weird issues and no start

[gtdragon980]

So i've been dealing with this idle issue for about a year now and i've been narrowing down things and slowly making the car run better. It is an '89 325i and has very low miles. It first started with the high idle which was fixed after replacing the tps. During that process, I replaced the AFM, o2 sensor, and fixed vacuum leaks. Recently after fixing that, I was left with a rich fuel mixture that has me pulling my hair out. So on to what has happened today, after fixing the ground that I broke off (the one on top of the passenger strut housing, next to the coil.) I started her up and she idled as usual. Really low and really rich with terrible throttle response. I unplug the ICV and notice it doesn't really affect it. After plugging it back in a unplug the AFM, and all of a sudden it seems to be idling perfectly at a seemingly stoich mixture. I rev the engine and the throttle response is better than ever! After it settles, I plug the AFM back in and its back to its rich and low idle state :(. So I unplug the ICV another time and still not much difference, and i unplug the AFM at the same time if I remember correctly and the idle shoots up to 2k until i plug the ICV back in and it settle somewhat. Then i plug the AFM back in and its back to the normal shitty state. I decide to take it for a spin and as i get to the bottom of my driveway the throttle response gets worse and suddenly the idle shoots up to 2k. I get out and take a look under the hood and wanted to see what was causing it, so i unplug the ICV and nothing happens, and then i unplug the AFM and the car sputters and dies. I tried starting it like that and it starts but doesn't hold an idle. I then plug it all back up and try to start it and it does not even catch a little bit. So now I'm stuck at square one trying to get this damn thing to work correctly!! Sometimes I really hate my car. /rant

But does anybody have the slightest clue as to what is going on with my car?? Any help is appreciated! Thanks!

[jlevie]

In this case the improvement when you unplug the AFM sounds like it could be a bad or sticky AFM.

[gtdragon980]

The thing is I replaced the afm not too long ago with one that had only 3k miles on it. I also checked the fuel pressure and it came out good if that helps. Shouldn't the icv have some effect on the idle?

[gtdragon980]

new symptom, it started today with a very rough and low idle and after a few minutes of running, the idle raised up to around 900 rpms and i hit the gas pedal and it sputtered down and died...

[gtdragon980]

well, after toying around with sensors, i found that when i unplug my engine temp sensor (not coolant temp) it allows my car to run somewhat better, and allows my to rev my engine without it sputtering and dying. i am replacing this tomorrow and seeing what happens

[gtdragon980]

well no luck with the sensor, same old shit. gonna try some other things and see where it gets me. ill try to get a video up on how it sounds and hopefully someone can analyze it.

[jlevie]

What you are proving by disconnecting the AFM or engine temp sensor is that the engine runs better in open loop mode than in closed loop mode. That in turn tends to suggest that you have intake leaks and/or a bad O2 sensor. Since the useful life of an O2 sensor is not more than 100k, if that applies replace the sensor and have a smoke test run on the intake.

[sl0ride]

Have you checked for vacuum leaks? Or spraying carb cleaner and cleaning the afm and ICV?

[gtdragon980]

well i found one vacuum leak from the valve cover and i believe another one at the icv connecting to the throttle body. now what my question is, would this cause my car to run rich? it literally blows greyish, blackish almost diesel looking smoke out the tail if i give a good amount of throttle. i pulled the fpr, but it doesnt seem to be bad. what should i look for to tell if it is bad?

[sl0ride]

Vacuum leaks will deff mess with your idle. Especially on the ICV hose to the manifold.
Repair the leaks then see if you still have the fuel mix and idle issues.

[gtdragon980]

so after messing with the fuel supply hose and fuel regulator, i tested the pressure and it seemed to be good. but when i unplugged the return hose and blew some air into it with an air hose while the gas cap is open, the fuel wouldn't go back into the tank. also, when you unhook those hoses shouldn't fuel spray out somewhat?

[jlevie]

Seemed good, or is good as reported by a gage tee'd in to the line that supplies the fuel rail?

If you could not blow air into the return line that connects to the FPR I'd say there's a problem.

[gtdragon980]

Well it wasnt a completely proper test due to the fact that we did not have a tee to test it, but we hooked the pressure gauge up to the supply and tested it and it showed around 38psi. And it also turned out i was blowing into the supply hose, so i checked the return and it was good, though it did make a gurgling sound. But after doing tht, i noticed the was some type of sensor that was hanging under the tb going towards the mani which was unplugged. I plugged it back up but it wouldnt start so im going to try and start it tomorrow and see what happens. In the meantime could someone educate me on what the sensor is that i found?

[gtdragon980]

Okay scratch that, it is the bypass valve that comes out of the charcoal canister. I plugged it in and started it up but still no success. Car still runs like shit, including hesitation, misfiring, rich mixture, etc.... I have got to be missing something. So far i have done..
-spark plugs
-TPS
-ECT
-AFM
-tested ICV and is good
-intake manifold gasket
-02 sensor
-valve cover gasket

cant think of anything else but im sure i've done more..

[gtdragon980]

After all the shit i went through, it was the measly c191 connector. When i first looked at it, it was corroded but i didn't think it was so much that it wouldn't give the slightest signal for the ECT. Turns out it was so i replaced each pin and socket and the car is running like a champ again!