M42 gods... Shine thy light.

[duleymane///iS]

Good morning, afternoon, evening.
So a little background. I have done the mess under the intake mod. Did it about a year ago and car has performed phenomenally. It's been on the Nurburgring, done an Autocross day, has been the victim of countless clutch drops and cone smacks. The only thing.. ONLY THING that pisses me off is this damn idle. I have double, triple checked all my vacuum lines they are all new, every gasket new, ICV has been cleaned twice and yet.. to my dismay my idle sucks. I even reset the ECU and it helped I even posted on here like 2 months ago how happy I was. but its back. I reset it again.. still poop. Can it be the fact that the engine is 23 years old, has 300,000k+ on it, when I replaced the oil pan gasket there was no plastic or metal in the pan and the crank looked SUPER clean. My top end looks great too except my cam gears. Am I missing something? I have included 3 videos 1. A cold start at about 60 degrees outside, 2. small 3/4 throttle pull up to 5k rpm to show she still pulls with no hiccups, 3. and a fully warmed up drive through a parking lot to show that even warm the car still idles crappy. Also, throttle response sucks which leads me to believe its something in the intake tract.


Cold start: I hold the throttle for a little at 1000rpm and then let it go.

http://youtu.be/R_CKEXepUQc

Slightly warmed up: Just pulling up to 5k at about 3/4 throttle. Pulls strong.

http://youtu.be/wkUlaVtvI7o

Fully warm, still dying out and throttle response is not perfect.

http://youtu.be/hTVxAHIN3-g

[Dj Buttchug]

what is your o2 situation. new? old? are you running the grey wire plugged in or not?

[duleymane///iS]

havent messed with the o2 sensor besides wiring it up like you all suggested. the grey wire is not plugged in. if i plug it in the car will not move it just hiccups and backfires and then dies.

i think my car is running too rich to be honest. heres why i think this correct me if i have mislead myself..
1. my car shoots fire.. and its stock..
2. when warming my car up it spits out condensation, as most cars do.. yet mine comes out blackish and smells like fuel. i tried to light it on fire but no luck.
3. all my vacuum lines are new, and new intake/TB gaskets. still shitty throttle response.

[Dj Buttchug]

if it were me id try get pin point the rich condition first. hows the fuel delivery system? FPR? filter?

[benz-tech]

Sounds like it could be an FPR. But have you replaced the iac valve? My idle deteriorated even after I cleaned it. Fixed with a new one. What's your O2 voltage? If its sweeping from .1-.9volts or so, you are not running too rich and the smell could just be a bad cat. See if you can borrow known good parts before buying expesive stuff

[duleymane///iS]

Sounds like it could be an FPR. But have you replaced the iac valve? My idle deteriorated even after I cleaned it. Fixed with a new one. What's your O2 voltage? If its sweeping from .1-.9volts or so, you are not running too rich and the smell could just be a bad cat. See if you can borrow known good parts before buying expesive stuff

LOL i dont run a cat. its Germany not required. and ok I will check all of this. thank you.

[duleymane///iS]

if it were me id try get pin point the rich condition first. hows the fuel delivery system? FPR? filter?

fuel filter is about a year old around 30.000km, should i try replacing the FPR?

[n2motorsports]

iirc - a bad o2 will cause you to run rich

[kwill22]

In my experience bad idle has been cause by either::
Vacuum leak(which you've checked)
Cam sensor
O2
Timing off

Assuming your fuel system checks out. Just test each thing and eliminate as you go

[Dj Buttchug]

see heres the thing. from my understanding all euro m42 cars running no cat are suppose to have the grey wire hooked up.

I swear I remember reading this somewhere. someone chime in

[M3Philipp]

Exactly. The grey wire in the enginebay needs to be unplugged, with cat.
If its plugged in, the car will start very bad when its on temperature now and then.
Like just running on 2 or 3 cylinders...

[duleymane///iS]

Yes I have no cats, and it's unplugged. When plugged in cant go anywhere. This is why I am baffled; it was 33 degrees Fahrenheit this morning and held a decent idle.

http://youtu.be/-10z0qu_I6U

[duleymane///iS]

In my experience bad idle has been cause by either::
Vacuum leak(which you've checked)
Cam sensor
O2
Timing off

Assuming your fuel system checks out. Just test each thing and eliminate as you go

Gonna start with the o2 sensor just ordered one. Hopefully its here by the weekend but these APO mailboxes aren't known for quick deliveries. I kinda feel blessed that we only have 1 o2 sensor. My buddy owns 2 Fords an Escape and Fusion both with the 3.0L V6, both have 4 o2 sensors and they are both throwing CEL codes for bad o2 sensors. ALL OF THEM and here I was complaining about 110 for 1 lol :D

[brianf408]

Mind if I tag along in this thread as well? My idle is exactly the same, bounces between 750-1250 RPM. Clean ICV, no vacuum leaks, no CEL. Only difference is at 3/4 throttle or more I get a little misfire/stutter at off-idle as well as around 4500 RPM. US spec with cat, no clue as to the age of the O2 sensor. New fuel filter is in the box should go on tonight. Don't want to throw any more parts at it just to guess at the fix.

[roguetoaster]

Mind if I tag along in this thread as well? My idle is exactly the same, bounces between 750-1250 RPM. Clean ICV, no vacuum leaks, no CEL. Only difference is at 3/4 throttle or more I get a little misfire/stutter at off-idle as well as around 4500 RPM. US spec with cat, no clue as to the age of the O2 sensor. New fuel filter is in the box should go on tonight. Don't want to throw any more parts at it just to guess at the fix.

If you suspect a sensor or two, unplug one at a time, if the condition remains the same you have probably found the culprit, clearly if it gets worse that's part is probably working.*

*(exceptions apply, use common sense, & etc.)