chazen

Hi, its a '99 with 160K.
Have read the threads RE: P0171 and tried to rule out vacuum leaks, leaks at the backside of the air filter and near the plenum ... all seems OK. Here is the Freeze Frame from two code reading sessions. Advice appreciated. Also, I live at 7500 feet and drive between 5500 and 10,000 feet regularly. Looking for direction and parts recommendation.
NEW INFO: Also, there is a P0171 code pending, and the PID Values when vehicle is running show that Bank 1, Sensor 2 has voltage all over the place - from 0 volts up to greater than .7 - whereas the other two sensors appear to have constant voltage of .64. (did I just answer my own question?)
Thank you in advance.
Chris H.



June ish
Calc Load Value 44.71%
Coolant Temp 176 F
Short term fuel % trim - Bank 1 -1.56%
Long term - Bank 1 46.09%
Short term fuel % trim - Bank 2 -2.34%
Long term - Bank 2 50%
RPM 3001
Speed 48
Intake Air temp 69F

July ish
Calc Load Value 47.06%
Coolant Temp 178 F
Short term fuel % trim - Bank 1 .78%
Long term - Bank 1 32.81%
Short term fuel % trim - Bank 2 2.34%
Long term - Bank 2 32.81%
RPM 2900
Speed 47
Intake Air temp 35.6F

August 25, 2013
Calc Load Value 32.94%
Coolant Temp 181 F
Short term fuel % trim - Bank 1 .78%
Long term - Bank 1 48.44%
Short term fuel % trim - Bank 2 -1.56%
Long term - Bank 2 52.34%
RPM 3261
Speed 55
Intake Air temp 109F

chazen

Hoping that someone with knowledge of Freeze Frame data can take a look at the three data sets I put up and help me with some diagnostic expertise. Someone out there has that skill set .....
Starting to think you don't like folks from Colorado ....
Thanks,
Chris

salimshah

Nah, this board dislikes people from all places equally. NOT

Maybe Lexmex can give you pointers.

Salim

Baetke

Your Air/Fuel sensor and O2 sensor voltages are normal. In any case, the O2 voltage(Sensor 2) has nothing to do with fuel trim, it is used to determine catalytic converter efficiency.

Your freeze frame data is showing that both banks are running extremely lean and the computer is at the limit (50%) of its ability to adjust for it. Since both banks are running lean, I would look for an air leak in the induction system which is common to both. Check everything between the MAF sensor and the intake manifold. Remove the intake bellows and inspect it carefully for cracks while flexing it. Try spraying carb cleaner on the joints while the car is idling and listening for changes in rpm. You might also use a piece of vinyl hose as a "stethoscope". Use about a 1/4" ID hose with one end in your ear and move the other end around the induction system listening for hissing sounds.

Check the operation of the MAF sensor.
At idle the MAF output should read between 3.3 and 4.7 g/sec.
At 2500 rpm (no load) the MAF output should read between 10.4 and 15.4 g/sec.

Finally, you might have low fuel pressure. Unfortunately, I don't know an easy way to check this. Anyone?

Baetke

chazen

Update: Followed Baetke's direction and thoroughly looked for pinhole leaks in the induction system - disassembled and reassembled. No cracks pinholes found.

Thoroughly re-cleaned MAF focusing on the two wires up in the sensor housing - really got after them, spray, soak, shake, repeat.

Reset CEL, nothing showing at this point 5 days in .... hoping for the best.

Thanks for your support.

Chris

Baetke

How do your fuel trim numbers look now?