D22 ZD30 Throttle cutting out / Intro

[scottm]

Hi All,

First post... I recently bought a Navara 2002 D22 with 143,000 on the clock. It's my first 4x4 so bit of a learning curve for me, made the purchase so I could get to better camping destinations with my wife and if I'm honest hunting destinations also.

I gave it what I believe to be a full service (engine oil, oil filter, fuel filter, air filter, transmissoin oil, transfer case oil, front diff oil, limited slip diff oil) and then took it away recently. Discovered a few issues but the most annoying (and potentially dangerous) is the throttle cutting out while driving.

It happens at all different speeds - when just starting off, cruising on 100k p/hr or doing 30 around a roundabout. I give it a few pumps on the accelerator peddle and it usually comes back straight away. Sometimes though it takes a while (200 meters) and then kicks back in. What I have noticed is that it is more prevalent on bumpy roads. Very often I can be doing 40-50k p/hr and hit a decent bump and it'll cut out, again a few pumps on the accelerator peddle and it usually comes back.

I don't really know where to start with this. If it was -just- having a hard time getting throttle at all (it usually only has trouble coming on after it has cut out at speed) I'd think the cable was sticking or something similar but for it to be accelerating happily and then cut out I don't really know (don't understand the mechanics of it all).

I'm learning as I go along and quite happy to have a crack and pull things apart / put back together but it'd be awesome to get a pointer in the right direction is somebody has experienced anything similar?

Thanks all in advance, look forward to hanging out on these forums. I have heaps a of questions about mods etc just need to find the right area of the forum to post in. I'm in Sunbury, Victoria would love to know if there is anybody else form the area.

Cheers

Scott

 

[charlie strayarc]

Have a look at the nuetral position switch first.
Use search function to learn all about it.

 

[baitfish]

if your losing all throttle its prob not the neutral position switch i'd lean towards an issue with the throttle position switch mate. Not sure if you know but they use a 0 to 5v signal from the throttle to drive the fuel pump.

If you push the clutch in when you loose throttle response does the ute just go back to idle revs? To me it sounds like a failing TPS or you have a bad connection somewhere between the throttle to ecu or ecu to the fuel pump.

Think the easiest point to start would be the throttle position switch connector. The accelerator pedal has a box like thing on top of it with two connectors, pull them off, check for corrosion and put them back on and see how it goes mate. The actual box is like a variable resistor that takes the 5v in and changes this with resistance. it has a wiper inside the box that moves back and forth with pedal movement. it could be dirty in there but its a sealed unit so probably not as much chance as that being the problem.

 

[tweak'e]

the other common suspect is fuel filter. check its done up tight. also they may have not replaced the o ring on the bottom. that can cause air to be sucked in which can cause the cut out when you go around a corner.

 

[scottm]

if your losing all throttle its prob not the neutral position switch i'd lean towards an issue with the throttle position switch mate. Not sure if you know but they use a 0 to 5v signal from the throttle to drive the fuel pump.

If you push the clutch in when you loose throttle response does the ute just go back to idle revs? To me it sounds like a failing TPS or you have a bad connection somewhere between the throttle to ecu or ecu to the fuel pump.

Think the easiest point to start would be the throttle position switch connector. The accelerator pedal has a box like thing on top of it with two connectors, pull them off, check for corrosion and put them back on and see how it goes mate. The actual box is like a variable resistor that takes the 5v in and changes this with resistance. it has a wiper inside the box that moves back and forth with pedal movement. it could be dirty in there but its a sealed unit so probably not as much chance as that being the problem.

Hi Baitfish,

Thanks so much for taking the time to reply. I didn't know about the 0 to 5v signal thanks for letting me know.

Yes, when I push the clutch in when I lose throttle it does go back to idle revs, in fact that's what it does without clutching in. For instance, was driving on a bumpy dirt road and lost throttle, was tapping accelerator like normal to get it to come back on but it was taking it's time so I put the car in 2nd gear and the car at idle speed was enough to keep us going along until the throttle came back after more tapping of the pedal (probably 500M or so).

I'll check out the connectors inside the box on top of the pedal first thing tomorrow morning (assume this is just inside the cabin in a hard to reach place?).

Thanks again for the pointers will let you know how I go tomorrow.

Cheers,

-Scott

 

[scottm]

the other common suspect is fuel filter. check its done up tight. also they may have not replaced the o ring on the bottom. that can cause air to be sucked in which can cause the cut out when you go around a corner.

