After driving my vehicle on a few separate occasions now I still have an odd idle when the motor is cold. Outside temperature does not seem to play a role in this issue, only the actual motor temperature.

For example, I get in, start the engine, put the vehicle in drive or reverse (doesn't matter), and while holding the brake, I can feel a flutter/fluctuation in the steering wheel. I've been watching my idle and if the needle moves, its so slight that I can't verify that it does. However, what I do know is that something just still does not seem right.

Tonight to run a small experiment I moved my Expy off the street and into my driveway. Engine cold, I started it up and pulled up in front of my driveway, placed the truck in reverse to back in, and only using the idle speed of the engine, allowed it to slowly back up. The whole time its like the idle likes to dip slightly low at one point, give me the flux I feel in the wheel, and then the engine rpm's kick up to overcome it. I even parked it for a moment and I got out and listened to the engine. I could hear the engine idle speed go up and down - but it's not much. I stared at my tachometer and I haven't seen the idle budge. Tach reads normal as it always has from what I see - about 600 rpms.

However, when the engine is at operating temperature and warm. The idle issue is not present. The engine just hums away like a sewing machine - quiet and smooth as it should be.

My guess at this point is that the IAC needs to be cleaned and maybe the hose that leads from the PCV valve on the valve cover needs to be replaced? I remember inspecting the rubber 90* bend at the IAC and a while back and I wonder that by inspecting it by moving it around and checking the rubber's flexibility, if I didn't somehow collapse the tube internally which is causing me this problem.


And while I'm at it...

Another thing I've noticed, and I have no idea if this is normal or related but I have noticed while in fourth gear (OD) cruising down the highway at 55 - 65 mph, if I give the engine a little gas (say an 1/8th to 1/4th pedal movement down), the rpms will kick up 300 - 500 for a second and then drop back down to where it was previously before applying and throttle. In other words, if I was traveling 55 mph at 2000 rpms, gave it a little gas (but not enough to downshift), the rpms would kick up to 2300 to 2500 rpms for a second, and then immediately fall right back down to 2000 rpms.

Any thoughts on this? Normal? Related to cold idle in any way?

 

Did I stump the boards?

 

i had the same problem a couple days ago it just happend once, sinc then i havent had this issue again. sorry not a lot of help.

 

No, it more likely that people didn't read your post. It's fairly well known that most posts over two paragraphs go unread.