QuestionQUESTION:
Hey Von Sudderth, I asked you a question before about my Pathfinder. I have replaced thus far: fuel filter,distributor cap,rotor, wires, plugs, ignition coil, , coolant temperature sensor. Our mechanic spent 6 hours on it and thought it was the o2 sensor. He checked the fuel pressure, timing, cleaned the MAF. Unfortunately it is still doing the same thing, runs great until warmed up, then it starts running rough, but idles good and at low rpms manages to run but roughly,will not go into high rpms and when I try it slightly backfires, but it wont stall. If I spray the motor with the hose, it will run fine again sooner than if i just let it to sit. I thought for sure it was the coolant sensor. Im in dire need of advice, as im running out of options, it has gotten quite expensive. Thanks Robin.
ANSWER: Robin,
Have the technician backprobe the mass airflow sensor to make sure it is not blown. For some reason Nissan air meters can fail without throwing a code. Also, have the converter checked to see if it is melted internally. If the car has a plugged converter it will do as you describe. The technician can test for backpressure with a compression gauge on the exhaust, where the oxygen sensor screws in. Over a pound and a half of backpressure means the converter needs to be replaced.
---------- FOLLOW-UP ----------
QUESTION: hey von sudderth. our cat converter was definately plugged and replaced, along with the MAF. We still are faced with the problem. We are focused on the device that is connected from the head of our intake manifold, it has three hoses, including the one from the intake manifold that reaches to the opposite side of the engine, right in front of the fuel filter. It gets very very hot, and when i run the hose on it, and it cools down our car runs good again,proportionately to how long weve ran it. Our mechanic did not know what it was, he said it was some aftermarket device. Our pathfinder used to run on Natural Gas. The back is a brass plate with a small hole that you can definately feel a diaphragm. After having done almost everything we can do, we are starting to think this is the problem. It also has an electrical connection, a small squarish solenoid or something. Stumped?(our camera is broken, but we will borrow one if need be) Thanks Robin.
AnswerRobin,
The device you speak of is the diverter valve that allows the car to run on Liquid Petroleum Gas (LPG) and not gasoline. If it is leaning out the mix the car will run hot. I would either find a place that does the LPG conversion or servicing or I would just remove it if you are not going to use LPG. But, if you vehicle is already equipped I would try and get it fixed so you have a choice of which you want to run.
