IAT Sensor and roughness?

[Tmccurry]

I was wondering if anyone knew of a relation between cylinder roughness and a tmic tapped gm style iat sensor.

 

The story: got a dumb p0304 with pfffee* misfire code. Did the basic coil/fuel injector/spark plug swaps and didn't help. Did a compression test on cyl2: 125/cyl4: 120. Became really confused and started looking at roughness.

 

Cylinder 4 on cold starts picks up a lot of roughness. It starts at 0 and climbs to a number and drops back to 0 and climbs again (it throws the p0304 at 90). It doesn't throw the code every day (every 2-3 days but roughness still exists on the start). Once warm roughness sits at 0. While driving roughness usually sits at 0 (I see occasional quick jumps as high as 4). No roughness ever under wot.

 

Friday morning I began wiggiling wires and decided to unplug my iat sensor during the cold start. The roughness and accessport paused on a number and didn't move. I left it unplugged and restarted the car, and the roughness stayed at 0 (I did get a cel for iat sensor circuit high). This made me thing my iat sensor is bad.

 

I called Cobb and they said the iat sensor should have no impact on the accessport being able to monitor roughness, further making me believe the iat sensor is my issue. However, I called the tuner who did my protune in co springs and they said it sounds like the iat sensor is working and since it was unplugged the system put in max fueling, which is what made the roughness go away. They said it almost seems like my cold start tables might be off, but that wouldn't explain roughness in only 1 cylinder.

 

any ideas?

 

The car has 99k miles 2005 LGT

Fp green

Id1000cc

Process west tmic with iat sensor tapped on bpv side

Running the lfr7aix 1 step colder plugs

Tuning alliance has been being super helpful with my sea level etune (came from co springs to ft Rucker, al) running 93oct