Changing plugs (N53 N54 N55)

Phil325i · 12-11-2015, 03:54 AM

A tip for those of you who do DIY servicing.

Been feeling my engine wasn't performing at its best for a while. But it was time to change spark plugs, so I thought all would be well. But the engine got worse! And started to misfire with a small drop in idle speed.

First suspected a duff plug, but finally found that the signal lead to the injector of cylinder 6 had become disconnected. For cylinders 1 to 5, these leads are bundled with other wiring and nicely secured in place on the valve cover. But the wire for injector six is one on its own and is unsecured, from the factory. And it passes very close to the coil (which has to be removed to change the plugs). So it's easy to get knocked.

So my tip is, when changing plugs, pay careful attention on cylinder 6 (the most inaccessible!) that you don't accidentally knock the injector lead off and give yourself unexpected rough running issues.

Oh and with the connector fully home, the engine now runs like a dream!

abeardo83 · 12-11-2015, 06:59 AM

love this type of stuff!

12-11-2015, 03:54 AM	#1
Phil325i Brigadier General 639 Rep 3,212 Posts Drives: E92 325i MSport Coupe Join Date: Apr 2012 Location: UK South East iTrader: (1) Garage List 2009 BMW 325i Coupe [6.00]	Changing plugs (N53 N54 N55) - a tip A tip for those of you who do DIY servicing. Been feeling my engine wasn't performing at its best for a while. But it was time to change spark plugs, so I thought all would be well. But the engine got worse! And started to misfire with a small drop in idle speed. First suspected a duff plug, but finally found that the signal lead to the injector of cylinder 6 had become disconnected. For cylinders 1 to 5, these leads are bundled with other wiring and nicely secured in place on the valve cover. But the wire for injector six is one on its own and is unsecured, from the factory. And it passes very close to the coil (which has to be removed to change the plugs). So it's easy to get knocked. So my tip is, when changing plugs, pay careful attention on cylinder 6 (the most inaccessible!) that you don't accidentally knock the injector lead off and give yourself unexpected rough running issues. Oh and with the connector fully home, the engine now runs like a dream! __________________ E92 pre-LCI 325i - Ohlins R&T; H&R spacers; M3 strut brace; Swift thrust sheets; 3 x chassis braces; diff brace; N53 V-brace; 034 subframe inserts; BMS clutch stop; BMS CDV; RE g/box mounts; Delrin shift bushes; Saikoumichi OCC; Cyba scoops; BMW Perf Exhaust; HEL s/steel brake hoses; M3 rear spoiler; Recaro Sportster CSs; M3 white dash LEDs; LED Angels; LED side repeaters; BMW Perf black grille; CSL reps; SSDD carbon diffuser; Monster Wrap black roof/clear front Last edited by Phil325i; 12-11-2015 at 07:10 AM..
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12-11-2015, 06:59 AM	#2
abeardo83 Captain 96 Rep 808 Posts Drives: E92 M3 Join Date: Nov 2015 Location: Cheshire iTrader: (2) Garage List 2008 BMW M3 [0.00]	love this type of stuff!
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