is running colder than it really should. When fan comes on it blows for a good minute or so until temperature falls close to 100degrees. I have never seen a cars temp oscillate this much.

Is this normal? I attach some readings and photo of the temp.