voodoo curse = found! lean condition narrowed down, critical update! MAS + decel

[peanotation]

per this thread (don't need to read it if you havn't, just for reference):
https://www.thegalantcenter.org/showthread.php?t=37319

i'm excited to say that i've narrowed it down to my problem. who's ready to troubleshoot!?!?!


so ever since i've had this lean condition, i've had the MAS harness extended and i get some random popping from the exhaust under heavy engine braking. to elaborate, when i went turbo back in the day, i had to run the MAS further away from the harness, so i simply cut the harness and twisted on new wires. when i was troubleshooting everything in the thread above, i went back to the MAS harness and soldered the wires (i had only twisted them together before, no solder) as a way of ruling out a poor connection or something. as for the popping in the exhaust, if i'm engine braking hard (RPMs are high in a low gear) the exhaust will project loud popping randomly, like the car is backfiring under decel. again, only at high rpms with the vacuum at like -25.


so over the past two days, when i'm decelerating at all in gear with anything from light to hard engine braking, i get a check engine light and the popping/backfiring in the exhaust is more frequent and louder than normal. Also, the car cannot idle anymore! for months i had a solid, smooth idle that never fluctuated, with a TPS sensor in spec. grounding the #1 pin for OBD1.5 gets code12 from the CEL flashes, Airflow Sensor Fault.

i have two MASs that i know to be good, my original one that never threw a CEL before and one from a donor 7G with 100K miles that never threw a CEL either. i find it VERY unlikely they both went bad at the exact same time, with one sitting in my closet in my room and the other being used. i've switched between the two of them and i still get the CEL for Airflow sensor fault and more backfiring than usual.

btw, this is what my sparkplugs look like: https://www.thegalantcenter.org/showthread.php?t=38222

so what does all of this mean? i'm confident this is the main symptom of my problem, considering i've replaced or rechecked everything under the sun, even running a new ECU!

[mko]

Matt, make sure the extended wires go to the correct pins. I had a similar problem with my Evo MAS when soldering the Evo plug to the Galant wires. I had one wire wrong and I was getting codes from all sensors in the MAS.

Also make sure you get the correct voltage on the airflow pin 2.2 - 3.2V with the engine running