- Jun 30, 2012
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Buddy of mine has an '08 335i and just started getting a random 'half engine' light, which is apparently a 'reduced power output' thing. No DTC's stored. Says he felt slight random misfiring at idle. By the time I got there, it seemed normal, with MAYBE the odd random sputter. I'm talking about maybe 2-3 tiny hiccups a minute...no RPM change, nothing major at all...most people would not notice it.
He's convinced his 80k spark plugs are the culprit. I think he could be right. But I'm seeing some weirdness through datastream numbers, and I can't seem to get any good concrete info. We have both already experienced this pain with BMW's...the community is a combination of a) people who may know a bit about what they're doing, but they're talking about modded cars, and gathering additional info and making changes through aftermarket tuners, b) people whose cars are stock, but they have no clue what they're doing, and c) people who take it to the dealer (basically, group B, but they have the cash to burn).
So info I could probably get for an American or Japanese car seems to elude me when using search engines, looking through forums, ect. Factory documentation is probably the rarest of any car make...I wonder if their techs have to sign an NDA or something...
Anyway, what I saw at idle that concerned me: weird charge air temps (IAT reading), primarily. Like in the 150's (F, obviously) at idle on a hot engine. Ambient temp maybe in the 110's (normal for a hot engine bay in our climate). He thinks it's normal, and simply due to sensor location and engine heat. I am dubious.
Coolant temps normal. After shutdown and about an hour wait, coolant was down to 170 or so (a normal 185-200 or so when running, depending on if the cooling fan was kicked on or not), IAT still reading 140. Ambient temp down closer to 100.
Timing was in the negatives at idle. My theory is that the PCM is seeing the high charge air temp (but not out of range) and turning down the boost and backing off the timing to compensate.
It's had regular Mobil1 oil changes. Should have the latest in flaky HPFP revisions (parts replaced under the recall and/or extended warranty stuff).
Seems like we should have a few people here with experience with these engines. Any thoughts?
He's convinced his 80k spark plugs are the culprit. I think he could be right. But I'm seeing some weirdness through datastream numbers, and I can't seem to get any good concrete info. We have both already experienced this pain with BMW's...the community is a combination of a) people who may know a bit about what they're doing, but they're talking about modded cars, and gathering additional info and making changes through aftermarket tuners, b) people whose cars are stock, but they have no clue what they're doing, and c) people who take it to the dealer (basically, group B, but they have the cash to burn).
So info I could probably get for an American or Japanese car seems to elude me when using search engines, looking through forums, ect. Factory documentation is probably the rarest of any car make...I wonder if their techs have to sign an NDA or something...
Anyway, what I saw at idle that concerned me: weird charge air temps (IAT reading), primarily. Like in the 150's (F, obviously) at idle on a hot engine. Ambient temp maybe in the 110's (normal for a hot engine bay in our climate). He thinks it's normal, and simply due to sensor location and engine heat. I am dubious.
Coolant temps normal. After shutdown and about an hour wait, coolant was down to 170 or so (a normal 185-200 or so when running, depending on if the cooling fan was kicked on or not), IAT still reading 140. Ambient temp down closer to 100.
Timing was in the negatives at idle. My theory is that the PCM is seeing the high charge air temp (but not out of range) and turning down the boost and backing off the timing to compensate.
It's had regular Mobil1 oil changes. Should have the latest in flaky HPFP revisions (parts replaced under the recall and/or extended warranty stuff).
Seems like we should have a few people here with experience with these engines. Any thoughts?
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