# 88 Pickup Variable Idle when Cold, High Idle when Warm



## dbsoundman (Feb 3, 2013)

OK, so my 88 has a new IACV, new fuel injectors, MAF, spark plugs, hoses, AND the entire throttle body, as well as other items I don't remember at the moment. It runs fine, but it does exhibit some odd behavior when idling. When the engine is cold, the idle tends to vary, going low, then high, kind of back and forth like a boat riding waves, centered around maybe 900 or 1000 RPM. When the engine warms up, it steadily tends to idle around 1100 RPM. Also, when driving, once I put my foot in the clutch, it tends to stay around the RPMs it was at while it was engaged, so if I was cruising along at 1500 RPM and put the clutch in, it tends to stay around 1500, and slowly drift down to 1100 or so. I don't think the actual throttle cable is sticking, but I'm wondering if the throttle is a little slow or dirty or something. I'm inclined to say it's not dirty since it's new, but maybe something just needs a little lubrication? I also heard that there is a wax pellet involved in the idle control that can dry out over time, but I'm not sure if that's my problem here or not, or even where that pellet is located (whether or not it's in the throttle, etc.).

I feel some random "bumping" at idle as well, I'm wondering if that's part of some of my idle problems as well. It's not like a backfire, it just feels like the truck is physically hitting a little bump, but it's not moving at all, and it's random.

I'd appreciate any thoughts/ideas! I'd like to improve the condition of this truck even more so it's a great, smooth running machine!


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## wilburk (Dec 29, 2012)

First thing you should do is check timing. There is also an idle screw that you could try adjusting while the car is running. 

And definitely get a Haynes or Chiltons manual.


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## tomit (Jul 2, 2004)

My guess is an intake air leak. Careful aiming of a combustible spray may identify the leak - the engine will speed up even more.

Be careful and good luck.

Tom


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## SPEEDO (Jun 9, 2003)

I am leaning towards a bad thermo element (or wax kit) its on the upper throttle chamber, it push's the fast idle cam (choke cam) its tucked into a housing that has 2 hose's going to it... try Google with this pt# 16391-12G00
it should pop up a pic, look for #16394J


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## dbsoundman (Feb 3, 2013)

SPEEDO said:


> I am leaning towards a bad thermo element (or wax kit) its on the upper throttle chamber, it push's the fast idle cam (choke cam) its tucked into a housing that has 2 hose's going to it... try Google with this pt# 16391-12G00
> it should pop up a pic, look for #16394J


Thanks, that was my suspicion as well. Once I get my Haynes manual I'll be able to find that damn thing and get it replaced, I'm assuming I can pick this up at a local dealer? Or should I order it instead?


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## SPEEDO (Jun 9, 2003)

word of warning, these things come compressed (mounted in a metal keeper with a spring keeping it compressed) so get the old one out first and dont take too long getting the new one in...
did you pull up a pick and look for the # I posted?


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## dbsoundman (Feb 3, 2013)

I found this (with picture): Nissan Parts, NISMO and Nissan Accessories - Courtesyparts.com

But it says it's for a pathfinder...

Also found a website with no pics, but it lists the exact part I think: 16391-12G00 - Nissan THERMO ELE KIT

Am I on the right track?


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## SPEEDO (Jun 9, 2003)

thats it! just the brass part is used the spring keeps it compressed.. try that pt# in Google images and look for pt# 16394J


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## dbsoundman (Feb 3, 2013)

SPEEDO said:


> thats it! just the brass part is used the spring keeps it compressed.. try that pt# in Google images and look for pt# 16394J


Interesting, and that part has the wax pellet in it as well? I can see now why you said to do it quickly, that is a heck of a spring...


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## dbsoundman (Feb 3, 2013)

Found a helpful diagram on the same website as the picture:









Also, what's annoying is that the previous owner replaced all of this stuff (see picture, don't ask me to name it all!) https://www.dropbox.com/s/fny5lb5xc814y45/2013-02-04%2018.21.35.jpg

But he did NOT replace that stupid brass piece...:lame:


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## SPEEDO (Jun 9, 2003)

the 16021 = injectors
16240 = fuel pressure regulator
16078 = hot wire modulator or air flow meter


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## dbsoundman (Feb 3, 2013)

Well, I still haven't gotten a chance to even order the aforementioned part, but I can rule out the fuel filter as a possible culprit at least...just talked to the previous owner and he replaced it.

My Haynes manual should be here tomorrow hopefully, but I'm curious, how hard is it to get to this thermo housing?


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