Pressure in cooling system
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osageorange4
- Posts: 27
- Joined: Sun Apr 12, 2015 7:11 pm
- Car: infiniti qx 4 2002
Pressure in cooling system
I have a 2002 qx4 that I have been having a P0300 code I have been chasing for months. In the process I just noticed that there never seems to be any pressure built in the cooling system. Neither hose that feeds to the radiator ever builds pressure. I can even take the cap off the radiator after its been running and there is no pressure. The temp gauge in the car never shows it overheating and the hot air works. Usually on other cars I have worked on if there is bad flow the heat does not work. Has anyone ever seen this condition before. I also have a MAF sensor that I have been looking at. According to the manual it should have around 1.6 volts. Mine always shows 5 volts . I cant understand how I can get more volts than I am suppose to. It is a 4 wire MAF
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rgk
- Posts: 588
- Joined: Tue Dec 23, 2014 4:48 am
- Car: 02 Pathfinder LE 3.5 auto 4x4
- Location: Indiana Dunes National Park
Re: Pressure in cooling system
Are you losing any coolant? My first thought is a random misfire due to a crack or warpage in the head that is letting in air.
You can have the system pressure checked at a shop, or just buy your own radiator pump gauge.
Is your bleeder cap intact and tightened? Is your radiator cap in good shape?
You can have the system pressure checked at a shop, or just buy your own radiator pump gauge.
Is your bleeder cap intact and tightened? Is your radiator cap in good shape?
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osageorange4
- Posts: 27
- Joined: Sun Apr 12, 2015 7:11 pm
- Car: infiniti qx 4 2002
Re: Pressure in cooling system
I am not loosing any coolant at all. I dont see any coolant in the oil either which is something I have heard is hard to detect. I did take the exhaust pipes off behind the first cats today. I noticed the drivers side sounded like a open header but the passenger side made no noise whatsoever. Now I am wondering if my cat is plugged up and wont let the pressure out causing the mis fires
Re: Pressure in cooling system
Yep, I would definitely pull the cat and check it since you are in there. Definitely seems odd.
As far as the MAF, page EC-182 of the FSM has wire colors and voltages. There is a wiring diagram on EC-185. 5 volts is the voltage suppied to the MAF on pink/black. Other wires are as noted in the table. Looks like you need to check Orange.
It sounds like your cooling system is working well other than the pressure issue. Since you are not losing coolant, your head gaskets, hoses, etc. are fine. I think a new radiator cap may fix you up there.
As far as the MAF, page EC-182 of the FSM has wire colors and voltages. There is a wiring diagram on EC-185. 5 volts is the voltage suppied to the MAF on pink/black. Other wires are as noted in the table. Looks like you need to check Orange.
It sounds like your cooling system is working well other than the pressure issue. Since you are not losing coolant, your head gaskets, hoses, etc. are fine. I think a new radiator cap may fix you up there.