[mcsweeto]

I haven't had time to do any proper pulls or logging, but wanted to fish around for some opinions here to put my mind around it.

I had an errand to run on my way into work this morning and when I started my car up and sat for a bit to send an email, I couldn't to help but notice an new pattern to my engine's idle I hadn't noticed. Before I stopped to run the errand, my engine had come fully to temp and drove fine, as usual. When finished with the errand, I sat in the car for a bit, engine off with radio and accessories on (maybe a half hour) and was alerted to the battery having discharged. I started it up as I did need to get to work, it was a bit slow to do so. The engine had cooled of a bit as it was in the low-40s, but that's when I noticed the idle pattern. Here's a short log at idle before I pulled off:

https://datazap.me/u/mcsweeto/pulsin...22-23-24-25-26

The RPMs were noticeably pulsing. It stuttered a bit and felt a little underpowered pulling of. Maybe this had something to do with the battery drain, but here I am.

[exE36M3]

Or maybe it's time for an intake walnut blast?

I was asking about this with a local indy shop. The F3X series doesn't have idle issues like the E9X did, but they did mention that some F3X come in with intakes coated in dirt at like 50k miles and some still clean at 100k+ miles. (As an aside when I had my Miata supercharged, I noticed a TON of dust in the intake tract when I ran a K&N oiled filter.)

Either way, with direct injection cars, dust and dirt accumulate in the intake track which may affect idle.

[mcsweeto]

Originally Posted by exE36M3

Or maybe it's time for an intake walnut blast?
I noticed a TON of dust in the intake tract when I ran a K&N oiled filter.

Or maybe start washing things down with a WMI kit. I'm due for a VC/VCG replacement. I'll have a look at the ports and see how bad the build up is.

I'm starting to think the battery drain was contributing somehow. After it came to temp again it felt fine, as it did later in the day on the drive home.

[harkes]

Mine start doing what sound similar consistently after ~10 cold starts after a re-flash. Rough idle in open-loop as the cat pre-heating cycle is supposed to take place. However, car is not doing any pre-heating as I have the "I like to speak to my neighbours again" option enabled.

[harkes]

.............

Tried to explain the problem to both MHD and Fabian several times, but I guess they have more important stuff to do

[harkes]

My bad - should have checked the log first Def not the same problem. -8.6psi at idle......WHAT?? Try throw a new MAP sensor at it.

[mcsweeto]

Originally Posted by harkes

However, car is not doing any pre-heating as I have the "I like to speak to my neighbours again" option enabled.

I'm glad it's warmer out now, somewhat. I had been in preheating mode, or as I like to call it "wife thinks I need a new car" mode.

Originally Posted by harkes

My bad - should have checked the log first Def not the same problem. -8.6psi at idle......WHAT?? Try throw a new MAP sensor at it.

Yeah, that -8.6psi is what motivated to me to post after seeing the log. The fuel trim, RPMs, timing all seemed to be funky. I need to log again but I suspect that was some kind of anomaly.