Im basically gonna write my whole life story so i don't miss anything. i bought the car with 141,xxx miles on it, its a 93 Z28 A4. when i got the car i was told that it was going to need a new fuel pump soon, that sometimes it had issues starting on cold mornings. I immediately noticed that the Coolant Temp Sensor (CTS) was unhooked and zip tied off for some reason. Not knowing anything about these cars, or LT1's i left it as it was. after driving it for so long i finally decided to change the fuel pump, skip past the installation and bam, my problem still persists as far as taking a long time to start, rough idle, missing, check engine light.. Maybe not quite as bad but its still there. After looking under the hood i decided to plug the CTS back in and BAM, car starts first time every time, no miss, no rough idle, check engine goes off. After driving like this for so long i start to notice now that when revving out second i get a miss and loss of power, and when im 3/4 to full throttle black smokes come out of exhaust. I replaced the CTS thinking that could be the issue, no difference after that really. finally did the old paper clip trick on it and got my trouble codes. a 44, 55, and 61. did some research and found out its for a bank 1 O2 Sensor. and low performance A/C, obviously.... anyway i go to town last night and pick up a O2 sensor. this morning i go to start the car and the idle is low (around 4 or 500 rpms) and it even died out on me.
***** main question right here. Could the low idle be contributed to the O2 sensor, or could it possibly be the CTS i replaced. im not getting any codes for the CTS even today so i dont think its that, but im pretty sure i have had the O2 Sensor problem for a couple months now already and it has never low idled like that before, except for when my old CTS was unplugged

 

55 is a ecm error. check to see if someone has put a chip in it. could be failing. brb

 

in the cubbie between the passenger side wheel well and the fire wall you will find the ecm, looks like this



the light colored part comes off to reveal the prom. it should look like this without the added green part. just the blue and brown parts. it plugs into the ecm

 

i keep reading everywhere that a 55 is a lean fuel monitor. and 44 is Lean Exhaust detected from O2 sensor

 

so it should not have the green Part?

 

if your changing one 02 sensor you should change both. are you getting a gas smell in the exhaust?

 

from time to time i suppose. Where are they both located? i know one is before the Cat i think

 

lol, had to look it up, your correct. 93 book shows lean fuel monitor. have you tested fuel pressure?

 

first off try doing a full system reset. take both battery cables off the battery and hold them together for a minute,,, well 20 seconds anyways. this should reset all your systems. they will have to re learn so it will run funny for a few runs while it re learns how to adjust everything. it will also clear all your codes so you will not be seeing any old codes but it will reset codes that are still present. also if you have any capacitors or a backup battery you will want to disconnect. it should clear your radio settings as well.

 

hold the positive and the negative together for 20 secs? ive never had to do it like that before lol. but okay