4.9 Iac problems
Thread Starter
|
Senior User
Joined: Feb 2006
Posts: 132
Likes: 0
4.9 Iac problems
1988 4.9/5spd. Almost sure the iac is bad or what ever sensor tells it what to do is bad. Starts well but no high idle for any prolonged period. idles well cold(just a little miss). When I put any load on it the motor will bog. when it warms up it will accelerate pretty well but it will still miss if I really step on it. So after it has been running well and fully warm if I shut it down and restart it it will start bogging under load again. So far I have good plugs,cap,rotor,fuel filter, air filter, cleaned iac, checked timing with spout unplugged. I am leaning toward replacing the iac or the coil or both. the nipple on the coil had some corrosion on it when I changed the wires. I sprayed it down with electrical cleaner. smells a little rich. thanks in advance for any help,Joe
Der Postmeister
Joined: Sep 2006
Posts: 6,859
Likes: 560
From: Long Beach, Calimexiforia
Remove & clean. Reinstall the IAC. At warm idle, disconnect it. Idle should stall or close to it if it's good. http://www.fordfuelinjection.com/?p=39
Error code scans would help you, except in regards to the IAC (IAB), as it is actually a solenoid valve.
Error code scans would help you, except in regards to the IAC (IAB), as it is actually a solenoid valve.
Thread Starter
|
Senior User
Joined: Feb 2006
Posts: 132
Likes: 0
No cel and no codes yet. New info. When the engine is warm and running well, then turn it off. start back up and work the throttle to around 1500 rpms for a few seconds. runs fine again. Please help me fix this or i'll regret selling my '72 f100 even more.
Der Postmeister
Joined: Sep 2006
Posts: 6,859
Likes: 560
From: Long Beach, Calimexiforia
Remove & clean. Reinstall the IAC. At warm idle, disconnect it. Idle should stall or close to it if it's good. Ford Fuel Injection Idle Air Bypass (IAB)
Error code scans would help you, except in regards to the IAC (IAB), as it is actually a solenoid valve.
Error code scans would help you, except in regards to the IAC (IAB), as it is actually a solenoid valve.
Der Postmeister
Joined: Sep 2006
Posts: 6,859
Likes: 560
From: Long Beach, Calimexiforia
Low idle, EVP sensor pooched & clutch needed to be depressed during test.
Did you clean the IAC?
Did you clean the IAC?
Trending Topics
Thread Starter
|
Senior User
Joined: Feb 2006
Posts: 132
Likes: 0
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
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
Der Postmeister
Joined: Sep 2006
Posts: 6,859
Likes: 560
From: Long Beach, Calimexiforia
I'll go w/ pooched EVP sensor & IAC. Unplugging it should crash the idle. Sounds like the ECU is attempting to work around it (enable an idle w/o proper IAC function).
Der Postmeister
Joined: Sep 2006
Posts: 6,859
Likes: 560
From: Long Beach, Calimexiforia
Well it's not a sensor, so you shouldn't have to, but it won't hurt anything to do so either.
Where those codes w/engine off, continuous memory, or while running?
Where those codes w/engine off, continuous memory, or while running?
Thread Starter
|
Senior User
Joined: Feb 2006
Posts: 132
Likes: 0
codes were koeo. I don't know what the odds are but after 3 cycles with key it was really running bad. Now I have no power to the fuel pump. checked the relay and a wire has corroded itself loose from the connector. So i'll be needing some help with that too. Can't get the connector out of the housing. When it rains it pours.
Der Postmeister
Joined: Sep 2006
Posts: 6,859
Likes: 560
From: Long Beach, Calimexiforia
codes were koeo. I don't know what the odds are but after 3 cycles with key it was really running bad. Now I have no power to the fuel pump. checked the relay and a wire has corroded itself loose from the connector. So i'll be needing some help with that too. Can't get the connector out of the housing. When it rains it pours.
Der Postmeister
Joined: Sep 2006
Posts: 6,859
Likes: 560
From: Long Beach, Calimexiforia
I think it has a spring loaded leg that catches on a lip in the connector housing. You may be able to compress the leg from the other side w/ a pin or jewelers screwdriver. Magnifying glass would help!