Posted: Mar 06 2008 at 3:15pm | IP Logged

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adam85;

Posted: Mar 07 2008 at 1:23pm | IP Logged

another thing to keep in mind, and I have noticed will all the nissans i have driven..when a cold start is executed. the chokes on these computer controlled motors will have the rpms run up to about 2000-2500k and then drop back down, sometimes lower, part of it is due to oil pressure as well i would guess until it stabilizes you will also notice that as your engine gets warm, the idling rpm will drop to under 1000k, on my SE 3.3, it'll be around 600. if you had an auto tranny, you'd also notice that until the tranny gets warm, the torque converter won't lock up, and until that happens i run around 2000 rpms around 45 mph, after it does..the rpms drop by a few hundred. all this says is that until this happens, in theory i'll be using more gas until my engine/tranny is warm, because the choke/torque converter need time to let things to get to operating them.

the rpm gauge, could be out of cal, are you having rough idling?

Posted: Mar 07 2008 at 5:53pm | IP Logged

adam85,

You mentioned a bucking problem while cruising in 3rd gear.  Does it buck in other gears or at other times?  If you put it in 4th at say...30 and floor it, does the bucking get worse? How about going up a hill in high gear at low RPM?  There are 2 common problems that will create a "bucking" feeling. 1) a bad plug wire  2) dirty fuel injector connector.  Nissans are notorious for the injector connectors to build up corrosion in them.  With the mileage you've got on your truck, I would check them both.

Posted: Mar 13 2008 at 6:38pm | IP Logged

adam85,

I didn't mean a dirty injector itself, what I meant was the electrical connector that plugs onto the injector has a tendency to build up a greenish color corrosion in it which creates a high resistance which in turn prevents the injector from firing(injecting fuel).  This type of missfire is unpredictable, there is no rhyme or reason to it as far as when it happens, where as a bad plug wire will rear its uggly head when the engine is under a load (going up hill in high gear is most obvious).

As for your high idle, a common problem among lots of cars is a dirty IAC valve or Idle Air Control valve.  What it does is lets in (meters) a small amount of air past the throttle body.  Well, it has a tendency to build up dirt and carbon inside the valve which can reduce the opening size and also hold it open.  If you feel capable (tools and manual), you can clean the IAC with a spray fuel injector cleaner designed for the throttle body.  If you don't feel comfortable doing it yourself, then don't!!  As an ex-mechanic, the one thing I hated the most was when someone tried doing something themselves and screwed it up. Then had the car towed in to me.

Keep us informed and take care!