This O2 sensor/heater problem is RIDICULOUS!! help!

[lolcantturn]

Hey guys. I've been getting fluctuating idle and when I rev the car to a certain RPM to try and keep it there, it won't hold steady, for example if I rev to 3k it'll stay there for about 4 seconds, then rev down to 2.5k, then up to 3.5k. In addition I get sputtering under load occasionally which is extremely annoying. I checked my O2 and that seemed to be wired fine. I then did the 12V backfeed and put in all new relays and that seemed to do the trick. The car ran smooth as ever! This lasted about four days. Today it was raining pretty dramatically in my area and on the highway going up bridge in 3rd gear the car hesitated just a LITTLE bit which made me extremely worried that it was going to happen again. I went sliding around in an industrial park in the pouring rain where there were puddles and my car bogged down HARD. It was almost as if the water was affecting the O2? This all started occuring when it was raining outside..however now that it's dry my engine still does not run smooth like it used to! I checked the O2 wires and they seemed to be all connected and dandy and the backfeed is still holding in place.
What the F*** gives!! This is EXTREMELY annoying. If you're in NJ, I will PAY you to fix this problem. It is extremely annoying for a daily driver car to be doing this.

[lolcantturn]

Bumpity!

[dirty30]

there was a thread for fixing the O2 backfeed, just search O2 backfeed repair or something along those lines

[Beej '86 325es]

I'm still having issues as well.
I can't remember, were you getting 12V for heat at the sensor?

Here's my problem, do you have the same thing going on?
http://www.youtube.com/watch?v=WjvLuaXvGH0

I'm about 5 minutes from just installing a damn jumper in place of the relay.

[trackjunkie21]

I'm still having issues as well.
I can't remember, were you getting 12V for heat at the sensor?

Here's my problem, do you have the same thing going on?
http://www.youtube.com/watch?v=WjvLuaXvGH0

I'm about 5 minutes from just installing a damn jumper in place of the relay.

Hmm it seems your car idles a bit high, lightened flywheel? I can't remember exactly but isn't the CTS ran through to the 02 heater wiring? To trigger when the heater comes on? I'm having a similar problem as you both. Car sometimes doesn't want to idle very clean when coming to a stop, but this happens rarely. It will surge from 500-900 and sometimes even drop below 500. And then there are the random cut outs, car always starts back up again.

[Beej '86 325es]

Yeah, the idle has been upped to account for the lightened flywheel. Also, it is a built motor.

If the coolant temp sensor interacts with the O2, it would be internal to the DME, they don't share any wiring. I tested my sensor as good, even though I installed a new one when I built the motor.

[r4esh]

Was there ever a conclusion / fix to this?

[Rugbyfan]

I remember when Dave Markert was re-doing my harness while it was on my car. I brought up the "o2 sensor heater" problem and his response was something along the lines of "I've never had an issue with it". What I'm getting at is that if this issue is driving people nuts, get a perfect harness from an expert at wiring. While I really like doing things on my own, If I want something perfect, I go to the source.

****didn't notice the post bringing this thread back from the dead. Oh well I stand by my advice.

[Beej '86 325es]

I'm not sure if lolcantturn got his straightened out, but I eventually figured out that the O2 heater relay behavior in my video was normal and something else was causing my rough idle.

[r4esh]

Found a split in my hose that runs from the intake to the idle control valve... stupid, but easy fix... it was really subtle I had to inspect the hose closely to finally spot it, but after changing that my idle returned to normal.

[e30shmobberr]

http://www.r3vlimited.com/board/showthread.php?t=192533