albino Posted February 5, 2014 Share Posted February 5, 2014 About two weeks ago my check engine light came on on the highway and I took it to the store and it had two oxygen sensor codes. A few days ago I went back to get the SES checked again to make sure that I ordered the right replacement sensors. This time both oxygen sensor codes were gone and a TPS code was present. At this point the truck was driving normally and I took it home to look into it. That night I went to start it up and when I put it in reverse it stalled out. I have this problem sometimes when it is cold so I didn't think twice and started it back up. This time it stumbled for a few seconds and died. Now it stalls every time I start it. Is this sensor something that might just need a cleaning or should I just replace it altogether? Unfortunately I need my truck this weekend so time is not on my side. Link to comment Share on other sites More sharing options...
silverton Posted February 5, 2014 Share Posted February 5, 2014 the TPS isn't something that can be cleaned. Sometimes you can get a code from other components being messed up. I recommend replacing the O2 sensors, resetting the codes and wait to see if it comes back. Link to comment Share on other sites More sharing options...
CNAM Posted February 5, 2014 Share Posted February 5, 2014 Timing position sensor. Fairly cheap and very easy to replace. Or throttle position sensor. I had to change both of mine as well as the mass air flow sensor. My truck world start and run ok. But when I'd accelerate it would bounce off the rev limiter about 4-5 times before shifting into 2nd gear. (Auto trans). Especially when cold and usually only at first start up and run of the day. Don't think it can be cleaned. Link to comment Share on other sites More sharing options...
albino Posted February 6, 2014 Author Share Posted February 6, 2014 It is the throttle position sensor. I will go to the junkyard and pull a sensor and see if I can get it started up with that. I will probably pull some old O2 sensors from the junkyard too just to see if that helps. I wouldn't think that the O2 sensors would have anything to do with it though seeing as I was driving with the O2 codes for a while without problem. It was the forward and rear sensors on the passenger side and I am assuming that the engine should be fine running off the sensors on the drivers side. I'll get the new O2 sensors as soon as the codes come back and I can confirm they were passenger side sensors. Link to comment Share on other sites More sharing options...
silverton Posted February 6, 2014 Share Posted February 6, 2014 Assuming is bad. The O2 sensors are one of the pivotal components to ensuring that your engine is running properly. Your truck maye has 3, but probably 4 O2 sensors being a V6 and in the correct configuration. You have a primary O2 sensor for both left and right banks. These are the ones that ensure the air/fuel mixture is proper. When a primary O2 is bad it is no longer measuring the amount of oxygen in the exhaust stream and can not adjust fuel trims properly. With one working O2 sensor, and one not working O2 sensor the ECU could think that the amount of oxygen going in to each bank is wrong and might think the throttle position sensor is not telling the ECU the proper information. Then you have the secondary O2 sensors which on some vehicles work with the primary to ensure that the fuel trims are at peak efficiency. But in most cases they just monitor the condition of the catalytic converters. Link to comment Share on other sites More sharing options...
albino Posted February 6, 2014 Author Share Posted February 6, 2014 Yeah I am aware of the purpose of O2 sensors and this truck has 4 O2 sensors, one upstream and downstream on each side. I am assuming that when Nissan designed the ECU logic they made it so that it could run off only one upstream and downstream sensor so that the engine wouldn't go into limp mode when a single upstream sensor was lost. I am basing this assumption off of engine control logic I have worked on in the past. Honestly I would hope the truck could run on just one upstream O2 sensor as the downstream sensors are usually only needed to check the operation of the cats. Typically I do not make assumptions when working on my truck but since I have experience with engine control I am confident in this one. I am going to replace the O2 sensors soon but the TPS sensor has moved ahead of them on the list and I still need to confirm which O2 sensors are on the way out which is much easier to do with a working truck. Link to comment Share on other sites More sharing options...
albino Posted February 11, 2014 Author Share Posted February 11, 2014 Does it make sense that the TPS sensor would be causing the vehicle to stall immediately upon start up every time? From what I have read usually the TPS is responsible for high and irregular idle with the occasional stall. I replaced the sensor today and the truck is still stalling immediately after starting. I have not had time to adjust the sensor rotation as it has been raining here but I will adjust it tomorrow morning weather permitting. I am not confident that this will fix the problem though. I am hoping to get the truck up and running tomorrow since it is supposed to snow here and I would like to be able to get around. My plan of action is to check the connections to the TPS and then try adjusting the position of the TPS. If that doesn't work than my next thought would be that the engine is not getting fuel. Link to comment Share on other sites More sharing options...
silverton Posted February 11, 2014 Share Posted February 11, 2014 (edited) Aren't O2 sensors supposed to make sure the engine is getting the proper amount of fuel? Edited February 11, 2014 by silverton Link to comment Share on other sites More sharing options...
albino Posted February 11, 2014 Author Share Posted February 11, 2014 The computer uses the O2 sensors to run closed loop and get the optimal fuel/air ratio. With bad O2 sensors the car will still run but the computer will be running open loop and will be using the airflow data to try and predict the amount of fuel it needs to supply. It will not know if this is the optimal fuel/air ratio because it doesn't have the O2 emissions data but it will still run at reduced efficiency. Link to comment Share on other sites More sharing options...
