P2188 Rich Mix At Idle But All 02 Read Good

Ed Owner Gillette, Wyoming Posted   Latest   Edited  
2009 Mazda CX-7 GS 2.3L (3 MZR) 6-spd
P2188 - System Too Rich at Idle Bank 1
Long Term Fuel Trim Is Negative And Spark Plugs Are Sooted Up
Low Idle

After a test drive, the CEL light set with code p2188. At that time the long term fuel trim was -22 and unsure of short term. After some testing and more idling, the long term came down to -15 and short term was -2. After some more driving and idling, the fuel trims seem to have settled in at -12 and 0. The new spark plugs are black, but not wet. O2 sensor readings are withing spec and what I would expect to see on a typical vehicle. Have pinched off the purge line with no changes. High side fuel pressure is 425 psi. Air filter is good. Anybody have any thoughts, leaning towards checking the cam timing next but was looking for any other thoughts.

TJ Technician
Sault Ste. Marie, Ontario
TJ Default

Cold climate with short drives and vehicle not reaching operating temp? Seeing lots of issues with the oil having large amounts of fuel in it.

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Michael Owner/Technician
Tampa, Florida
Michael Default

Does the fuel pressure drop quickly with engine off. is the a gas smell under the oil cap like the Hpfp leaking into the crankcase

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Louie Instructor
Joliet, Illinois
Louie Default

This is a GDI engine the high pressure fuel pumps seal to the cam lifter is leaking fuel not uncommon check for fuel in the oil. 600 ppm HC engine off from crank case normal your will be 4000+ on most 5gas benches. Or remove oil cap and run engine with new oil and filter STFuel trim will get back to normal ish it will take 3 oil changes to truly get back to normal.

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Daryll Diagnostician
Seymour, Tennessee
Daryll Default

Does your scan tool have a fuel composition (alcohol content) pid? If so, what does the ECM THINK it is vs what is it actually?

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Darren Mechanic
West Allis, Wisconsin
Darren Default

Biased a/f ratio sensor.

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Fred Owner/Technician
Santa Barbara, California
Fred Default

Computer is trying to shut down fuel, is it possible to see injector pulse width with a meter to confirm the pcm is indeed shutting down the injectors? You mentioned pinching off the purge valve that's good, is all the spark plugs black or only 1 cylinder? Bias A/F and or 02s? Map or Maf, air and coolant temp sensors readings? Double check all inputs before going for cam timing, it's easier

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Eric Owner/Technician
Edgerton, Wisconsin
Eric Default

Ed, what is the customer complaint and how does the car drive? Need more information that what you have provided. How are the fuel trims under load and at highway cruise? Did you do anything while you were testing and idling? Something had to happen for the fuel trims to change while the vehicle was just sitting there. Readings at idle only is only about 25% of the information we need to

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Daryll Diagnostician
Seymour, Tennessee
Daryll Default

Do you have a 5-gas analyzer to confirm the a/f and O2 readings are actual?

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Scott Manager
Claremont, California
Scott Default

Hi Ed, Did you make any progress on this vehicle?

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Sean Diagnostician
Regina, Saskatchewan
Sean Default

Ed, We're you able to resolve this one??

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