[joefrontier2]

I'd like to know if anyone has replaced theirs.

Problem-MPG are still too low more than normal.
Check - Service manual says that if there is a big drop in MPG you should check the TPS position and the gap (see picture). I went to check it after the truck warmed up and it still was not warm enough for the plunger to push the gap closed. Adjusting my TPS is my goal but I cannot do this when the thermal plunger will not open all the way.


The plunger is located in the throttle body and senses coolant temp. When it gets hot the plunger moves forward and allows the truck to idle at a lower throttle.

My plan - I am going to breakdown and get a OBDII scanner so that I can easily measure coolant temp to make sure that the coolant temp is where it's suppose to be to open the plunger. If the plunger is malfunctioning I will have to replace it. Courtesy has the part for 120.00$ WOW! That's a lot of $$$. Maybe cheaper to find a whole new throttle body off ebay.

This is a picture of the space gap when the truck is cold. When the truck warms up the gap should close. Mine closed a little bit but not all the way

There are two marks on the fast idle cam (hard to see) the first mark is for cold and the second is for when the truck is warmed up and running correctly. The plunger is located in the throttle body and senses coolant temp.

 

[joefrontier2]

Well from what I gathered for just tinkering with the throttle body is that I think the adjustment screw assembly on the Fast Idle Cam was bent. Not sure how in the world it would have gotten bent, possibly from the factory or by the spring binding and not allowing the rotation.

After bending it back and adjusting the screw it seems to work better. I still need to make adjustments to the TPS as well.

 

[joefrontier2]

Just a follow up on this in case someone is having the same issue.

The truck when warmed should have an RPM range of around 500 when in drive. And a 700-800 range in park. The plunger should push the fist idle cam to the "hot" setting when truck is warm. The truck temp gauge does not need to be a 180 degrees to have the fast idle cam set to hot. So you should see the fast idle cam set to hot before the gauge in the truck is set to around 180.


The truck runs quiet now. Even with my Nismo exhaust it's quiet in the cab. I'm hoping to see better MPG running around town now.

Setting the TPS manually is a pain and I need to still set it accurately and then reset the TPS learned values.

 

[joshsill]

I'm interested in what you are doing with the TPS but I'm still a little confused. Would you get increased MPG because you are not idling as high? What happens when the gap is completely closed like it should be?

I read in the manual that if you disconnect the MAF sensor start it up.....yada yada, that it resets the "learning mode". Is that the same learning mode for the TPS as it is for the A/F ratio that the manual is talking about? Sorry for all the questions but after replacing the two upstream O2 sensors (which were reading bad values) and the spark plugs, I am still getting the same MPG, which I find frustrating because I would think it would have increased at least a little. I'm thinking maybe I need to reset "learning mode" or something.

 

[johnbia]

I have a 2004 frontier quad cab since new. Lately I've had a sticking throttle. When warm (bout an hour of driving) from a standstill, my gas pedal won't move. The issue is not with the cable or pedal but at the throttle itself. It doesn't budge until u break it free by jamming on the gas pedal. it usually does this for about 15-20 minutes and then stops and acts normally. Any ideas what the problem could be? Is this a throttle body issue ?

 

[joshsill]

Any updates on if you are seeing any improvements, joefrontier?

 

[diexodos]

JoeFrontier, the plunger seems to be stuck in the hot position. It is in the forward position pushing against the adjusting screw on the fast idle cam. The adjusting screw is bend like in your picture.

It seems that I have two issues. 1. Plunger is not moving (although truck idles fine and MPG is consistent around 20 MPG) 2. Adjusting screw is bend. I sprayed a little greese and penetrating oil on the plunger this morning and it may assist to get it unstuck.

Also, the plunger had a greenish color and most likely leaking antifreeze. Studum suggested that this may the cuase of leaking antifreeze into the intake. The last two weeks I have lost around 10-15 ounches of antifreeze.

I wonder if it is time to replace the thermo element. Any suggestions if it is needed and how to do it? Thanks.

 

[studum]

I think you misunderstood. I did not say or try to imply that the plunger can case an internal leak. All I was trying to say to you is that if you're seeing coolant in that area that this is where the leak will likely be coming from. I was trying to help you find an external leak that you couldn't locate and suggested that you look in this area.

I also said that even if you're seeing this that I can't gaurantee it's your only problem, as I don't believe that this will cause an internal leak and I don't think it can cause overheating. Take that with a grain of salt, because I'm not a pro and don't know for sure.

If you're unsure take it to a mechanic. It will cost you a bit but it's better to get it diagnosed and fixed properly than throwing money at it and guessing.

 

[diexodos]

Studum. Sorry for the misunderstanding. Uploaded a picture of the plunger from Courtesy Nissan. Plunger has an o-ring which can dry up and leak over time. I can see that an issue with the plunger will create external leaks only.
Since the plunger in my truck is stack in the hot position and the screw is bend, the o-ring is compressed against the body of the plunger and it leaks. I will straighten the screw and push back the plunger with a needle nose plier.
Studum, I enjoy solving mechanical issues and I dont trust mechanics that I don't know them personally.
My truck does not overheat unless coolant drops very low.
Will keep on searching for answers............
Thanks.

 

[joefrontier2]

If you are seeing green around it then you should look for a leak (if possible). All of the piping is internal so I see how it would be getting into the intake.

Also, the plunger needs to go in an out freely and you can detect this by the marks I made in the picture. If it's not moving then I would say 100% go get a new one. I haven't replaced mine yet but I know it's just attached with a screw (however, getting to the screw maybe tricky).

