[Lochstar8]

For the past 6-8 months my 2007 e90 323i (200hp) has idled kinda funny. It starts no problem and stays running no problem. But on initial start up it jumps to 1300 rpm as usual then drop down to around 800 sits there for 3-5 seconds then go back up to 1100 rpm wich i believe is normal cold start idle. But every 5-10 seconds it will go between 800 and 1100. It will do that about twice then just stay at 800. Till it's warmed up some then drop to the normal 650 or 600 can't remember. It doesn't do this when it's warm it's only on cold starts. And is most prominent around 10°C to -15°C

The car dosen't get driven super often( about 2–3 times a week) some times less and unfortunately sits outside.

:It's had spark plugs about 5000km ago
: Oil change about 6000kms ago
:I have removed and cleaned the throttle body( was more responsive after that)
:MAF and VANOS solenoids have both been cleaned recently as well as the VANOS check valve/filters were also cleaned. (less then 500km ago)
:The coils have never been changed and the car has 298,000 Km. But has never broken up under WOT or at 6000 rpm+ or at least that I have noticed.
: dosent feel like there's any lack of power.
: valve cover gasket and oil pan gasket were replaced 6000km ago. And this problem only really started after that but it's hard to know because the car sat on jack stands for 6 months while that was happening. It's possible that the CCV hose at the back of the valve cover was damaged but unlikely.
: it also just went in for the recall were the put in a fuse for the PCV heater.

Fuel trims are all good the oddest one out is +7%

I'm looking at getting INPA so I can reset adaptions and stuff but haven't got it yet.

And absolutely zero codes for anything on the car.

The odd time it does seem like it may have a misfire for 1-2 seconds but the car doesn't detect anything and doesn't throw a code.

Any ideas?

-Loch

[NZE90]

Have you ever checked the operation of the DISA valve in your manifold? I had a similar thing with my 323i and it was the DISA valve flap stuck open.

[NZE90]

After i upgraded the manifold to the 3 stage with 2 DISAS and flashed it to 325i spec it was fine.

[Lochstar8]

Originally Posted by NZE90

Have you ever checked the operation of the DISA valve in your manifold? I had a similar thing with my 323i and it was the DISA valve flap stuck open.

Originally Posted by NZE90

After i upgraded the manifold to the 3 stage with 2 DISAS and flashed it to 325i spec it was fine.

I haven't checked the operation of the DISA valves. And definitely is not a bad idea considering I have the 3 stage intake. I will have to buy a INPA cable to test that properly. I should have bought one a long time ago considering a have 2 cars with N engines. Thanks I will try that soon.

- Loch

[Lochstar8]

Originally Posted by Lochstar8

I haven't checked the operation of the DISA valves. And definitely is not a bad idea considering I have the 3 stage intake. I will have to buy a INPA cable to test that properly. I should have bought one a long time ago considering a have 2 cars with N engines. Thanks I will try that soon.

- Loch

I got the cable and tested everything in the car, that INPA and ISTA would allow me to. I could hear both DISA valves open and close and were reported correctly on screen as well. and And after resetting all adaptions it has solved the weird idle. What was causing it im not sure but. The biggest and most noticeable difference after resetting the adaptions was throttle response and different pedal sensitivity. It feels like the pedal is more sensitive at the beginning of its travel. Wich is quite nice makes it feel more sporty. As I was testing the throttle body with INPA you can open it different amounts. I commanded it to open 99% open or full throttle. And it only showed it opened 80.2% percent.
Wich I found odd. But didn't worry about since the extra 20 percent would make little difference.

[chilledn52]

I had troubles with cold starts at one point with my valve cover, I would look into your PCV Valve / new valve cover. PCV valve thats ripped or torn or a crank in the plastic manifold can cause similar problems

[Suvorovo]

Originally Posted by chilledn52

I had troubles with cold starts at one point with my valve cover, I would look into your PCV Valve / new valve cover. PCV valve thats ripped or torn or a crank in the plastic manifold can cause similar problems

A good PCV will make a fast blub blub blub sound when you open the oil fill cap while the car is running. I have the PCV on the intake manifold, not sure if it's the same for the plastic valve cover with integrated PCV N52s.