I have been reading many discussions regarding these problems and much points to the plenum but I wanted to run it past to find out your thoughts.
Vehicle = 2002 Deville
Unknown maintenance history. Check Engine light on for last two (at least) years (appx 8000 miles). Driven by 80+ year old man that should not have been driving anyway. I inherited it after his death.
I retrieved the codes thanks to the info found here.
B0429 = Aux rear temp air door.
I understand this is a common code and not worth messing with.
B1004 = Keep alive memory.
B1327 = Device Power Circuit low.
May have been triggered by the battery??? Had to charge battery at one point when there was not enough power to turn over starter motor.
I guess none of these really means much and likely has nothing to do with engine performance but I wanted you all to have all the data I have.
Now the interesting codes:
P0101 = Mass air flow sensor.
From what I have read on these forums the sensor may be bad but is not as likely as if there is a vacuum leak after the sensor.
P0171 = Fuel Trim Lean
P0174 = Fuel Trim Lean
P0300 = Engine misfire detected
Bad spark plugs? Bad coil? Bad Wires?
P0741 = TCC stuck off
Torque converter problems? No problems shifting noted.
P1189 = Engine oil pressure switch circuit.
When I inherited the car I took it to Tire Kingdom for tires and they checked the oil and found it was very low. Maybe so low that the pressure was below spec at some point and left the code in the computer?
P1860 = TCC PWM solenoid circuit electrical.
The vehicle seems to drive normally at highway speeds. The display on the dash shows average MPG as between 12 and 14 MPG.
After I acquired the car I drove it from Florida to SC with no problems (approximately 6-700 miles).
A couple months later the engine began to idle roughly.
With the transmission in park and the throttle applied, when it gets over 3500 RPMs the engine surges.
With the transmission in "D" and the vehicle stopped the engine idle falls to about 700 RPM and idles roughly... may stall occasionally.
With the vehicle traveling at approximately 30 miles per hour no throttle pressure applied the RPMs and speed gradually increase. Vehicle will not hold low RPMs or stand still while in "D". Speed will not decrease normally when throttle is released.
OK, Guys. I suspect from reading all the threads that I have found that the Intake Plenum may be the culprit. I did not have any carb cleaner to test it so I sprayed WD-40 on the plenum clamp screw with no change in RPM.
What do you all think?