Rebelord Posted February 11, 2014 Share Posted February 11, 2014 TPS may need to be set. Cant tell from phone. But if its a 3.3 should be a voltage set. 3.5 have a tps relearn procedure. FSM has it all. Ah... You said its been raining. Try to get it set and see if it still stalls. Side note Maf clean and its connections? Sent from my Moto X Link to comment Share on other sites More sharing options...
fixinto Posted February 13, 2014 Share Posted February 13, 2014 does it stall only in gear? when its cold, or after it warms up. I know you can unplug the TPS and it will fire right up because thats how u set timing or w/e. try unplugging your maf. see if it will idle. if so. clean your maf. unplug ur tps and see if it idles as well. and x2 about closed and open loop. i had an O2 bad and it just ran in closed loop and got crappy mpg until i could replace it. best of luck to ya Link to comment Share on other sites More sharing options...
albino Posted February 13, 2014 Author Share Posted February 13, 2014 Thanks, I haven't been able to catch a break with the weather around here this week and it has been raining and snowing every day. Hopefully tomorrow it will clear up and I will have time to do some troubleshooting. It initially stalled the first time when I first started it up and put it in reverse. Then I tried starting it up a few more times and it stalled while still in park. Each time I started it up it stalled a little sooner. Now it cranks but won't catch. I am starting to think that maybe I blew a fuse on the fuel pump or the relay is bad. The symptoms are right for no fuel getting to the engine. Maybe the TPS sensor was something else that just happened at the same time. On the bright side I realized I was missing the EC section to the fsm and now that I have found it I have the knowledge to test all these things. Link to comment Share on other sites More sharing options...
albino Posted February 14, 2014 Author Share Posted February 14, 2014 Well it turns out the problem was with the fuel system but it wasn't the fuel pumps fault. I had parked downhill without a lot of gas in the tank and the pump wasn't able to get any fuel to it. A few gallons later it was good to go and the SES light was off thanks to the new TPS sensor. I took it for a spin and it drove normal but I still need to set the TPS sensor correctly. The method in the fsm for setting it is slightly confusing. Link to comment Share on other sites More sharing options...
albino Posted February 16, 2014 Author Share Posted February 16, 2014 I am trying to use the Haynes procedure for setting the TPS closed position sensor but I ran into an unexpected problem. The procedure involves inserting a 0.012" feeler gauge in between the throttle lever and stop screw. At this point, the TPS sensor should have continuity across the top two terminals. Then insert a 0.016" feeler gauge and there should not be continuity. The sensor is supposed to be adjusted until these conditions are met. The problem I am having is that my throttle lever never rests on the stop screw and it is always greater than 0.016" from the stop screw so of course I get the same results for both feeler gauges because they are not actually moving the throttle. Here is a picture where you can see the throttle lever, stop screw, and feeler guage: I believe the reason why my throttle lever never rests on the stop screw is circled in red. This piston does not seem to move regardless of if the engine is hot/cold etc.... What is this piston? Here is another view of it again circled in red: I have looked through the fsm but haven't been able to find what this is. I am guessing it is stuck and that is my problem but I have not dealt with this before and am open to any other suggestions. Thanks in advance. Link to comment Share on other sites More sharing options...
Rebelord Posted February 16, 2014 Share Posted February 16, 2014 On phone but looks like idle air control. Sent from my Moto X Link to comment Share on other sites More sharing options...
fixinto Posted February 18, 2014 Share Posted February 18, 2014 the fast idle cam, i just unscrewed mine till it didnt rest on the thermo element because it wasnt functioning. so disconnect bam. good to go. hope this helped Link to comment Share on other sites More sharing options...
fixinto Posted February 18, 2014 Share Posted February 18, 2014 or u can wait till your truck is warmed up all the way and everything should be correct, if not and it is functional, try adjusting it. Link to comment Share on other sites More sharing options...
albino Posted February 19, 2014 Author Share Posted February 19, 2014 The truck was warmed up all the way when I was testing it before. I'll have to look into how to adjust/check the fast idle cam. It didn't look like it was moving at all as the truck warmed up so I think it may be shot. Thanks for the help. Link to comment Share on other sites More sharing options...
fixinto Posted February 19, 2014 Share Posted February 19, 2014 np at all Link to comment Share on other sites More sharing options...
fixinto Posted February 19, 2014 Share Posted February 19, 2014 ya that would probably be the way to go. last i priced the thermo element, it was around 150, plus u have to take off the upper intake to get to it. so not really worth it. even with mine unhooked, when i first fire up even on cold days it fires right up and after a second or two the ecu adjust the idle to about 1200 till it warms up. so no biggy Link to comment Share on other sites More sharing options...
albino Posted February 19, 2014 Author Share Posted February 19, 2014 Gotcha, I'll put it on the list of things to do that require the intake manifold to be removed. One of these weekends I'll get around to it. Link to comment Share on other sites More sharing options...
fixinto Posted March 28, 2014 Share Posted March 28, 2014 i dont know if i told you this or not but where u were trying to put the feeler gauge was the wrong spot. anyways, did u get it lined out? hope so. I have a link to a crappy video i made about how to set your tps under the 96 pathfinder forum label of post " i killed my pathy" but i really didnt, it was a lot of work basically to just freshen up the lifters and change the timing belt, drive belts, rad hoses, water pump and thermostat. lol.... anyways hope all is well with ur pathy. Link to comment Share on other sites More sharing options...
albino Posted May 5, 2014 Author Share Posted May 5, 2014 Nah I didn't realize that was the wrong spot ha... where is it supposed to go? The manual I was looking at didn't exactly make it clear. Also do you have any idea what the part # is for the thermo-element? I am having a hard time locating it. Link to comment Share on other sites More sharing options...
fixinto Posted May 6, 2014 Share Posted May 6, 2014 Link to comment Share on other sites More sharing options...
albino Posted May 6, 2014 Author Share Posted May 6, 2014 Thanks Link to comment Share on other sites More sharing options...
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