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Discussion Starter #1
I did a search and didn't find anyone with the same problem as me.

My 2.4 Hb auto has a wierd idle problem, when I start the truck the idle kinda wavers between 900 and 1100 rpm's but as it warms it goes from 800 to 1500 back to 800 back to 1500 and that quick.

I have changed the entire TB and thermostat just because and this changed nothing still has the wierd idle with a second TB.

I was wondering if the ECU might cause this or ??? I have never had a truck do this before and now I'm lost on what to tackle next. :eek:
 

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Discussion Starter #4
OK I just checked the repair manual that I have and I changed that with the TB and I can't see where they would both do the exact same thing.
 

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Do you hear anything clicking while the idle is running up and down? I'd make sure that you don't have an EGR problem causing the engine to starve, only to have the ECM overcompensate. I'm not sure if your truck has one or not, but I'd check and see if you have an idle compensation solenoid by the throttle cable. I had a non nissan vehicle with one that got out of adjustment, making the exact same symptoms that you are describing.

I would also recommend that you check ALL vacuum lines. I was having idle problems of my own, and finally found the hidden culprit, which was a vacuum line going to my TB. In total I found and replaced about a half dozen rotten lines. My truck would run like new when in open loop mode (cold), and would then run like crap once warmed up. I've finally exorcised that gremlin. I don't know about where you're at, but it seems like numerous co-workers have been afflicted with rotten vacuum lines around where I work recently.
 

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Discussion Starter #6
Still doing the same and there is nothing left to replace...

It has a new

EGR
Complete Throttle Body and everything thats attached to it.
Plugs Wires Cap
Vacuum lines

it was even at the dealer... Nothing, no idea's..

I give up...
 

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Mass air flow sensor?
 

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There's a cam on the fast idle lever and 2 lines that the cam should set between... with the cam between these 2 lines it should about .040" clearance. If the cam is closer than that the cam will not clear the hump of the lever.
 

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Discussion Starter #14
Thanks for all the replies and I'm happy to say that I fixed it and it runs like a new truck.

I changed the Air Charge Temperature Sensor, fast idle warm up cam for the fourth time and that thing that hangs of the back passenger side of the aircleaner and any vacuum lines that were a little suspect. (gotta love Pick N Pull) and now it's perfect. I just can't believe that three fast idle cams were no good, they were used but to have four of them shot... just wierd...

This is the little truck I have been working on, I can't believe the shape it's in for a 88.

 

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Man you're lucky,... these trucks never make it to the junk yard here in Texas! They get towed to south of the border where they're sold for $5000 easily, after you sold it for a measely $1500-$2000 bucks!
 

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Discussion Starter #17
Man you're lucky,... these trucks never make it to the junk yard here in Texas! They get towed to south of the border where they're sold for $5000 easily, after you sold it for a measely $1500-$2000 bucks!

WOW I wish I lived way down there, I live in BC Canada and I did just sell it for $2,100.00 to some lady that came by and just had to have it. Now I'm looking for another but with a five speed, the auto is nice but a little under powered.

Heres a pic of the last one I had before my Blue 1988 pickup, it's an 88 as well. I like these little trucks.







This is what the Red one looked like just after we bought it. We had just bought the 16inch rims and tires that day and it went to the body shop two days later.

 
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