EGR,Evap, and coolant codes on my 97 Path

[Davis4ChristNY]

Ok so when I got the vehicle in 2011 I knew there were codes on the vehicle. One at that point was for a knock sensor... That had been previously replaced 2 times because I guess Nissan says there is an issue with the system and a service bulletin has gone out to nissan techs... With the knock sensor code at that time was the egr and evap codes as well. The knock has sense gone off, yet the egr and evap codes remain. I do have two hoses near the gas tank and rear canister that need replacing as they rotted out. Could they be the cause of the EGR or Evap codes? I know Nissan has recognized an issue in this system and errors are registering where there is no problem.

Also about 2 months ago the engine started to idle high in neutral or park, and runs high in drive as well... Thought it might be throttle body, or timing with a tune up needed. It has not been done in a long time as when I did it, the plugs were rusted... The throttle body looked fairly clean and operating correctly. Went to Autozone and had it tested and it threw a code for a thermostat error, a coolant sensor error, etc... So I replaced the thermostat, and it seemed to have fixed the problem, that is until the vehicle sat for about 5 hours, then I drove her home, and the same issue happened all over again. I saw somewhere that air bubbles in the radiator might cause similar issues, could this be the cause of that code and why the ecu is telling the vehicle to run hot? I am getting sufficient heat from the fan, and the temp gauge reads normal. However I did notice a thick kinda film/glaze of orangeish stuff on the top of the coolant while looking in the radiator...

Perhaps the issues I just described are related? And it just took time for the ecu to start running the vehicle hot like it is? I doubt it as it does not make sense to me. I am able to do most repairs myself, just diagnosing I need some help, especially when Nissan admits there are code errors that are causing other codes to be thrown out at the testers... Please help!!!!

[Davis4ChristNY]

And I did put some water in the radiator after replacing thermostat... I have an overflow reservoir that is shattered and needs to be replaced, but if it is an air bubble in the system, if I just clamped the hose that allows for the overflow to run to the reservoir, I should be fine though right?

[Towncivilian]

Could you post a list of all current engine codes?

Inspect the radiator cap according to this TSB and replace with a new OEM one if required.

[Davis4ChristNY]

Thank you I will check it out. Do you think this applies to the 97 though? And would this cause the engine to run at higher rpm's in neutral and park, and burn gas? Also would this throw the same codes? I will take a look at the receipt if I have it and post soon. Going to take a look at the cap now!!! This is why I came to this site. Way easier than taking it to the service department, and cheaper too... Friendly people unite! You are a blessing!!!! Seriously if this is the problem I will thank God for you.

[Towncivilian]

Yes, radiator cap inspection procedure should be the same for your '97.

I'm not sure what could be causing your high idle and excessive fuel consumption. I might have a better clue when you post a list of all current engine codes.

How many miles are on your Pathfinder? If it's over 105k miles, do you know if the spark plugs and timing belt were replaced around that time?

[Davis4ChristNY]

I just did a tune up on the thing last week. And yes its over 150,000 but the problem was happening before I did the tune up, that is why I did the tune up... The timing belt, has not been replaced. And I just went out and checked it out. The cap is almost brand new and is not the same style as that recall photo. What I did notice though while reving the engine with the throttle cable it sticking, which it has done sometimes. I then noticed a plate that the throttle cable mount rests on, and that is on a pivot under the intake to the throttle body. I bent that plate out and the idle dropped to below 1,000 rpm's in park. Is that connected to the timing of the vehicle? And if I bent it out that means the throttle cable mount drops lower causing the lower rpm's, could the timing belt have a connection to why that plate is not sitting in its rightful place, thus causing the throttle body to be open?

[Towncivilian]

Adjust the throttle and cruise wires according to the instructions on page FE-3 and page EL-181 of the factory service manual, respectively. This will eliminate any slack or overtightening of the cables, which can potentially cause the throttle body plate to stay open at idle.

Could you provide a photo of the pivot point you speak of? It's a little difficult for me to visualize, especially never having worked on a VG33E in person. Have you cleaned the throttle body? There could be a significant amount of carbon build up preventing the plate from moving freely.

