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Discussion Starter · #1 ·
Hi,

I've got a 2000 328Ci w/ auto trans. On cold starts w/ the car in PARK, the engine shakes. And when accelerating from a dead stop it studders.
I'm getting fault codes: 15/08 (Mass air flow sensor) and 15/EF misfire on cyl#2. The car has not stalled and the ambient temps have been 60F+ since the problem started.
I originally had thought it was the O-Rings on the double vanos which I had replaced about 75K miles ago.

I'm going to try cleaning the MAS w/ MAS cleaner and see if that fixes the problem. Has anyone experianced this problem before? If so, what was the solution?
Thanks for your help,
Frank
 

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Vacuum links are a likely culprit. I would also clear the codes and see what reappears. If still on cyl 2, the ign system is suspect. Age of plugs?
 

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Not sure I would jump on a MAF at this point.

Clear codes and see what code(s) pop back up first.

Suggest you swap #2 coil with a different coil and see if the problem follows the coil, they are known to fail. Also keep in mind lean mixtures require more Voltage to fire the plugs, so you may have a lean condition that aggravates a questionable coil, spark plug boot or spark plug
 

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Discussion Starter · #4 · (Edited)
Thanks for the quick replies guys.

Funny you should mention the vacuum system because I'm also getting a 15/92 fault code which is for the Evap capillary leak.
Plugs have 55-65K of use. I think they're NGK iridium plugs.

I cleared the fault codes, then sprayed the MAS with MAS cleaner and started the engine, waited for 30 seconds, and checked the OBDII. No faults. Drove the car for about 2-3 miles and the hesitation has been minimized but it's still there on acceleration during acceleration at or near a dead stop.

Parked the car and re-read for fault codes. This time 15/EF (misfire on cyl #2) was the only fault code. I'll see if can swap out the coils and check the condition of the plug tomorrow. It appears that it's the coil - but who knows...
 

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Discussion Starter · #5 ·
Well, I removed the coil from cyl #2 (fault code said it was bad) and switched it with the coil from cyl #1. There was a little bit of stuttering only when the engine was cold (air temp was 59F) but for the most part, the problem seems to have gone away. When accelerating from a dead stop the acceleration is smooth and I can feel a boost in power when going accelerating hard on the freeway.
I ran a fault check and received no fault codes at this time.
 

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Discussion Starter · #6 · (Edited)
Issue resolved

So, I first noticed the problem when the car would shake and shudder during startup and hesitate from a dead stop. No service engine soon (SES) light at this point.
I've come to realize that not all issues throw a SES light, so it's good idea to get a code reader and check it regularly. So I used a Peak code reader and found fault codes for the MAS and a misfire on cyl #2.
I cleaned the MAS with MAS cleaner and have not had another fault code for it - MAS issue resolved.

I swapped coils #1 and #2. Stuttering was greatly minimized but was still there. Peak reader showed no faults. So knowing things hadn't been entirely fixed, I replaced the NGX Laser plugs with new ones, and swapped coils #1 and #2 back to their original positions. The problem just got massively worse. The car was stuttering very violently at this point and it actually triggered the SES light. Peak reader showed 15/EF for misfire on cyl #2.

I then replaced coil #2 only (researched showed that most people believe changing only one coil instead of the entire set is fine) and the stuttering stopped, and there were no new fault codes :woot:

So that's my experience with fault code 15/EF. Thanks to everyone who replyied, and I hope this may be helpful to someone down the line.

Cheers
 
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