[TheMidnightNarwhal]

I have been noticing my car when it's between cold and operating temp at a red light for example the car "shakes" and idle isn't stable. Happens ocsaionally every maybe minutes or 2 minute. I read on here that it may be missfire but if it did missfire can I only know with INPA or CEL would light up? It's not a lot though, like I think the car idles a 600RPM and it bumps to 800RPM and drops to 450-500 and back to 600RPM. Randomnly does it.

Also, if I turn on the AC full blast the idle is very smooth at 800RPM and no drops.

[atmosphericM]

When my 328i misfired, at first there was no CEL. After I pounded her a few times I finally made a CEL come on. No flashing, just lit. Then it went away after a mile or so.

[Pladi]

CEL comes ON only after a number of Misfore counts have reached. Cars misfire all the time but you dont want to see alot of misfire. If you notice misfires while idling it will get worse. My suggestion is replace all coils and spark plugs proactively.

[TheMidnightNarwhal]

Originally Posted by Pladi

CEL comes ON only after a number of Misfore counts have reached. Cars misfire all the time but you dont want to see alot of misfire. If you notice misfires while idling it will get worse. My suggestion is replace all coils and spark plugs proactively.

I'll wait.

It seemed to have fixed itself for now.

[atmosphericM]

Yeah that doesn't sound like a misfire anyway - sounds completely normal IMO.

[Bimmer Pleaser]

In my opinion replacing the coils proactively is just a waste of money. I have seen coils fail as soon as installed, after 100 miles , 50k miles ... most of them go over 100k without missing a beat.

Just replace them when they fail.

[e90yyc]

Originally Posted by TheMidnightNarwhal

I have been noticing my car when it's between cold and operating temp at a red light for example the car "shakes" and idle isn't stable. Happens ocsaionally every maybe minutes or 2 minute. I read on here that it may be missfire but if it did missfire can I only know with INPA or CEL would light up? It's not a lot though, like I think the car idles a 600RPM and it bumps to 800RPM and drops to 450-500 and back to 600RPM. Randomnly does it.

Also, if I turn on the AC full blast the idle is very smooth at 800RPM and no drops.

Had exactly the same issue. Was annoying as hell because I could really feel the shake when it would happen.

RPM's would be good, good, good, then dip. And repeat.


Changed plugs. Issue disappeared. Returned about 6 months later. Swapped coils. Haven't had an issue since.

In hindsight, I also realized I was regularly getting some misfiring just when I would really dig into the throttle at city speeds. Since changing the coils it's much smoother overall.

I'd make a hefty bet that your issue would be corrected by replacing your coils (& plugs if they're due).

Just my $0.02

To add: I agree that replacing coils proactively is unnecessary; however, it doesn't really sound like a proactive replacement in your case, assuming your issue is what it seems on the surface.

[TheMidnightNarwhal]

Originally Posted by e90yyc

Had exactly the same issue. Was annoying as hell because I could really feel the shake when it would happen.

RPM's would be good, good, good, then dip. And repeat.


Changed plugs. Issue disappeared. Returned about 6 months later. Swapped coils. Haven't had an issue since.

In hindsight, I also realized I was regularly getting some misfiring just when I would really dig into the throttle at city speeds. Since changing the coils it's much smoother overall.

I'd make a hefty bet that your issue would be corrected by replacing your coils (& plugs if they're due).

Just my $0.02

To add: I agree that replacing coils proactively is unnecessary; however, it doesn't really sound like a proactive replacement in your case, assuming your issue is what it seems on the surface.

Thanks for the input.

I'll wait until it becomes much worse then, depending on the price and see where I will order.