The other day I went to start it and it constantly misfired. It’s doing multiple cylinders so while it probably does need plugs and coils (140k, owned it since 130k) I’m leaning towards fuel delivery, but I’m REALLY not a mechanic. Looking for some advice here
Also, if fuel sounds like a reasonable avenue of investigation to anyone else, I think I’m going to pick up a cheap kit off Amazon, $50 or so. Is there anything I should be looking for in a kit?
Check battery voltage before anything else. Modern BMWs are hypersensitive to weak voltage. Coils and plugs should probably be done anyway unless you have a record of them being taken care of; the plugs in particular could be far past their prime. As to fuel, there are specs for pressure and flow rate in the Bentley manual and in the online TIS. I don't know what sort of kit you're talking about, but if it's parts, forget it - just get the OE stuff.
I am going to guess MAF? Honestly, just do a spark plug change since it it easy and cheap.
Try unplugging the MAF and then see if the misfires stop. That will tell you if it happens open loop or closed loop which narrows down potential failure causes since closed loop utilizes front O2 and MAF to handle fueling.
I am sure the coils are fine but you could have a valve cover leak down the spark plug well causing misfires as well. Changing the plugs will give you a look down there just in case and tell u if any coils are totally jacked.
Can also move coil packs to different cylinders and see if the misfire moves any.
Sorry, by cheap kit I meant cheap fuel pressure test kit. Any recommendations for features for one of those?
and yeah I’ll try unplugging the MAF
P3PPY said:Sorry, by cheap kit I meant cheap fuel pressure test kit. Any recommendations for features for one of those?
and yeah I’ll try unplugging the MAF
You can rent one for free at O'REILLY. I am fairly certain fuel pressure will not be your issue but report back!
My 01 Z3 M54B30 would sometimes misfire on startup. Key off and on ("reboot") would clear it up. Weird.
I’m at 14.6 volts. hooking up a jump box made no difference.
Disconnected MAF and after initial stutter the misfire resumed as normal.
“Reset” with the key didn’t help
Update like one second later:
I turned it off and then back on again and the misfire has disappeared.
...???
any possibility of something like water in a line and a temporary ice blockage?? It’s been around freezing or below since this started but up to 37 today and it sat for two days in 20ish before exhibiting this behavior. It’s 33 right now. I don’t even know if that is a thing.
In reply to P3PPY :
Yes. The CCV line from the valve cover, and the valve itself, are both know to accumulate oil-water emulsion (especially when the car is used for short trips in cold weather) and, when it freezes, it will do a number of things, none of them good. Pop off the CCV hose from the front of the valve cover and have a look. If you want more diagnostics, rig up a slack-tube manometer to the valve cover and see what the crankcase vacuum is; spec is 4in H2O, which isn't much.
I designed a mod that increases crankcase vacuum and keeps the CCV clear. Search for "02Pilot Mod," or if you prefer I can send you a link to the full development thread over on Bimmerforums.
I haven’t read thru it yet but here’s the link
reduces oil consumption too?? Nice.
— about to go to work, I glanced thru it and I see I need a new dipstick tube and a vacuum hose? Is there a “kit” for this?
update: besides the dip stick tube (am I reading it right?) here are the instructions
No pictures right now, but it's very simple on the M54 (M52 may vary slightly). There's a single nipple on the middle portion of the CCV, between the oil separator and the valve; it is capped. Pull the cap off and connect one end of the line to it. The intake manifold connection is a similarly capped nipple on the back of the manifold; from the driver's side of the car, reach behind the manifold and you'll feel two capped nipples. Pull the cap off the small one and connect the other end of the line there. You'll need maybe 2 feet of vacuum line (very small diameter). That's all there is to it.
In reply to P3PPY :
Yep, that's the meat of it. You do need to pay attention to the caveats, however, as they are critical for safe and correct function of the mod.
- You need a properly sealed crankcase; any vacuum leaks are going to create a lot of flow through and maybe increase oil consumption.
- You need an intact and clear CCV system. I recommend just replacing the whole thing (four hoses plus the valve), plus cleaning the distribution piece and replacing the O-rings. The dipstick guide tube can either be modified (cut and weld after removing the problematic inner sleeve below the drain) or replaced with the updated design.
You will end up running a lot of vacuum in the crankcase, but my car ran for some 80k miles with the mod in place and there were zero negatives to this. Any questions let me know.
P3PPY said:
“Reset” with the key didn’t help
Update like one second later:
I turned it off and then back on again and the misfire has disappeared.
...???
Ha! Welcome to my world. My car is in FL so it was never temperature related. CCV is a real possibility or just good maintenance practice, although it is a bit of a PIA with brittle connectors and the dipstick tube. I've done it on an E46 M54 but never on the less spacious Z3.
In reply to glueguy :
As far as the CCV, just break the connectors and install new lines. They're probably going to break anyway eventually (usually when reassembling) - doing it at the start saves time and aggravation.
It ran fine today. I’ll have to look into all this I suppose
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