Cold start idle issue

[sdbmwcoding]

Hey everyone. Earlier this year I noticed that my cold start idle will dip down pretty low and come back up. It's never stalled but it consistently dips low and comes back up every cold start. This doesn't happen once the car is warm, only on cold starts. Doesn't happen after getting fuel. I've been reading it could be the Fuel breather valve or idle control valve. I get 0 codes, I have new plugs as well. Everyone I've spoken to says fuel breather valve but I read that the symptoms aren't just on cold start. You'll get idle issues randomly and after getting gas. Before I replace the fuel fuel breather valve or idle control valve does anyone have any insight on which one they think it can be? The car is currently completely stock.

[sdbmwcoding]

Bump

[mapster37]

i had a similar issue, my car eventually threw a code for fuel pressure sensor. after replacing havent had any more issues

[sdbmwcoding]

Originally Posted by mapster37

i had a similar issue, my car eventually threw a code for fuel pressure sensor. after replacing havent had any more issues

How long did it take before throwing a code? It's been about 6 months with the cold start idle, it hasn't gotten worse and never stalls so I left it as is for a while but now that I got some free time during the summer I wanna figure it out. No codes at all in the last 6 months.

[mapster37]

it was a few months best guess, not 100% sure. the sensor is not that much to purchase anyway

[ha9981]

So I've had funny idle too. It seems more like fuel pressure sensor. I bought that and the breather valve.

I wanted to test to see if the breather valve just needs to be cleaned. Everyone replaces it due to the effort to get there.

The fuel rail pressure sensor is more work to diagnose as explained here: https://axleaddict.com/auto-repair/H...sure-Regulator

[dozaiya]

Originally Posted by ha9981

So I've had funny idle too. It seems more like fuel pressure sensor. I bought that and the breather valve.

I wanted to test to see if the breather valve just needs to be cleaned. Everyone replaces it due to the effort to get there.

The fuel rail pressure sensor is more work to diagnose as explained here: https://axleaddict.com/auto-repair/H...sure-Regulator

were you able to pinpoint the cause?

[akkando]

Originally Posted by mapster37

i had a similar issue, my car eventually threw a code for fuel pressure sensor. after replacing havent had any more issues

The low or high pressure sensor?

[akkando]

Update for me. Checked gas cap. Wasn't fully tight, fixed that Cold start idle now is 80% better.