another "rough idle" thread, different symptoms

[OreoGaborio]

aight... so i just finished my 325i exhaust install on my Eta & i had my fingers crossed that a new O2 sensor would fix my idle problem that i've had for a few weeks now, but knew it probably wouldn't..... and i was right... it didn't

Start the car cold (i've had to tap the gas lightly a couple times right after it fires up since forever, otherwise it would just fire up then die).... idles high, around 1k rpm's (cold start valve i assume) then a minute or two after it starts warming up the idle goes way down to about 300 rpm's, just BARELY hangin on for life. does this for the next 10 minutes or so untill the engine is fully up to temp & then it's usually fine

my first thought is the Cold Start Valve, but the first minute or two after start-up is fine, other than being a little high

thoughts?

[Brew]

Well a weird idle at start couldn't be related to the O2 Sensor anyways. The engine doesn't read off the sensor until its warmed up.

It could be a number of different things, I think.
How's the AFM?

[OreoGaborio]

Well a weird idle at start couldn't be related to the O2 Sensor anyways. The engine doesn't read off the sensor until its warmed up.

It could be a number of different things, I think.
How's the AFM?

yeah, that's why i figured it wasn't an o2 sensor & the AFM should be ok

here's another symptom.... when it's having a tough time staying alive, if i bring up the gas myself for a little bit & let off the gas it idles fine, then starts having trouble again

[Brew]

Have you ever tried swapping ECU's with someone who has good idle?

[EtaSport]

Ever unhooked your o2? Shouldnt be a problem since its new, but i had erratic idle and i dont even run mine anymore, runs very smooth. The cold start doesnt even run for more than a few seconds. If you want to test it, pull the valve out of the intake and start the car up. Have a cup ready to catch the spray, and check for a clean cone pattern. You have to watch because if its working right it should only spray for like a second or two (yea, make sure the car is cold too.. )

Other things to check, tps. You can test it with an ohm meter, but could be to blame. And those temp sensors up by the thermostat. Check those out too. You should be able to use an ohm testor on those as well. Third thing is the AFM. Even if you think its fine, just pop the black cap off and move the needle from closed to open a few times, make sure its contacting and what not. After replacing about every electrical piece in my motor, I still believe that the AFM was to blame for richening my fuel and causing my car to stall at every stoplight, as well as consume about 15 miles per gallon. Last thing i can think of is fuel pressure regulator, and fuel purge valve. Check em out too.

[OreoGaborio]

thanks for the tips guys.... by the way, my Gas Milage isn't bad at all.... average about 28 a tank, 80% highway

[pogiboy9]

Do proper checking procedures to test all the switches and valves, from the bentley manual.

-neil

[PJ325i]

Make sure you check the harness under the throttle body that is mounted on block in a bracket. This harness controls the injectors and other functions.

Mine was green from corrosion. The coolant hose on the throttle body is infamous for leaking down on that harness.

I had all kinds of starting and idle issues. It even made the engine light flash a few times. Once that was cleaned, all the problems disappeared.