[Davis4ChristNY]

Ok I can not provide a photo now, but I can say that the throttle cable comes through a cradled piece of metal that is like a quarter of a moon ish... Then there is a pin that sticks off of that with a bearing that spins. That bearing rests upon a plate that has a pivot point with a large spring on the outside portion. I am assuming that is connected in some way to the throttle body and if the body is dirty it does not allow the plate inside the throttle body to close, in turn not allowing the throttle cable to rest in its rightful place. Guess I should just clean the throttle body and see if that helps... It really looked pretty clean when I checked it the other day, and seemed to be operating fine. But perhaps my fine is not correct... Hahahaha.

[Towncivilian]

There may be carbon build up on the back side of the plate.

The component you speak of is pictured in this photo, correct?

[Davis4ChristNY]

OK see that spring under the accelerator? Underneath the vacuum hose? I bent the plate that sticks up, and instantly the idle went down...

[Slumpert]

The evap system in our 97's is designed to deal with fuel vapors, but seemingly over filling the gas tank will allow fuel itself to enter the evap lines and canister and that messes it up over time. There is a "foam" filter that holds the charcol in and that foam gets eaten by the liguid gas.

[Davis4ChristNY]

Slumpert, that is what I thought. So in theory, if one of or both of these lines to the canister from the tank, and or to the engine is rotted it might trip the code, correct? And am I wrong in declaring that perhaps because there is a fault in this system, it is reading and egr error as well, per the service bulletin that mentioned the system throws out codes that are in error, and not needing repair? Obviously I need to fix them, and when I can get under this thing with some tools to cut the existing hoses off of there respected metal lines, I will replace them. But I am wondering if I should bother with trying to figure out the EGR code issue, because before inspecting this vehicle I cleared the codes and drove the vehicle over 500 miles before the ecu was ready to pass, then not 30 miles after inspection the light came back on... So I dont want that to be the case and then find out I should have tried to fix the egr issue... Being if there is one. You know what I mean?

[Slumpert]

I suggest going to the junkyard and pulling the canister and all hoses off a donor.. Try to find a 97-99 as I am pretty sure one of the lines going to the 2000 was a bit bigger than ours. Once you pull the canister, shake it and if you hear it rattle go look for another one. I was only charged $12 for the canister and all the hoses connected to it..

EGR valves are completely different usually a tell-tale sign is if your "driving" at just over idle say 10-15 mph and the vehicle seems to surge randomly. I would trust that code and check the vacuum line going to the valve before just replacing it.

[Davis4ChristNY]

Right. I had a technician give me a diagnostic tip on the egr valve. The diaphram being held open caused the vehicle to stall, and there was full movement in the diaphram. Is he full of crap in his diagnoses? Or like I said could the egr code be tripped because of the system issue the Nissan has sent out service bulletins about? I saw it with my own eyes, although do not have a copy on me. But they admit that the system in this year model and some others I believe have connection issues or something is wired wrong, or whatever, but it the bulletin said the ecu will throw codes out that are not supposed to be. And I do believe that the knock sensor, temp sensor, and the egr valve were included in a list of codes that could potentially be registering on the ecu, but not in need of repair... The egr valve is behind the engine on the driver side correct? I know it is completely different, but that bulletin has me thinking since I did the quick diagnoses a tech told me to do to test if the egr valve is working correctly, its just the error of the ecu sending out codes it shouldn't be. And I know that the hoses are rotted out, I have known to test the canister but have not done so because I have not been able to get underneath her. I have limited tools, as my adult life started late, cause I was a moron when I was young... Anyways, the vehicle does not surge, the rpm's were just way to high for any position of the transmission, drive, neutral park.... And there was a little bit of play in the cruise and throttle cables, but I tried to tighten them and they would not. Is there supposed to be absolutely no play in those cables? And would this cause the accelerator peddle to be stuck, requiring me to literally kick it to be able to give the vehicle gas???