What's wrong with my IAC?
Thread Starter
|
Fleet Mechanic
Joined: Nov 2022
Posts: 1,697
Likes: 416
What's wrong with my IAC?
My truck has a new Motorcraft IACV I put in a while ago, sometimes it'll idle absolutely perfectly at 650, but it seems to struggle to do that, and the truck will be kinda stumbly at idle, and go high for no reason, even making shifting obnoxious, because the rpms don't reliably drop, a few things to note:
Unplugging it make the truck run amazing, great rpm drop when I release the pedal. Idle around 600
Plugging it in makes the rpms rise quickly, sometimes as high as 1700 or so. (Not exact)
Truck is pushing A LOT more air than it should with IACV plugged in.
Butterflys are shut 100% at idle, should I adjust the screw or no? (Very easy to adjust screw, doubt there is original loctite)
Idle is jumpy, sometimes misses, (doesn't miss when IACV unplugged)
Unplugging it make the truck run amazing, great rpm drop when I release the pedal. Idle around 600
Plugging it in makes the rpms rise quickly, sometimes as high as 1700 or so. (Not exact)
Truck is pushing A LOT more air than it should with IACV plugged in.
Butterflys are shut 100% at idle, should I adjust the screw or no? (Very easy to adjust screw, doubt there is original loctite)
Idle is jumpy, sometimes misses, (doesn't miss when IACV unplugged)
Thread Starter
|
Fleet Mechanic
Joined: Nov 2022
Posts: 1,697
Likes: 416
No CEL, my new TPS fixed the code the previous one was throwing, can you pull the KOER codes with the paperclip? Or will it damage something?
Hotshot
Joined: Jun 2015
Posts: 12,844
Likes: 2,437
You have to do certain things (hit the brake pedal, goose the throttle, turn the steering wheel) when prompted during the engine running test.
Thread Starter
|
Fleet Mechanic
Joined: Nov 2022
Posts: 1,697
Likes: 416
I'm stumped because all these problems are related to my IAC, which I know can function properly, because it has
Trending Topics
Lead Driver
Joined: Jan 2019
Posts: 5,077
Likes: 865
From: N.W. Alabama
Vacuum leak, gasket bad, or tore/wrinkled on install
Fuel Injection Technical Library » Throttle Position Sensor (TPS)
How to Clean and Test your IAC - Ford Bronco Forum
Fuel Injection Technical Library » Throttle Position Sensor (TPS)
How to Clean and Test your IAC - Ford Bronco Forum
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
Thread Starter
|
Fleet Mechanic
Joined: Nov 2022
Posts: 1,697
Likes: 416
Suppose the screw has been messed with in the past (mayby previous owner) how would I set it back to where it should be?
Cargo Master
Joined: Jan 2004
Posts: 3,118
Likes: 149
From: South Dakota
For what it's worth, that is my '94 F-150 did when I unplugged the IAC, idled about that RPM, before I figured out my TPS was bad causing it to idle MUCH faster and make my E4OD transmission shift through the forward gears with a great JERK. Yes I realize you replaced the TPS, so it may not be worth anything.
Thread Starter
|
Fleet Mechanic
Joined: Nov 2022
Posts: 1,697
Likes: 416
Update
I made the decision to perform an idle reset, using the screw (I have a feeling it was messed with in the past) HUGE difference, not perfect, the IAC still sometimes hangs around 2k when trying to shift into 2nd gear, but it now reliably drops to ~650 idle, and it is so much smoother, not stuttery or shaky.