rough idle, dying after start (on RARE occasion)

[T.Bird]

So, twice since I have owned the ZHP I go to start it and have issue. The car idles extremely roughly between 600-1000 rpm. When I give it gas it will rev just a bit, then die when I let off. On the third start the car was perfectly fine. The first time this happened was almost a year ago, a month after I bought it...and I can't remember the circumstances. But this time, the car had not been started in 3 days (other than for 5 seconds the day before to move the car over to get the lawnmower out). Is there some kind of issue with these cars if you start them and not let them warm up or run for a bit?

[llll1l1ll]

AFAIK the general consensus is to simply start your vehicle, ensure stable idle, and go. You don't need to wait 30 seconds unless it's blisteringly cold outside. It sounds like you might have a fuel or ignition issue. I recommend checking for vacuum leaks, giving your MAF a good cleaning and even investigating your fuel filter. If that doesn't work, how old are your spark plugs?

It's strange that on the 3rd time it's fine.

[Jlastor]

I always like to let the car warm up a little every morning (independently of brand of car), even here in Puerto Rico with 80+ degrees year round. I like to make sure oil has run through everything before getting the revs higher.

But regarding your issue I'm also interested to know what's causing it. I don't have that issue but since I'm new to BMWs I want to get to know the most of them. I thought it was a VANOS issue when I started reading but since you said that it went away on the third start, I'm coriuos.

[billschusteriv]

When/where/how many miles ago did you get your last tank of gas?


My e46 touring is doing something similar. I'm also getting the "Service Engine Soon" light with several cylinder misfire codes. The touring started idling like this just a few miles after filling up at a local gas station (<6 miles on the tank). My indy mechanic thinks it might be a bad tank of gas (e.g. water/sludge). He recommended I pick up some DryGas or fuel treatment that handles moisture (e.g. Seafoam).

We're going to replace the fuel filter and a nagging O2 sensor (to minimize the chance this is compounding the problem and fix it before it really fails).

[mikeyb74]

My e46 did the samething when the intake camshaft position sensor was bad.

[billschusteriv]

My e46 did the something when the intake camshaft position sensor was bad.

Ooooo... good data. I will pass that along to my indy mechanic.

[telijah]

Should be throwing a code if one of the cam position sensors was failing. Consensus is if only one is failing, the car should still run (I have only one failing right now) without issue, but if both are failing, it will have the symptoms you described.

[mikeyb74]

When mine failed the car would stall at idle or when I stopped. Also when I replaced the cam sensor another code came up for the fuel tank breather valve.

[billschusteriv]

What code will you see if a cam position sensor is failing?

[danewilson77]

what code will you see if a cam position sensor is failing?

p0340 / 0341 / 0345

List

P0340 Camshaft Position Sensor Circuit Malfunction
P0341 Camshaft Position Sensor Circuit Range/Performance
P0342 Camshaft Position Sensor Circuit Low Input
P0343 Camshaft Position Sensor Circuit High Input
P0344 Camshaft Position Sensor Circuit Intermittent
P0345 Camshaft Position Sensor A Circuit Malfunction (Bank 2)
P0346 Camshaft Position Sensor A Circuit Range/Performance (Bank 2)
P0347 Camshaft Position Sensor A Circuit Low Input (Bank 2)
P0348 Camshaft Position Sensor A Circuit High Input (Bank 2)
P0349 Camshaft Position Sensor A Circuit Intermittent (Bank 2)