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Alright I need some help. I have a BMW with a 5.3 swapped into it. About a month or two ago I got a base tune put on the car, and it was running good and idling well. Here is a video showing how the engine was running
. I drove the car a handful of times around the neighborhood, and it ran okay however I never got over 30 mph max. A few days ago I finished my exhaust out the back of the car. Nothing crazy just a 3" y pipe, through a Borla XR1 muffler, and then 3" all the way back. I fired the car up after the exhaust was done, and the car seemed to run just like normal. Here is a video once the exhaust was done https://www.youtube.com/watch?v=XVQv...ature=youtu.be
The car sat for a week or two and when I recently went to start it up. It is running extremely rough, and very very rich almost like it was before I got the base tune. Here is a video from it running today
. I pulled the plugs and they were wet with gas (see below). I thought I might has a bad coil or wire, but I tested all the wires/coils and had spark at each one. I changed the plugs hoping that would help, but it didn't. The car still runs the exact same.
I hooked my scanner up to the OBDII port and I pulled two codes. One is a P0505 - Idle air control system lower than expected, and the second code was a P0650 - malfunctioning indicator lamp. I also snapped a few pictures from the OBDII bluetooth gauges while the car was running (see below). The battery voltage seems low, and the O2 Sensor readings are high. Also it seems like the MAF readings are high, but I am not 100% sure.
Any help anyone can offer to point me in the right direction would extremely appreciated. Please let me know if I can provide you with any more information.
Check for exhaust leaks ahead of the O2's. Air leaks in, fooling the O2's into thinking it is a lean mix, throwing way more fuel into the mix, making for a VERY rich mix.
I've seen this twice. First was a broke (stuck iac valve) second was my car was too low and banged headers on asphalt, then upstream o2 sensors immediately went to poop. Both times simple parts fixed my stupid problem. This may not help you much, but I'd start with that... Happy wrenching sir..
Check for exhaust leaks ahead of the O2's. Air leaks in, fooling the O2's into thinking it is a lean mix, throwing way more fuel into the mix, making for a VERY rich mix.
i did notice that when I changed my spark plugs it looked like there was a little bit of an exhaust On the the plug insulator. I retourqued the exhaust bolts to the heads, but didn’t seem to make a difference. I have a evap smoke machine coming and plan to smoke test the engine.
Wanted to close this thread out. I smoke tested the engine, and quickly found out what the issue was. My MAF housing had cracked behind the sensor allowing extremely high MAF reading. I have replaced the senor housing and the car runs good now. If anyone has an issue similar to this, and car read the MAF senor the values should be around 2 to 3 lb/min. Mine was reading around 67 lb/min.
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Sudden Rough Idle 