Hey tweak'e, I'll double check that tomorrow. I did the service myself (I've had so many crappy experiences in the past with dodgy mechanics I figure I can't do ny worse and with some care I may just do a better job!) so it'll only be me to blame if it is indeed loose!

 

[scottm]

Have a look at the nuetral position switch first.
Use search function to learn all about it.

Thanks Charlie, without reading heaps of threads to work out symptoms etc I just found the thread at http://www.navara.asia/showthread.php?t=4089&highlight=neutral+position+switch which indicates how to test it, so I'll just do that and see.

Cheers again!

 

[Rumpig]

This is a pic of the throttle position sensor on the side of the pedal. There's also a switch for " wide open throttle" and another for "closed throttle". You can't buy the TPS on it's own, Nissan only sell a complete pedal assembly of which i have a spare,

 

[Rumpig]

Try a TPS relearn, warm it up and then leave it idle for a full 10 minutes.

 

[scottm]

TPS relearn could have made it worse?

Try a TPS relearn, warm it up and then leave it idle for a full 10 minutes.

I did a TPS relearn (just let it idle for 10 mins). Is it possible that this could have made the problem worse? I did it one evening and then turned the car off as I had to go out, then the next morning on the way to work I barely got 200 metres down the road before the the throttle would barely work at all and I just had to nurse it back home in 2nd gear and idling. This is the worst I've ever had the problem, but haven't driven it again since (normally it just comes good after a few throttle pumps).

Not sure if the above is just a coincidence or not... Would love to know your opinion.

I've got time today so I'm going to go ahead and start working through the other suggestions made and will post with progress as I go.

 

[Rumpig]

Doing the TPS relearn wouldn't harm it. Your symptons sound similiar to a problem i had, which ended up being the wire from my Tunit chip which taps into the TPS had a short, I replaced that wire and was back to normal.

 

[scottm]

Hard to get to TPS

Hey Rumpig,

Thanks so much for your reply and taking the time to take a photo and post it, really appreciate it and really helpful.

I don't believe I have a Tunit chip but understand it could be a similar problem (but frankly I wouldn't really know) I assume that is an aftermarket chip to enhance performance etc? (I've been looking into the Chip Tuning chip briefly).

Anyway... As baitfish suggested I've tried to take the TPS connectors off but had no luck. They certainly don't come off easily (I feel like I'm going to break the plastic housing if I pull anymore) and I'm really struggling to get a philips head in there to undo the screw and remove the whole piece from the top of pedal. Any tips on how to get to it to check for corrosion etc? It's the most awkward angle, I'm probably attacking it all wrong....

Thanks again for your help...

-Scott

 

[scottm]

Have a look at the nuetral position switch first.
Use search function to learn all about it.

Hi Charlie,

I've followed the instructions over at http://www.navara.asia/showthread.php?t=4089&highlight=neutral+position+switch to test the Neutral Position Switch and it would appear mine is totally stuffed (either that or I'm doing something incorrectly). I start the car, put it in neutral with clutch in and then turn on the heat switch. The revs increase marginally (certainly not to 1200 as suggested in that thread) and do not drop when I put it in any gear (still with clutch in though).

The other stuff I've read on the forum seem to suggest mostly losing power in 3rd/4th (mine does it in all gears) but when it lost power in 4th I pushed the lever to the right and left and it didn't change anything at all (contrary to what other posters have experienced).

For $50 I think I'll probably just replace it but let me know if it sounds like I'm testing it incorrectly.

Cheers,

-Scott

 

[charlie strayarc]

Easiest way to test it if your unsure is unplug it and go for a drive, it wont harm anything, costs nothing and only takes a few minutes.

Have you pumped fuel primer? Does it go hard after 3 pumps or is it still moveable after say 7 or 8? If so air in the fuel line is culprit. Could be filter housing letting in air, split lines, o ring on filter not sealing. you can fit clear hose before and after filter (this is temporary for the test) and prime up filter then run car and check for air bubbles in the clear hose. Bubbles after filter but none before means filter housing etc is to blame. Bubbles before filter indicate hose leak pre filter.

But rule out the nuetral position switch first, it may not be the problem but costs nothing and these switches do strange things to these vehicles.

