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Discussion Starter · #1 ·
I've got a 2003 D2 with 95,000 miles that I've owned for about 6 years. As long as I can remember I've had the occassional misfire at Idle conditions. I've replaced so many plugs and wires and coils over the years that I can't believe that these are the culprits.

Recently I had the dreaded coolant in the oil problem (which seemed to come from the front engine cover area) and I replaced quite a number of components. Since it was all apart I decided to replace the coils and wires again since they were so easily accessible. I was disappointed to find that my misfire at idle is still there. I have the HawkEye Scan tool and I've watched the Live Data show misfires on the Left bank on Cylinders 3,5 & 7, again when at idle. When I accelerate, the engine is silky smooth and I haven't experienced any misfiring (haven't heard it, felt it in the butt dyno, or seen it on the scan tool live data). There are no stored codes for any component that might give me a clue.

On rare occasion within the last month I will get an even numbered cylinder to show a misfire, but in the distant past I have had misfires on the even bank.

I dont know if this was coincidental, but once when I was at idle, with the scan tool plugged in watching the live data showing misfires, I turned on the climate control, which slightly raised the RPM's and the missing stopped.

As part of the recent overhaul I had the injectors sent out for testing and cleaning. All 4 Oxygen Sensors have been replaced before (about 10,000 miles ago), the Mass Air Flow Sensor was replaced 32,000 miles ago, the spark plugs were replaced this past summer and have hardly any miles on them, I just replaced both coils with Bosch Units and replaced the Ignition Wires with Magnecore 8.5mm wires.

If anyone has had a similar problem or has any insight I'd be glad to hear about it.

I started making a comprehensive list of what parts I've replaced over the years that might be related that I'll copy below here. Thanks in advance and Happy New Year.
-Manny

Fuel Injectors Cleaned: Dec 2014 @ 95,000 miles
RC Engineering
Injector 1, 5 & 7 "dripping"
Before After Cleaning
Injector # Flow (cc/min) Flow (cc/min)
1 178 (dripping) 190.0 (excellent)
2 185.0 (good) 191.0 (excellent)
3 181.0 (good) 190.0 (excellent)
4 179.0 (good) 190.0 (excellent)
5 147.0 (dripping) 189.0 (excellent)
6 184.0 (good) 191.0 (excellent)
7 168.0 (dripping) 189.0 (excellent)
8 180.0 (good) 190.0 (excellent)

Ignition Wires Replaced Dec 2014 @ 95,000 miles
Magnecore 8.5mm

Ignition Coils: Replaced Both Dec 2014 @ 95,000 miles
from RoversNorth : Bosch

Cylinder Head: Pressure Tested for cracks, Vaccum Tested for Valves - OK
Replace Intake and Exhaust Valve seals
Lap Valves

Block: Pressure Test for slipped liners - no leaks at liners found
Oil Pump Cogs looked good

Gaskets: Complete Engine Gasket Kit Replaced Dec 2014 @ 95,000 miles
-intake manifolds
- head gasket (no signs of failure in cylinders. only evidence of leakage was at both end water jacket:
failure was to the outside (i.e. external leak)
-Front Engine Cover/Oil Pump Cover - this appears to have been failure point. Gasket crumbling. Definite
evidence of leak at upper right (when facing engine from radiator), remainder of leak:internal
-Valve Covers (surprise surprise, they were leaking. Left Bank (as viewed from passenger compartment) seemed
leak onto front Oxygen Sensor harness and connector plug in the past

Water Pump: Replaced Dec 2014 @ 95,000 miles with OE Pump



Spark Plugs: Replaced all June 2014 (NGK BKR6 ES-11)

Oxygen Sensors: All 4 replaced 10,000 miles ago / 2 years ago (Dec2012 @85,000m) Recommended Replacement every 60k miles
Atlantic British MHK100920 + MHK100930 (not dealer part)


Secondary Air Injector Solenoid: replaced 15,000 miles ago (June 2012 @ 80,000 mi)

Crankshaft Sensor: replaced 22k miles ago. Atl. British ERR6898 (feb 2011 @ 73,000 m)

Heater Hoses & TStat: replaced all radiator/heater hoses with Thermostat (October 2010)

Mass Air Flow Meter: replaced 32,000 miles ago (Aug 2009 @ 62,000 miles) Dealer Warranty

Plugs & Wires: replaced crap OE with Magnecore 7mm wires at OE Champion plugs @ 63,000 miles - Sept 2009

Short Engine Replacement: replaced 35,000 miles ago (May 2009 @ 60,000 miles) Dealer Warranty
Slipped Liner @ Cylinder 4
brought in because oil pressure light comes on at start up and won't
disappear until accelerator is blipped


Intake Gaskets & Valve: replaced under extended Warranty with Dealer Parts Jan 2009 @ 58,000 miles
Cover Gaskets


Plugs & Wires: replaced with Dealer Parts (April 2008)
 

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Could this be a small vacuum leak somewhere? The fact that it smooths out at higher RPMs might be due to it building enough vacuum that isn't present at idle.
 

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There is a valve on the passenger side rocker cover that can get gummed up sometimes, when you took your motor apart did you clean that little sucker out with compressed air?
 

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Discussion Starter · #8 ·
There is a valve on the passenger side rocker cover that can get gummed up sometimes, when you took your motor apart did you clean that little sucker out with compressed air?
I'm not sure which valve you are referencing? Could you describe this valve or its location a bit more.

I'm guessing you don't mean the EGR valves that are part of the Secondary Air Injection System on those accordian like Y pipes, because those are on both passenger and drivers sides.
 

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Discussion Starter · #10 ·
Looking For Vacuum Leaks but so far No Joy

I sprayed Brake cleaner all about the various vacuum hose connections and the intake boot, near the MAF, Idle Control Valve, and Secondary Air Injection System, as well as the lines providing the Brake Booster with vacuum but I didnt get any increase in RPM's that I'd expect if those spots ingested the spray
 
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