Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
So, I've been in the heavy diesel industry for almost 20 years and have always enjoyed challenging diagnostics. Now that it's on my own vehicle it is proving to be frustrating hahaha. I'm working on a 2006 Ford Escape 2.3 FWD auto, with 215,000 kms on it. It is an auction vehicle so I don't have any history. The unit is running rough at idle, sometimes it will stall. Off idle it runs smooth, but there is black smoke from the tail pipe when taking off from a stop. There are no codes active or stored. I have checked it with a thermal imager, and cylinders 1 and 4 are 25~ degrees hotter than 2 and 3 during warm up. Idle speed fluctuates between 620 and 750 RPM. If this was a vacuum leak, wouldn't the IAC percentage be lower? I would really appreciate a little bit of direction on this one.
At idle:
MAF 3.18-4 gm/s
MAP 15
IAC 33%
IAT is correct
Baro in/hg 28.0
STFT +2-5
LTFT -4
The fuel trim you posted is unremarkable, all though with black smoke at idle one would assume running rich. One thing I might do in your position is verify the oxygen sensors can report rich and lean.
Baro is what I see close to sea level, MAF maybe a smidge high depending on the RPM. Since you have no repair history have you checked the plugs, fuel quality?
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