 

[scottm]

Doing the TPS relearn wouldn't harm it. Your symptons sound similiar to a problem i had, which ended up being the wire from my Tunit chip which taps into the TPS had a short, I replaced that wire and was back to normal.

Hi Rumpig,

So I started looking around for crunched wires etc (this would make sense to me as the problem occurs regularly over bumps which could indicate a wire shorting).

I found that the cruise control is an aftermarket one from Autron. Have attached photos of one of the units. I'll keep investigating and tracing all the wires to see if they are damaged but was thinking - could it be a problem with the actual unit and maybe I should just disconnect it entirely? (assuming I can work out how to return it all to normal.

I ended up being able to get to the TPS by just undoing the bolt on the otherside of the firewall as well as a couple on the inside and the whole pedal came out (I didn't realise it would be that easy). I checked the connectors on the two plugs which all seemed fine (no corrosion, very clean). Did I need to pull the whole TPS unit off the pedal by undoing the two philips heads screws to check inside the housing? I'm really struggling to undo those screws without killing the heads of them - I've let them soak in wd40 for a while hopefully helps.

Last thing I found while digging around was a couple of of red wires cut off in the engine bay which come back to a plug inside under the dash (seems to have been painted black for some reason) not connected to anything, pictures attached also. Any idea what that could be?

Cheers,

-Scott

 

[charlie strayarc]

I would try completely disconnecting the cruise control and see if that makes a differance.

 

[scottm]

Neutral position switch

Hi All,

Latest update.

After removing and reseating the TPS and generally cleaning up some of the wiring under the dash I took it for a spin and the problem is as prevalent as ever (which is kind of good because troubleshooting something that is not as intermittent as it was will make life easier).

Anyway, after a drive around the block and the car performing the same way (no acceleration as soon as I leave my drive way, it seems especially when I put my foot down quickly) I drove home to unplug the NPS (neutral positioning switch) but it seemed that it had already been unplugged (please see attached photo). Can anybody confirm that is indeed the NPS? If it is then it is certinly not the problem as it's clearly already been unplugged.

I also noticed another wire under there (labelled in photo as being broken off) which I have no idea what it is but could be a problem? It might have something to do with an unrelated problem of the transmission intermittently reaching very high heat for no apparent reason (no towing, no hard conditions etc). Can anybody tell me what it is? Should I try and solder the broken cable back on?

I guess it could still be the TPS (but inside the case rather than the connectors), or the aftermarket cruise control?

Any help much appreciated... Feel like making progress but not really sure where to go from here....

Cheers,

-Scott

 

[scottm]

Easiest way to test it if your unsure is unplug it and go for a drive, it wont harm anything, costs nothing and only takes a few minutes.

Have you pumped fuel primer? Does it go hard after 3 pumps or is it still moveable after say 7 or 8? If so air in the fuel line is culprit. Could be filter housing letting in air, split lines, o ring on filter not sealing. you can fit clear hose before and after filter (this is temporary for the test) and prime up filter then run car and check for air bubbles in the clear hose. Bubbles after filter but none before means filter housing etc is to blame. Bubbles before filter indicate hose leak pre filter.

But rule out the nuetral position switch first, it may not be the problem but costs nothing and these switches do strange things to these vehicles.

Hi Charlie,

Have tried the fuel primer and it went hard after exactly 3 presses (so hard I couldn't press it anymore).

Does that rule that out completely?

Cheers,

Scott

 

[scottm]

I would try completely disconnecting the cruise control and see if that makes a differance.

Hi Charlie,

Problem is that it looks pretty tricky to unplug, it all looks like it's in line to the rest of the wiring and disconnecting it looks like it would stop stuff from working. But I'll have a further look.

Cheers,

-Scott

 

[scottm]

Further update. I just unplugged the Cruise Control system (just the two boxes) and took it for a drive and it still cut out.

Also soldered the broken cable from the previous image and it still cut out.

Vehicle seems to be doing it pretty consistently now (more regularly, more severely) I get out of the drive way and go to accelerate and get nothing, if it starts going if I accelerate quickly it almost always cuts out straight away.

I think I've ruled out:

Neutral Position Switch
Broken Cable from other sensor on transmission as photographed in previous post
Air in fuel line (as primer goes hard after 3 pumps)
Two plugs on the TPS not corroded.

From suggestions already submitted it could still be the actual TPS unit itself.

At a bit of a loss. Look forward to hearing suggestions.

Thanks again!

-Scott