Maintenance:
Oil.
You may be tempted to and may read about using thicker oils, do not fall into this trap. The old M cars used thick oil such as 5W-50 as they had much looser clearances.
The modern N turbo engines (and M) use thinner oil, the clearances are much tighter and you will long term ruin your engine if you run an oil out of spec.
ALWAYS run the spec as per your car manual. Usually 5w-30 or 5w-40 LL04 /LL01. (ACEA C3, API SN).
Flow of oil is more important than thickness (and indeed, pressure) and if you were to run a 50 weight or above on your modern turbo BMW, when cold, there's insufficient lubrication of the big-end bearings.
Troubleshooting.
So you have 1 or more cylinder misfires what next?
Well first
0.5) if you have manual transmission, do you still have the dual mass flywheel? This will cause phantom misfires, you need to replace it with a single mass flywheel and uprate the clutch at the same time
1) Check age of spark plugs- and replace (make sure they're the right type) and gap (if NGK) Bosch can keep stock gap
2) Replace the coils
3) Sniff test for leaking injectors as per the guide (when refitting the injectors, ensure ALL have the decoupler ring fitted and fit NEW injector seals on the tip (Cheap from BMW). NOTE-this is nothing to do with if they leak fuel, this is a combustion seal only.) Inspect the injectors, there should be no evidence of black soot higher than the end (black) seal. If there is either that injector bore is ovalled or the seal was no good.
4) Check STFT- make sure bank 1 and 2 are tracking roughly even. Log backing off the throttle, do the Lambda AFR both hit lean relatively quickly? (234) Or does one lag behind. If one lags, that bank has 1 or more leaking injectors
a)Get them pressure tested by a specialist.
5) If the misfire persists compression test the engine, make sure little variance between cylinders*. Do a leakdown test.
6) If that comes back OK OR if the leakdown test shows excessive leakage in one or more cylinders, remove all 6 injectors again. Look at the injector bores.
They should be completely round.
If the car has been running with improperly or missing injector seals and or decouplers, eventually the seal will burn up and the bore will get burned and go oval.
The only solutions are a) bore fix- which are metal inserts to fix the bores or b) a new cylinder head.
* if one cylinder is massively down on pressure the car needs a rebuild. Most commonly this is caused by a cracked piston ringland. It is not visible with a boroscope.
Blowby.
As with the PCV setup, described below, block vacuum being correct is essential. If you have excessive blowby, a good test is to run the engine and open the oil cap. It should suck in, not puff out. If there's a cyclic puffing assume a cracked piston and do a compression test. Min 135PSI per cylinder, usually 160-180PSI with as little variation as possible (10-15PSI MAX). Dead cylinders are usually around 60PSI.
Leaking Injectors.
If I've directed you to checking your injectors for leaks due to readings from the logs, one of the easiest tests to do, which doesn't cost anything, is to run the car to warm, then park up engine off for an hour. Pull the plugs one by one and sniff them. Any that smell of petrol have the corresponding injector leaking. They should not smell (AT ALL) of fuel.
You can also reverse fit the hard pipe to the injector so it points up. disconnect power to all injectors and coils. Remove the injector and screw it to the upside down hard pipe. Put some paper underneath, and crank the car (it wont start). If ANY fuel leaks from the injector it should be replaced.
30BA/30BB
MSD80 suffer from weak MOSFETS and if you have the above code the MOSFETS need replacing, the parts are not expensive but it is a precision job. Contact me to be put in touch with someone who will resolve for you. MSD81 does not have this issue.
Coolant Temperature:
There are various cooling modes available in MHD to control the speed of the electric coolant pump.
For regular driving I recommend leave the car to regulate its own cooling temperature; for cruising and slower driving up to 110c is completely normal, as this is for best economy/wear, if the car detects sporty driving it will target a lower coolant temperature. You just need to be concerned if you get a yellow/red warning displayed as the coolant is out of range eg closer to 120c.
Modifications:
N54 specific:
(note all this is tried and tested and from actually seeing what works and what makes no difference)
When should I upgrade:
Charge Pipe: The stock charge pipe is fine to 30+PSI (really) if you want to run charge pipe meth you may wish to change to a metal charge pipe.
Downpipes*: Decat downpipes are a good idea when running more boost on any turbo setup.
Secondary cats: Not strictly necessary for removal and do not make any difference to power
3.5 Bar MAP sensor: Only if runnning 20+PSI ( resolution decreases the nearer the stock sensor gets to its 22 PSI limit.) (P/N 13628644433)
Walbro 450 Low Pressure Fuel Pump: Stock Turbos: Only if running high eth mixes, Uprated Turbos: running pump or ethanol (You should upgrade to a Walbro 450 whenever you uprate the turbos). It is NOT necessary for pump fuel on stock turbos.
Overdrive HPFP: If running or planning to run strong alcohol mixes, negates the need for PI (however be aware this adds load onto the timing chain, and therefore PI is preferable).
Port Injection: If planning to run strong alcohol mixes, PI can be fed from the LPFP to HPFP feed and controlled by a controller like the AIC split second or Reflex.
Stock Airbox: Fine to 500+BHP with drop in high flow filter, uprate if getting bigger turbos to dual cone (and run a filter for your single turbo, I do not recommend a turbo mesh as these do not filter anything, and at the dyno, the difference between an unfiltered single turbo to filtered is negligible).
DCI actually cause a drop in torque on stock turbos due to high IAT.
