[srbarnes4ever]

Have had my E90 for 30k miles, just under 20k of which have been using the OTS Cobb AP Aggressive +FMIC. I don't have any obvious issues with detonation or misses so am wondering: 1)When should I change spark plugs and 2)I have seen talk of colder plugs and am wondering what the benefit is to considering them.

In addition to the above, the car has 95k miles total so is due for water pump, transmission fluid and a few other things soon.....gonna be an expensive next 12 months or so....

[DailyN54]

To answer your questions. You can do the plugs and coils as preventative maintenance or you can simply wait until you start having misfires and do it then. You can always take logs and see if there is any unusual timing being pulled. These cars will pull timing even in a stock car.

Colder plugs prevent pre-ignition and operate better in cars running higher boost levels.

Talk to your tuner about what gap they want you to run as well.

I wanted a reliable car so I went through and did all the maintenance on the car simply because I don't want to deal with it by surprise or end up stuck somewhere.

Good luck!

[TrollToll]

You'll get mixed reviews, but for your setup I would stick with OEM plugs. There are too many people reporting misfires with any single electrode plugs. They can and do work, but be prepared to play with the gap to get it working.

[Turkish Mafia]

I thought single electrode M4 spark plugs were pretty much plug and play for the N54. No issues with gapping etc.

There are more threads out there backing this up, but here is one sample:
http://www.1addicts.com/forums/showt...1185593&page=2

[Thxrick]

Plugs every 15-20k while moderately tuned (under 20 in boost). More often of tuned aggressively. At the point, you don't need one step colder plugs.

Coils are a good thing to do. You should't need to change them until you start throwing codes.

ZP trans. says change fluid and filter every 50-60k...

I have yet to change the water pump at 85k.

GL. FYI, I have a set of brand new Bosch plugs FS and will give you a good deal...LMK.

[AndyW]

Here is what I have in my basic maintenance tracker based on what i have learned on these forums (at 123k, had the car since 36K). YMMV.

Oil and Filter (6K)
Cabin air filter (30K)
Coolant Flush (50K)
Brake Flush (25K)
Power Steering Flush (drain and refill)(40K)
Spark plugs(30K)
Transmission Flush (full+pan replacement)(50K)
Coils (50K)
Clean air filter (K&E) (30K)
Ceratec Treatment (25K)
LiquiMoly Engine Flush (25K)
Walnut blasting(50K)

You are living on borrowed time with your water pump and thermostat. Just bite the bullet now and replace both and get a coolant flush out of it at the same time. Mine went at about 85K. I will replace again at 150K pre-emptively. 75K is nominal from what I have learned.

Other things to consider at 100K-125K:

VANOS solenoids
VANOS check valves
CAM Position sensors
Serpentine and pulleys
Replace all vacuum lines
Boost solenoids
MAP sensor and TMAP sensor
WB O2 sensors
Crank Position Sensor
Engine Mounts
Injectors (most expensive thing to do on this list)

All of these are home mechanic doable IMO and not ridiculously expensive.