Quote:
Originally Posted by DarkNemesis
Chinna. When did you replace your coils or spark plugs last?
I bought mine from eBay seller: germanautosupply
His coils were dated 12-11-15
The latest.
Plugs were best priced for a full set.
Not sure what regular idle should be on a n52, but seems slightly high.
Should be 600ish.
Could be wrong.
If your coils or plugs have never been changed, then that's where I would start. 95k miles is very high.
Check you coolant level.
Also, look on eBay for a BMW dealer selling these Solenoids for 109 each.
I replaced both of mine, but it didn't do much. Have had any solenoid errors at all ever?
Also, clean your injectors.
How?
eBay again look for BG 44k.
Buy 2 cans. Product number 208.
This should be written on each can.
I put 1 in 1 full tank.
Then when tank was nearly empty I put 1 more in the next tank. Just to be sure injectors got really clean.
Strongly recommend this.
Also download Bmwlogger.
Reset all you DME.
Follow the directions after DME resetting. The instruction on a sticky thread under coding section.
Keep in mind, it will not log, but you can reset dme adaptions.
95k mikes is a lot,
What oil are you using?
DN
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Thanks for detailed reply. Really appreciate that.
Spark plugs: Changed couple of weeks ago with NGK Laser iridium (same as OEM). One twist to that is, one of the plug is defective(cold start misfire). Old plugs are still in pretty good shape, so replaced that with old one, and now misfire is gone.
Coils: I have not changed any coils. But when I checked the coils, it seems some of coils are newer(inside the coil which connect to plug is different. Probably has been replaced previously. BMW folks says it is unusual for coils to cause rough idle(Except if it has misfire which can be detected).
Coolant: I just replaced thermostat because I have thermostat heater open circuit error. During this replacement, I drained coolant almost completely (2 gallons) and refilled with BMW coolant+distilled water. So coolant is not an issue.
Idle speed: Here are some changes from yesterday. After cleaning and swapping VANOS solenoid, the idle speed went up to 730. Never had any VANOS solenoids errors, not even in history. But by today evening it settle back to 660RPM again, back to original idle speed.
Like you said, It seems idle should be around 600ish. I felt now engine is somewhat smoother, but it may be simply placebo effect.
When compared to my friends 2006 325i, it is rougher.
Injector cleaning: I ran several bottles of fuel system cleaner, in this order sofar.(pretty much back to back).
1. 1 bottle of Techron Fuel injector cleaner
2. 1 bottle of Techron fuel system cleaner
3. 1 bottle of Techron Fuel injector cleaner
4. 1 bottle of Redline fuel system cleaner
But no change in rough idle. Now I got GAMUT with REGANE. I will try that tomorrow.
Meanwhile I also got MAF cleaner which I have not used yet. so MAF is next in line...
Also, please see the carbon on the pistons(via spark plug holes). Not sure if this is normal or not. How was yours when you changed sparkplugs?
Thanks