i have this issue that started at the end of december. the car runs lean under any sort of throttle at 1500 rpms and throughout the rpm band. it doesnt do all the time, but enough to where i dont want to drive it. car starts and idles no problem and when it drives its normal no issues. any thoughts?

Ive checked for vac leaks, tps is in range, full tune up, two wideband sensors, reset the safc and checked the wiring. im sure im forgetting some things. i only get to work on it during the weekends and when weather is good.

s4 na safcii, full exhaust. links to videos below. the bad rattling sound in video is safc and flashlight moving.

 

Do you still have the air pump and ACV?

 

no its blocked off. 5th & 6th ports are still being opened up with a backpressure tube through the midpipe

 

Have you checked fuel pressure? fuel injectors?

 

Looks normal to me.

 

saturday evening i stopped getting spark to the leading plugs. sunday morning i put another coil pack on. The car acted fine. I drove it around town, stopped to eat, ran some errands. afr numbers were fine. drove it to work( 1/4 mile away). no problems.

 

its still having that lean issue...weird thing is it corrects itself and runs fine.

 

im going to take a stab at the fuel system and take a look there.

 

It sounds like its running on one rotor when it goes full lean on your wideband. Like it in fuel cut on decel mode which it cuts fuel to a rotor so it doesn't cause bucking during low rpm engine braking. Is this throttle dependent(possible tps issue) or sporadic(maybe primary injector clip)?

I would reset the tps to what it should be(1vcd engine hot at ecu plug) and if you have access to a analog multimeter use it to check the sweep of the tps for a potential bad spot.

 

Update: Tuesday I replaced the tps & fpr at the same time. It's been four days and it's been running great. No issues. Car feels great throughout the entire rpm band.

I'll be satisfied after the weekend. Lol.