2008 135i 117k Cold start woes

[germ]

It's been happening recently.

Left car for 3 days at airport parking. Come back today and terrible cold start. After that, no turbo power during 30 mi trip back to home (but no limp mode warning, either). Stop and restart car: run perfectly smooth, power is back.

Fault codes from Carly, all "Critical issues":

DSC codes:
- 005DE3 wheel speed sensor does not match configuration. Last occurred at 52k mi. I think I can safely reset this one
- 005DE1 Miscellaneous DSC causes. Last occurred at 10180 mi. I can reset this one

Engine codes:
- 0029CF misfiring cylinder 3. Last occurred at 117xxx mi. This is when I cold started
- 0029CE misfiring cylinder 2. Last occurred same mileage
- 0029CC misfiring several cylinders. Last occurred same mileage
- 002B2C high-pressure fuel, plausibility, cold start. Last occurred about 100 mi back
- 0029F3 fuel pressure sensor, electric. Last occurred about 5 mi before last cold start (?)
- two more "non serious" issues, back about 500 miles

Foot well module:
- 00A8C1: reversing light left defective. This is bogus. Works perfectly. I may have replaced the reverse light bulb with something non OEM

Instrument cluster:
- 009315 Gwsz error/left blink failure. This is bogus all blink lights work fine
- 00931B (severe issue) multiple possible failures related to outside temperature sensor. Works perfectly. I can reset this one
- two other non serious issues that I will reset

A few other non serious issues.


So it's obvious I have misfires.

Maintenance history:
- last oil change: 115k (Mobil 1)
- last spark plugs (due every 45k): 88k (Bosch equivalent)
- HPFP (under warranty): I think this was replaced once, early in the life of the car, but I can't find the record now
- turbos: replaced (under warranty) at 55k
- water pump: broke and replaced at 66k


What would you do?
- replace spark plugs (in theory not due until 135k)
- replace spark plug cables
- replace injectors?
- I hope it is not HPFP. I have somewhat long cranks at cold starts, but not too long (4-5s)
- I am curious about that fuel pressure sensor. Is that something that is easy to replace?

Any suggestions? I will search the forum as well.

[iminhell1]

I don't se mention of having the intake ports cleaned. That is where I would start.

[germ]

After a little research, it seems that misfires are a common issue for N54.

I will replace sparks and coils, which is a relatively easy and inexpensive fix.

The fuel pressure sensor is also inexpensive and more or less easy to replace depending on the car (haven't checked for the 135i). However, the failure mode of this sensor is to fully supply the pump at 100% duty cycle, so its failure shouldn't be causing too much trouble.

Cleaning the intake ports seems like a good idea at this point. I watched a couple of DIY videos and I concluded that I will leave this to a shop.

[Lester]

Vanos could need cleaning. Check on youtube for DIY. Also, use non-ethanol premium fuel if you can get it in your area.