IAC issues
Thread Starter
|
New User
Joined: Aug 2015
Posts: 6
Likes: 0
IAC issues
Hey Guys,
First post here and hoping you can help.
1992 F250 351w injected not carb. Idle was hanging and high when changing gears (around 2500rpm)... Replaced TPS, still high idle. Replaced IAC, still high idle. Unplug IAC, idles ok. I replaced with a Borg Warner IAC.
Scanned for codes... nothing related to TPS, IAC or throttle body. Do you think the replacement IAC is just stuck open?
thanks in advance.
Dennis.
First post here and hoping you can help.
1992 F250 351w injected not carb. Idle was hanging and high when changing gears (around 2500rpm)... Replaced TPS, still high idle. Replaced IAC, still high idle. Unplug IAC, idles ok. I replaced with a Borg Warner IAC.
Scanned for codes... nothing related to TPS, IAC or throttle body. Do you think the replacement IAC is just stuck open?
thanks in advance.
Dennis.
Senior User
Joined: Jan 2015
Posts: 123
Likes: 0
That's always a possibility. I don't think there is a code for the IAC. At least not on my 87. I had a Bronco II that had idle problems. When I replaced the IAC it didn't help the situation. Hopefully that's the case for you as the IAC is easy to get to. Good luck.
Fleet Owner
Joined: Oct 2005
Posts: 20,783
Likes: 1,748
From: Kentucky
Please define "ok"
Senior User
Joined: Nov 2012
Posts: 381
Likes: 0
i had this problem on my 92 f150 5.0l
would idle some what fine unplugged. plugged it up it would be around 2000,2500rpm.
so i left it plugged in and drove around for a few blocks brought it back to the house and unhooked the battery for about 30mins or so,then it was find. cold start it will idle on high idle for about 20-30 sec then come down, or you can kick it off bye just hitting the gas real quick. its been fine ever snice.
would idle some what fine unplugged. plugged it up it would be around 2000,2500rpm.
so i left it plugged in and drove around for a few blocks brought it back to the house and unhooked the battery for about 30mins or so,then it was find. cold start it will idle on high idle for about 20-30 sec then come down, or you can kick it off bye just hitting the gas real quick. its been fine ever snice.
Thread Starter
|
New User
Joined: Aug 2015
Posts: 6
Likes: 0
No fast codes, Continuous memory codes as follows.
172 ego not switching, lean exhaust - bank 1, ego not switching, rich exhaust - bank 1. 334 EGR (evp) voltage above closed limit.
idles ok means idles at a consistent and smooth 750rpm.
I have also smoke tested the vacuum system - no leaks detected.
172 ego not switching, lean exhaust - bank 1, ego not switching, rich exhaust - bank 1. 334 EGR (evp) voltage above closed limit.
idles ok means idles at a consistent and smooth 750rpm.
I have also smoke tested the vacuum system - no leaks detected.
New User
Joined: Aug 2015
Posts: 6
Likes: 0
Easy check on your new IAC valve. Pull the valve and have someone turn the key to "on," NOT "run." The plunger should move in and out with turning the key on/off. If it doesn't move, replace the unit. Same prob. on mine; the plunger was frozen and 2 cans of carb cleaner couldn't free it. A new IAC valve cured mine. Best of luck!
Trending Topics
Fleet Owner
Joined: Oct 2005
Posts: 20,783
Likes: 1,748
From: Kentucky
Idle RPM @750 w/IAC disconnected is WAY too high, Verify the throttle stop screw has not been jacked. If it looks factory then you have a vacuum leak. The throttlebody can have worn bushings and/or blades and still pass the smoke test.
Your lean code still makes me think you have a vacuum leak. Code 334 means the EGR may not be fully closing. Another source of unmetered air.
Your lean code still makes me think you have a vacuum leak. Code 334 means the EGR may not be fully closing. Another source of unmetered air.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Ford Super Duty: 5 Things Owners LOVE, 5 Things They LOATHE!
Joe Kucinski
Every 2026 Ford Truck Engine RANKED from WORST to FIRST!
Michael S. Palmer
The Best F-150 Deal of Every Trim Level (XL through Raptor)
Joe Kucinski
Thread
Thread Starter
Forum
Replies
Last Post