Intercooler: I recommend upgrading the stock intercooler as soon as possible to a 5" or ideally 7.5" stepped (which will require basic cutting to fit)- there are no downsides; by reducing intake air temperature, you maintain potential HP across the boost and rev range. There's a bigger volume of air to compress before it reaches the intake, but the lag introduced is negligible; if you are heatsoaked on the standard intercooler that will cause far more lag and power loss.
Injectors: Not required on this platform! The standard direct injection injectors are capable of injecting circa 6000cc which is more than enough for both pump fuel and alcohol fuels. It's more important to maintain rail pressure via overdriving the high pressure pump or supplementing with port injection.
As stock injectors are very expensive, when you get one that fails, it is fine to find a second hand e.g. from Ebay as long as that replacement is not leaking.
It is also possible to convert to port injection for regular running, deleting the DI entirely, using the NexSYS PI.
ECU/DME: Again - Not required on this platform! The MSDx ECUs (MSD80 MSD81) are incredibly capable for controlling both upgraded twin turbos and a big single turbo and utilising the latest MHD features can allow for map switching, port injection safety as well as all the other safety features that previously were only available with an aftermarket turning box.
The standard DME can be wired to a MAC solenoid to control an external gate for a single turbo.
Our highest horsepower car we have tuned (with a stock engine, stock ECU) made 757HP, as seen on Officially Gassed.
Coils: Not required, the standard coils are fine (Bosch pencil coils or Eldor), there's sufficient spark for high boost, even alcohol mixtures. If you're experiencing misfires, diagnose the misfires, rather than just throwing upgraded coils on. Dyno tested, makes no difference to HP. Additionally, makes no difference to timing corrections (coils sit above spark plugs, and have zero bearing upon pre ignition). (There are many upgraded coil options, all are OK, none are strictly necessary).
In terms of when should they be uprated, from testing, this is only when shooting for over 700HP as then you may get misfires with stock.
Sparkplugs: Two step colder plugs are necessary with uprated turbos, standard turbos work best with OEM Bosch plugs. With uprated turbos, be sure to run NGK 97506 gapped to 0.5MM OR (only with B58 coils and coil boots NGK 94201 stock gap -the sparkplugs with the smaller connector on the plug)
PCV: (as with turbo cars we have- P-ositive -C-rank -V-entilation not CCV)No need to change- lots of people mess around with the standard PCV flapper- this is totally not recommended; when off boost, the block needs to maintain correct vacuum of around 14inHG, if you change this, you risk both smokey idle and low rpm driving and also insufficient oil draining. When on boost, the PCV flapper opens and vents positive block pressure (blowby) out and either to atmosphere or to recirculate. Keep the OEM PCV flapper (at rear of valve cover).
On the low side you have a simple (OEM) check valve - on boost, to stop the valve cover being pressurised, and off boost, to open and allow vapours to go directly to head ports. You do not need to block head ports, you just need to ensure the low side valve is working properly. (they rarely fail). I have directly tuned many cars to beyond 30PSI on stock PCV with zero issues.
For your modifications including uprated twins, consider RDM performance parts- UK based, warranted, great value parts:
https://www.rdmperformance.co.uk/
For single turbo builds; forged engine builds, custom manifolds, parts fitting and servicing, drive in drive out with big single turbo, consider Deutschworks Ltd:
https://www.deutschworks.co.uk/
Fuelling/Power:
The biggest limitation to power is the octane rating of your fuel (it does not contain the chemical OCTANE, but is a rating about its knock resistance).
The higher the knock resistance, the more boost and timing you can run to make more power. (up to MBT).
The second biggest limitation is your block strength. Again you may have read stock n54 blocks taking 800HP. We don't recommend going over 550hp without forging.
Extreme Tuning:
By special arrangement we will tune beyond this recommended (non forged engine) limit, as with the OG car where it was tuned for 757HP on a stock engine but as with all tunes you must accept the additional risk this carries.
Dyno Readings:
Dyno readings vary massively, with mostly inflated US forums claims and do not reflect real life. Often the correction factor (CF) which if used properly means the dyno reads the same no matter the air pressure, elevation and temperature as well as transmission loss, is incorrectly adjusted or ignored completely in favour of the highest reading.
If you want to know if your local dyno is accurate, see what readings it gives for STOCK vehicles; they should be close to factory numbers. That means flywheel BHP, not flywheel BHP reading as WHP.
For accurate numbers try Mustang, Dyno Dynamics, Dyno Developments and if you're basing your expectations on other's numbers, be sure to check their CF (as it's not usually published).
Turbos/Boost and Power:
Bigger turbos equal more power AT THE SAME PSI. Hard to get your head around but more CFM equals more power.
At the end of the day, boost at inlet, is a measure of engine RESISTANCE, or lack of flow.
The more air that flows through your engine, the lower the boost and the more power.
The Torque/BHP argument -which is faster.
Well the first thing to say is they are not mutually exclusive. Break horsepower is a measure of usable torque.
So an engine that maintains torque across the rev range has more usable power (BHP) and is faster.
The pub talk about a diesel being quicker off the line- diesels make torque very low in the rev range, so "feel" faster when you push your foot down as they do not need to be revved very high for the engine to respond. They do not maintain the torque for very long in the rev range and therefore have less usable torque (HP). To the inexperienced driver this may make the car feel quicker, to the experienced petrol car owner, they know how to use the revs and power band.
*off-road/track only
