Alright this is going to be a long one so stick with me. I have a 2000 civic hx coupe that i have been building for the past 7 months. I have a b16a that i have built for boost (rods, pistons, port&polish, ferrea valvetrain) the whole 9 yards. Anyways i got the engine back in the car about a month ago and have been having nothing but Headaches since. The first startup went great, it fired up no problem and ran pretty clean on that Base-map i received from my tuner. I took the car on its first drive to go get some gas and everything went great (Not smoking or any leaks etc.) when i got the car home i got on my laptop to calibrate my tps and the next startup after that is when i first experienced the idle sure. Long story short me and my tuner couldn't get the car to idle and just leaned towards something being messed up mechanically so i change damn near everything that could cause an idle surge (tps,iacv,map,ect,iat,tb gasket, intake manifold gasket, bled the cooling system added some extra ground wires, triple check every wire/connector on the harness with absolutely zero luck.) my tuner sent me multiple tunes just to rule out it being anything tune related. After chasing what we thought was vacuum leak for a few weeks one day i just unplugged my aem wideband sensor and the idle went completely solid... This left both of us absolutely clueless because all of the maps we ever had loaded onto the s300 have been in closed loop so the wideband sensor being plugged in should have no effect on how the car runs, it only gives signal to the gauge and the ecu for the a/f reading. I have had the signal wire hooked up to pin D10 on my jumper harness for almost 3 years now in the car without a single problem. I even tried to switch the signal over to pin D14 but i had no luck. The car will idle steadily on pin D14 but its rich as hell and the sensor wont recognize any change when adjusting the fuel map trying to get it to run a little cleaner. The reading i get on smanager is about .76 lambda which is about a 11.1 afr, the odd thing is my gauge reads 10.00 (maxed out rich.) i tried changing the power and ground wires to the gauge to different sources with no luck. At this point me and my tuner are pretty much out of ideas. I’ve put hundreds of dollars and countless hours Into the problem over the past month so absolutely any help would be greatly appreciated. Im willing to send anybody datalogs just to get a better look at things just shoot me a message.

Thanks,
Matt

 

Your test results seem to point to a faulty wideband sensor. Swap in a known good one. Then go from there.

 

a buddy of mine had a brand new haltech sensor laying around that i tried with no luck. I even tried using all 4 Wideband data log inputs on the ecu for the signal and grounding the sensor to the thermostat. Still no luck.