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Discussion Starter #1
Hey Guys,

I've searched and searched and searched. Then searched some more. Then did some googling. And Binging.

Then I gave up. I've been lurking here for a while, but haven't found anything that's helped yet.

So, the problem:

I've got an 06 Off-Road that I bought last November. It's a 6MT. Unlucky me, but while I DID know about the SMOD problem (manual, no problem there), I didn't know about the stupid timing chain issue until a month after I bought it and started wondering about the whining noise. $1200 dollars later, problem solved. Ran great for a couple months, then started having a slight hesitation issue.

And I mean slight...when cruising down the road generally at a low rpm (between 1000-1500) I feel a slight misfire going on. Nothing drastic...no nose dive or anything, just like it loses some power for a few seconds, then kicks itself back to running smooth. Seems to be worse when it's cold (sometimes it'll dive like I let the clutch out too fast when it's cold), but generally you only feel it under light throttle conditions at a low rpm. I've cleaned the throttle body, MAFS, replaced the spark plugs, and run a bottle of lucas through the fuel and seafoam through the engine, nothing seems to make it better. No lights, no codes, nothing.

Possibly related: it seems to idle rough-ish. Not like misfiring, just not a smooth, imperceptible idle. Unfortunately, I don't know if that's just the engine or the fact that something is broken (my old VQ35 pathfinder idled way smoother than the X, but it's a different type of vehicle too).

6MT question:

This clutch seems to take a fair bit of force to shove in, and doesn't engage until the last couple inches of travel. Is that normal? Or should I expect a clutch job in my near future?

Thanks in advance!
 

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My clutch engages just about 3-4 itches for the top of the throw and has since day one so I think that is pretty normal. I believe there is a thread here somewhere about that being adjustable. Rough idles in these are common from what I've read and felt. The misfire feeling thing is something I can't relate to but I'll probably feel it on the way home today now that you've mentioned it haha.
 

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That sounds about normal for the stock clutch.

Here is how to adjust it....

Rough idle is pretty common. Could be motor mounts but my 2011 idled rough since the day I bought. I have a bully dog tuner with the idle running high and it is smoothed out. Some people have luck with the idle relearn.

As far as the missing goes.... Code? I would start with checking air filter and clean the MAF. Edit: I reread the fist post so ignore that last part...
 

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Discussion Starter #6 (Edited)
Hey, thanks for the responses. I'll have to see about adjusting the clutch...I knew it was possible but didn't want to mess with it until I knew if an adjustment was likely to make any difference. Now I know; thanks for the link!

As for the real issue, I'm not totally sure it IS misfiring, but that's what it feels like. I definitely triggered the misfire code when I did the seafoam thing, but that was a way worse shaking/hesitation than this is. It's really been driving me nuts, but I'm not even sure where to start diagnosing. Do we have a cam/crank sensor that could intermittently miss a little (those things are pretty solid state, but who knows?)? I've considered all this stuff:

Dying coil pack/weak spark (has new plugs but the coils are original)
  • Any ideas how to check that?
Bad gas (put water remover stuff in there, and a few tanks with lucas as well)

  • had a car that used to hesitate after each fill up. Finally drained all the fuel out one day and it ran great ever after. Maybe try the same with this?
Carbon build-up (seafoam smoked like hell, and I have no clue if the stuff actually works or not, but w/e, worth a shot)

Throttlebody/Accelerator pedal sensor
  • do these ever go bad/is there a way to test it?
Overactive Knock sensor dumping timing
  • Any way to test this? I don't have anything that updates fast enough to give me a good idea if it's dumping timing or not
I have (in the past) used a Consult to bump up the idle and that does smooth it out wonderfully, but didn't do a thing for the hesitation issue. I hate to be a pioneer with this problem, but it's driving me nuts. It probably wouldn't even be noticeable if it was an automatic!

Thanks for the input

CRMW07 > Sorry about that! Hope you didn't feel anything on your way home! :D

satown210 > Random gears, random rpms generally below 1500, but really light throttle inputs (scangauge usually says less than 10%). Always under smooth cruise situations (like 50 mph cruising down back highways on my way to work). Definitely not lugging it, but as soon as I stomp the gas, the hesitation disappears and it pulls like normal. It's never missed when I stomp the gas (fortunately...there's nothing worse than wondering if your car is gonna go when you floor it out into traffic!).
 

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I had the random feel of a misfire with mine a bunch of times. The computer in the truck learns your driving style, and I use cruise a lot. I was having the issue when I wasn't using the cruise, turns out the computer was still learning my driving style. Yours might have been a similar situation. Took a month or so for it to go away. This was when I had less than 50k on the truck also.
 

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Discussion Starter #8
I had the random feel of a misfire with mine a bunch of times. The computer in the truck learns your driving style, and I use cruise a lot. I was having the issue when I wasn't using the cruise, turns out the computer was still learning my driving style. Yours might have been a similar situation. Took a month or so for it to go away. This was when I had less than 50k on the truck also.
Yeah, it's been this way for a loooong time, and I can definitively say it wasn't the computer (original had the issue, then I fried it (oops), got a new one from the dealer, and the issue is still there). I use cruise control a fair bit, but I think I can still feel it hesitating with the cruise on, which should rule out the pedal sensor, but not necessarily the throttle body. It's an aggravating problem :dontknow:
 

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Issues like these suck, it really can be anything. I've bought and sold a lot of cars that had hesitation / missing problems without codes.

