Before I installed a new IAC sensor/ motor, maybe twice or thrice a week, my idle would get hung up at around 1k-1100 rpms, when I would decelerate, and come to a stop. Usually, a quick tap of the long pedal would get it to drop back to it's normal 590-600 rpms. So I took the throttle body off, cleaned it up, and slapped a new sensor in.

It worked perfect for about 2 days. Now, every morning, and every day after work (after sitting an extended period), it seems to start kind of rough, and the idle will jump up to 15-1600, and stay there until I blip the throttle. (In the driveway). Then as I'm leaving the neighborhood, at stop signs, red lights, and the such, the idle still sticks around 1100 rpms, and as I push the clutch in to shift gears, the throttle jumps to the 2k range, and I have to blip the throttle 2-3 times before it'll drop down to regular levels. The bad part, is sometimes, as I'm coming to a stop, say in 2nd or 3rd gear, I can feel the truck trying to pull, since the idle is stuck, and I have to brake harder, and try to blip the throttle, with the clutch engaged, before I stop. It's crazy.

I'm just wondering if y'all think it may be a faulty IAC sensor, or something else. It worked fine the first 2 days. The idle didn't hang up once for those 2 days. One other thing, that may or may not change the situation. The same time I did the IAC sensor, I also installed a new battery terminal thingy, to clean up my offroad light wires, so I didn't have the 6 rings hanging off of the regular terminal. My guage in the cab reads fine voltage, but would a slightly lower voltage or anything make the truck act like that?? Like maybe it's trying to idle higher to stay running? I'm lost at this point. I kind of ruled that idea out, since when I blip the throttle and it drops to 600 rpms, it'll idle there without any hesitating or sputtering or anything.

Any thoughts or ideas appreciated. Not only is it wasting my gas, but it seems kind of dangerous sometimes, when the idle hangs up, and it pulls, even though I'm braking, while I try to blip the throttle, before I come to a stop. Suppose I could go buy another IAC sensor, but this one was about 40$ dollars, that I'd really rather not buy again. If needed, guess that's what I'll do though.

 

Possibly a faulty IAC, also could be TPS..... If the PCM thinks you are still stepping on the long-pedal... it will feed gas accordingly.

 

I know the feeling, mine would surge mostly in line at the drive thru. It gets really annoying when your truck decides to rev on its own and the people in front of you think its you just being inpatient. I had to go through two replacement IAC's from o'reillys. See if they can replace it as faulty.
On a side note, how you like the treadwrights? been really debating getting them

 

Thanks u 2 for the input. TPS, was another sensor I'd considered, but dang...change one sensor, and all of a sudden have to change 'em all? Sounds like my kind of luck; I'm about to do a manifold swap with one i modified, and I'd like to get these issues figured out, before I start switching things up. And yeh krichards, the drive-thru thing is exactly what I'm talking about. And same with when I get off the interstate, if I pull up behind someone. The idle likes to stick then also, after a steady rate of 60-65 mph for 10-15 minutes, on the way to work. When I get off the exit, the idle is usually stuck. I can almost plan on it then. And the occasional sitting at a red-light, rev-up, without me even touching the throttle; the people in front of ya start scooting forward, thinking you're getting ready to run them over.

Side note: the treadwrights, from my experience, are well worth the money. 480$ to have a set shipped to me 3 years ago, and I have done nothing but rotate them, like any other tire. They are probably 40-50% tread remaining, and I'll be buying a set of 285's ( 33's, guard dogs, same tread pattern) end of this year, or beginning of next. They tear thru snow and mud, and haven't left me stranded yet. Including some major snowfall, where the entire city pretty much closed down, I was out rollin' thru it. Only downfall I've noticed is braking in the rain, they can get squirrely, but a light foot can take care of that. As I can imagine many offroad tires may do, given the lower % of rubber to pavement contact. I have 0 issues with them, and 2 outta my 4 tires have plugs from nails in 'em, or i'd definitely run 'em til next tax season or farther. But plugged tires doing 65 mph on the interstate makes me nervous. and I have to do it every morning.

 

good luck with that surging, it gets kinda hairy. Thanks for the info on the treadwrights. I plan on purchasing a set of the 285's also, trying to decide if i can bring myself to step down from 315's

 

@ bekins01ram. Was the battery disconnected when you cleaned the TB and put the new IAC in? What brand IAC did you install? And if you get a Haynes, and an inexpensive multi meter, you can test the TPS, and all the other sensors for that matter. You can test the charging system also.

 

I did disconnect the battery before removing the throttle body, and the IAC was "Master Pro Ignition" brand from o'reillys. 32.99 before tax. A multi meter is something that really oughta be in everyones garage, but I dont have one...yet. Will the haynes manual have a listing of what the voltages should be for various sensors? The IAC was what the oreillys guy called their "house" brand, and they also had another more expensive one, but I dont remember what brand it was. Maybe if they'll let me exchange it, I'll upgrade to the pricier one, and pay the difference, while I invest in a multimeter as well. :P I do remember him mentioning both had warranties, I just don't know if the warranty covers it once installed. Thanks for the advices.

 

of course the warranty applies after install...... why wouldnt it? thats why they have warranties...... so something can be covered after install if the product fails prematurely.

 

It will be hard to measure voltage. Easier to measure resistance with no voltage applied.

 

idle problems are usually either IAC or TPS. my experience has been that surging idle is TPS. inability to idle is IAC.

i keep any known good sensors as spares, in order to toss in a new one without any cost