Truck Idle Issues

[bduke23]

Posting this here instead of in the 3.0L forums because I am not sure if this is specifically a 3.0L problem.

My truck started acting up the other day. When shifting gears, the idle would sometimes randomly skyrocket to 3500 rpm. I figured no brainer, its the IAC. I had one that I had ordered previously, so I swapped it out, plugged the new one in, thinking that would be the end of the problem.

As you may have guessed, that didn't fix it. Here is what its now doing:

When first started, the truck high idles like normal till its warm, then drops to 750. The first few shifts of city driving, it acts completely normal. Then all of a sudden in between shifts it will rev to 3500 again. Then, sometimes it will be normal. When it revs high, if I lug the engine in gear to almost stalling then push the clutch in, it will idle to 1500 for a couple seconds, then drop to 1100. I can also feel it when I am driving. If I take my foot off the gas, on occasion after a brief pause I can feel the truck pulling, like I stepped on the gas, except that my foot is still on the floor. Then, again randomly, it will quit. And, also seemingly randomly, on the same trip, through the same gears, and same speeds, it will quit doing its high rev thing and act completely normal. I am absolutely stumped. I figure the new IAC must be working, because it will correct the idle rpm whenever it feels like it.

I don't have a lot of time to look at it right now, because I go to school full time, then work a full shift after school, then go home and do homework all night (I am in mech. eng.). On top of that, I am moving to a new place and need to be out of my old place by this friday, so I need to fit moving in there sometime too.

Really confused, any help would be great!

 

[robertc1024]

Is your throttle cable sticking? When it revs really high, hook your toe under the skinny pedal and pull up.

 

[Ryannn]

When it was cold here my truck in the morning would Idle at 3k... and now that its warmer no problems.. thats just my experience.

 

[bduke23]

Never though of the throttle cable sticking, I'll try that.

Also, something I forgot to mention is every once in a while the check engine light comes on for about ten seconds, then goes out again.

 

[bduke23]

Anyone?

Checked the throttle cable, it is not sticking. I noticed when I put the new IAC on, that there is a black plastic dial on the side of, that spins freely. I have no idea what this does, if it even does anything. Something to do with this maybe?

Is there a way to pull the codes from an OBD 1 system? That way maybe I can see what is turning on my CEL for ten seconds at a time randomly.

 

[bduke23]

BUMP

I wonder if it could also be the computer? I had a similar problem on a Fiero, where it turned out to the computer. Only that car would always idle really high, whereas the ranger will sometimes correct itself, sometimes not.

 

[LearjetMinako]

Black dial on the IAC? Did you get the IAC from AutoZone? If so, return it and get one made by BWD. That AutoZone IAC is crap. Used one before to fix a Ford Tempo. Didn't work because it was not designed right to begin with.

 

[bduke23]

I got it from RockAuto. I cannot remember the brand off the top of my head. Came in a white box, with blue stripes, maybe some red in there. The IAC I took off the truck had the same dial tho

 

[Earl43P]

http://www.therangerstation.com/Magazine/Summer2003/VacuumLeaks.htm

http://www.therangerstation.com/tech_library/OBD_I.html << Pull codes

Might try ruling out EGR by disconnecting the valve.

 

[bduke23]

Ok I pulled the codes today. I got a code 167 and 122, which both relate to the TPS. Cleared the codes, and gonna pick up a new one tomorrow and put it in, and hopefully that'll fix the poblem.

 

[bduke23]

Got er fixed!

Pulled the codes, which indicated throttle position sensor. Went to the parts store first thing in the morning and got the last one in town . Got home...and the fun began

It was held in with two phillips screws...both loctited. And neither one could be reached, because the upper rad hose was directly in the way. I managed to force a stubby screwdriver in for the top one, and promptly stripped it. So the next hour or so was spent removing the upper intake from my engine, so I could slide it forward enough to get at the screws with my drill, and luckily a stripped screw extractor was able to remove them both. I went down to the hardware store, and got two matching screws WITH A BOLT HEAD to replace them. Put it on, buttoned everything back up, and she works flawlessly!

So to whoever used philips screws with loctite...