Here are a few things that I've come across that caused them.

1. Bad distributor - missed at preceise RPM only (doesn't apply to us though)
2. Dirty throttle body
3. Vacuum leak
4. Worn crank gear allowing timing to shift (only heard of this on Toyota 3.4)
5. Bad MAF
6. Bad spot in TPS


If everything was fine before timing chains and now it is doing that, I wonder if the timing is off just a tooth.
 

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If the timing was off a tooth you would feel it all through the rpm range and throttle range.
 

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Not specifically a Nissan 4.0 but I had a montero that was off one tooth and it hesitated on low rpm not all the time but was fine once it got past 2000 rpm
 

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False.

There can be a misfire that is not severe or occuring enough to throw a code.

What gear are you in when it is missing? 1000-1500 RPMs, you might be lugging it.
By which you mean occasional and insignificant? Because if it fails to light three times in a row, it'll throw a code.
 

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Again just because there is not a misfire code does not mean there is no misfire happening. The OP even said the "misfire" feeling does not happen all the time. So he may have something causing a brief misfire.

You are saying 3 misfires in a row cause a code? Most cars require more than that to throw a code. 3 misfires in a row would happen in about 2 seconds.
 

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Even less. At 3,000 rpm, each cylinder fires 1,500 times a minute.

But maybe it is only a pending fault code not a fault code. I can't remember.

Let me say it more precisely. If there is no misfire code, there is not an ignition fault that needs repair. This is the most very basic aspect of OBD.
 

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Water in fuel or dirty filter.
Weak or failing fuel pump.
Replace diff oil to make sure you dont have a tooth or something floating around
Check that there are no brake calipers grabbing
And, even though you cleaned the throttle body I'd check that again. These are drive by wire and the throttle can be doing anything different from your right foot or have a stiff spot, my 06 got replaced under warrantee for having a mind of its own.
 

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Even less. At 3,000 rpm, each cylinder fires 1,500 times a minute.

But maybe it is only a pending fault code not a fault code. I can't remember.

Let me say it more precisely. If there is no misfire code, there is not an ignition fault that needs repair. This is the most very basic aspect of OBD.
Sorry gotta disagree again. If it was a coil that was cutting out briefly but then fine again no code and that is an example of an ignition component that needs repair. Just because there is not a code does not mean the ignition system is fine.

My Infiniti will sit there and mis-fire forever before it throws a code. My model is known for bad coils. I have to wait for the misfire to get worse before it throws the code so I know what cylinder it is.
 

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Discussion Starter #17 (Edited)
Water in fuel or dirty filter.
Weak or failing fuel pump.
Replace diff oil to make sure you dont have a tooth or something floating around
Check that there are no brake calipers grabbing
And, even though you cleaned the throttle body I'd check that again. These are drive by wire and the throttle can be doing anything different from your right foot or have a stiff spot, my 06 got replaced under warrantee for having a mind of its own.
Water in fuel or dirty filter is sure what it feels like...not a total loss of power, but just a few seconds of stuttering/hesitation that clears up on its own, or can be fixed by pushing the pedal a little farther. I hate drive by wire =( and I don't have a tool that will show me pedal position vs throttle position in real time. All I can get is TPS, which I assume is talking about the throttle body, rather than the accelerator pedal. Honestly doesn't feel like the throttle is closing (the loss of power is accompanied by a slight shuddering), but I haven't ruled that out either.

How about oxygen sensors? Long chain of events, but if one of the sensors is losing it's mind, it might throw the mix lean and cause a bit of detonation, knock sensor gets mad and dumps timing, hesitation. But I've never seen an O2 sensor need to be replaced without throwing a code.

Do we have a drain on our fuel tank, or do I need to pop the return line off the fuel rail and let it run itself dry? (if I want to empty the tank)

Also pretty positive it ran fine for at least a month after the timing chain issue was fixed. And I'm afraid OBD is just like every other computer program in the world. If your problem doesn't meet the exact specs it was programmed to throw a code for, it will just keep on assuming everything is fine. Computers are the smartest dumb things on the planet.

I know nissan has had ****ty MAFS in the past (had to replace a mafs on my pathfinder for a similar issue, but on that is was only under heavy acceleration that it hesitated), but has anyone heard of mafs issues with the VQ40? I might try that if it's not prohibitively expensive.
 

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No drain on the tank. I doubt that's it. If there was water in the fuel it would miss all the time.
 

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Discussion Starter #19
I have seen missing due to a fuel issue in the past, but that only happened right after refilling at the gas station (I assume the fresh fuel was kicking up the garbage in the bottom of the tank). This has no real rhyme or pattern behind it, except that it's more pronounced when the engine is cold, and it's at light throttle, low rpms. So aggravating.
 

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Ps. Drive by wire has some real benefits. It allows for a complete remap of throttle response while in low range. Very cool especially for us MT fans. And there's no separate idle air control valve that needs maintenance and adds complexity.
 
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