The plungers only purpose is to open the butter fly valve just a bit on cold start ups so to give you a faster idle. If it stays open then anytime you are sitting at a stop light or a stop sign you running the motor at a faster idle and just wasting gas (though it may not be a lot).

The screw adjust bracket bends so bending it back allows for the truck to idle at cold temps where it needs to be.

 

[diexodos]

Joefrontier2. Best case scenario is the plunger is stuck and it can be loosened and pushed back. If it does not push back, I will bite the bullet and pay $126 for a plunger. Such a rip-off having to pay 126 for such a low tech part.

There are two coolant lines that travel to the plunger location. I dont feel any moisture underneath them. If I was 100% certain that the leak is internal to the throttle body and a new plunger will not repair the leak, I would have eliminated those two coolant lines by re-routing the coolant piping at the back of the intake manifold. I wonder if anyone has done that.

 

[diexodos]

The plunger is pushed all the way out. Let the engine cool down for at least three hours and tried to push the cylindrical part of the plunger back. No chance. It is not moving. It is frozen. I wonder if it is possible to loose 10 ounches of antifreeze every 2-3 weeks from the plunger. Took some pictures but camera resolution is higher than what we are allowed to attach..
I am debating if I should replace this part or get a new throttle from ebay for about $100. What do you guys think?

 

[redv6]

is it possible to have the pictures uploaded back to this thread? the pictures would clear up some of the confusion. as i believe I'm having the same issue. in the next few weeks i plan on checking timing, idle, and the cam. because my MPG has gone down a lot recently.

 

[speedfoos]

Mine kept leaking so I pulled the IM off and bypassed the coolant lines that ran to it and also disconnected the spring at the throttle body spacer. No more leaks, no more potentially failing part messing with my idle.

 

[stapler]

I was doing my intake gaskets and came across the same bendy tab/ failed o-ring issue. I didn't have an issue with the idle, but the previous owner may have had it adjusted. I won't know if that fixes the leak until all my stupid under manifold hoses get delivered. Since that gives me plenty of time I'm thinking of welding a little gusset on the tab. Seems like a pretty poor design all the way around.

I don't know what pictures were in the thread, but I hope these help for future reference.

If anybody has trouble reconnecting the spring like I did. I ended up just using a braided steel cable to pull it into position.

 

[kevinjohnson3216]

Could this cause internal leaks into the intake manifold???

 

[stapler]

I don't think so, It really only pushes that little piston and ads a bit of throttle. Even if it leaks there it won't get sucked into the throttle body unless you have a huge hole in the tube that goes between that and the air filter (which would cause idle problems). The gaskets on the lower intake are known to leak both in to the valley and into the intake though.

 

[redv6]

I don't think so, It really only pushes that little piston and ads a bit of throttle. Even if it leaks there it won't get sucked into the throttle body unless you have a huge hole in the tube that goes between that and the air filter (which would cause idle problems). The gaskets on the lower intake are known to leak both in to the valley and into the intake though.

when replacing intake gaskets use the Factory nissan gaskets. other gaskets in here like to leak for some reason. a shop that rebuilt my heads and did head gaskets awhile ago went through several different sets of gaskets before finally using the nissan gasket i gave them in the intakes. the torque sequence is a real PITA too but make sure its followed or you will get leaks, weather or not its a nissan gasket or something else. you could possible over the gaskets with some red RTV to if you wanted. on both sides. just a skim coat. don't get the cheap crap.

 

[kevinjohnson3216]

I don't think so, It really only pushes that little piston and ads a bit of throttle. Even if it leaks there it won't get sucked into the throttle body unless you have a huge hole in the tube that goes between that and the air filter (which would cause idle problems). The gaskets on the lower intake are known to leak both in to the valley and into the intake though.

I'm about to get into the valley next weekend... Can you elaborate on this? I don't understand what you mean by the lower intake gaskets leaking, do you mean a vacuum leak? I'm doing all 6 injectors, knock sensor and lower intake gasket. Everything above that is good. Do the fuel rails have special o rings of their own other than the rings that came already installed on my new intake? Kind of off topic. Anything I should be aware of when doing this job? I know the vacuum and coolant lines against the firewall are going to be hard to get off. Please give me whatever feedback you can, thanks.

when replacing intake gaskets use the Factory nissan gaskets. other gaskets in here like to leak for some reason. a shop that rebuilt my heads and did head gaskets awhile ago went through several different sets of gaskets before finally using the nissan gasket i gave them in the intakes. the torque sequence is a real PITA too but make sure its followed or you will get leaks, weather or not its a nissan gasket or something else. you could possible over the gaskets with some red RTV to if you wanted. on both sides. just a skim coat. don't get the cheap crap.

Coat which gaskets with silicone, the upper and lower intake manifold gaskets? Please see my above post too, I want this job to go smooth. Thanks!

I'm also changing tps, do I need to do the feeler gauge and resistance method or is there a better way to set up my new tps? Thanks

 

[stapler]

The lower gaskets (one for each bank) seal both air and water passages, so it's possible for one to leak into the other as well as into the valley. If you follow the instructions for tightening and use oem gaskets you should be fine.

The Injectors do have rubber seats they sit in which may be the rings that came with your intake, also you can order the other outer rubber parts of the injector as long as you are at it (3rd party). I also did the fuel regulator and all the intake hoses as long as it was all off. The only part that didn't go smoothly for me is all of the rear water connections on the back of the intake. Just too little room for my fat fingers to maneuver easily.