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Old Yesterday, 10:54 AM   #1
Registered User
Join Date: Jul 2010
Location: NC, USA
Posts: 309
My Ride: 2005 AW 330Ci ZHP
Exclamation Help / Advice with troubleshooting (Long-ish)

OK. I will start to keep this as concise as possible.
Although I have posted a bit about this in another thread, I didn't address the main story, nor was I very detailed.


2005 ZHP - 47k miles. No Mods except Dinan intake and SprintBooster. Sits a lot.

After a long period of sitting (we have been on vacay), on cold day car started and idled rough. Visible, palpable shaking.
Turned car off, started again: SES on, Started rough but settled into a smoother idle. RPMs steady and normal. But feels like its not the normal "sound/beat/pitch" of idling. No more shaking though.

Almost normal; slight feel of reduced power. SES still on. Idling still smooth.
Now when starting the car: Starts like normal "pitch", but after 2-3 seconds, drops to a lower pitch, but smooth. (but RPMs still normal).

Code checked at Adv Auto: P0302 : Cyl 2 misfire.

First suspicion: bad coil pack.

So, this is what I did:

-Got a basic code scanner; Scanned car again at home. (SES still on). Got same code as before : P0302
-Starting the car: still same symptoms; Starts like normal "pitch", but after 2-3 seconds, drops to a lower pitch (but RPMs still normal).
-ERASED the code, using the scanner.
-Swapped coil packs 2 and 3 (so now, suspected bad coil is on cyl 3), expecting / hoping a new SES will result with a Cyl 3 misfire code.
(Both coil packs looked similar in appearance to my newbie eyes; Spark plug wells also looked clean)

Started car again: Idled rough and shaky (just like when the SES came on before) for only a few seconds, but then settled to a smoother idle, and remained smooth. RPMs steady.
But.... NO new SES!
(in almost all troubleshooting threads I have read, people got the "new" SES shortly after swapping CPs)

Since then,
Car started like normal but "drops" the pitch / sound of idle. (The idle "changing" after immediate start feels like same change of sound that I listened to in a lot of YouTube videos: when a coil pack is unplugged.)
Driving: Same as before coil swap: Almost normal but not quite normal power.

This behavior remained for several days, and still no new SES. Have driven about 30-40 miles since then in different driving conditions.

Latest: Now the car starts like normal, and does NOT change the pitch / sound of idle. In other words, starts and idles like before any of this ever happened. BUT while driving I STILL feel like the car is not running on full power....
(still no SES and no stored codes)

So, I am baffled. I don't know why I never got a new SES after the CP swap. I think I have driven the car enough for it to come back.
Question: If I have to keep driving to get it back, then how bad is it to drive it in this condition? IDK if it's running on 5 cyl or what..

(sort of unrelated to Part 1)
While I was practicing pulling off coil packs (I found it hard), I pulled CP on Cyl 1 (remember this is NOT the cyl that misfired): -the boot remained on the plug and there was some wetness on the CP. Several people suggested that at least on THAT cylinder, there might be some leaking of the spark plug well gasket/seal.

Although this not related to cyl 2 misfire, I want some opinion of the following:
My local indie BMW shop is running a special on VANOS rebuild ( with anti rattle kit ) and VCG replacement - they're pretty good at what they do, and their special is not bad - they do this special annually, and use Beisan kit.

This would be the prefect opportunity for me to get the VCG and the spark plug well gaskets replaced and cleaned I think.
As far as VANOS, my car is by most standards too young at 47k miles
But I have heard people post or say that Vanos rebuild is beneficial even at a young mileage and sometimes I have heard a rattle noise but I have no idea is it's Vanos or not ...

What do you guys think ? Should I go ahead and get it done ?
And although it might be too early should I replace the plugs and / or the coil packs ? It would be easy for them to do as they have remove all that anyway to do the Vanos / VCG

Thanks for reading so far. What should be my next step?
-should I just wait and wait and drive the car while waiting for the SES to reappear?
-But is it bad to drive with this "reduced power"-feeling? Is it running on 5 cylinders? (Hope not)
-Should I get the whole thing (VCG/VANOS, CPs, SPs) done?

to diagnose if it's a CP, is it safe to unplug coils WHILE the engine is running?
2005 Alpine White 330Ci with ZHP
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Old Yesterday, 01:42 PM   #2
Registered User
Join Date: Jan 2013
Location: Socal
Posts: 5,145
My Ride: 328i, XC70
It's not uncommon for a coil to fail intermittently.
When a code is set next time, post freeze frame data, that will help with the diagnosis.

At 47K, your vanos seals should be fine.

GM No Reverse - posts 427, 439

E46 NO START - A list of possible causes

"You have the right to free speech,...just watch what you say!"
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