Rough Idle Multiple codes
Thread Starter
|
Freshman User
Joined: Dec 2020
Posts: 38
Likes: 0
Rough Idle Multiple codes
We got the fuel pump issues straightened up on my sons 92 F150 351w. Now on to the next problem. The truck idles rough and low (500 rpm) when its cold. It eventually gets better when warm but still has a bit of a lope. It has all new plugs, wires, distributer cap. I don't think that the coil is very old either.
It has a newer IAC but I've been reading conflicting info on testing it. Its getting 12V and the OHMS seem to be in range but when you turn the key on, it doesn't seem to do anything and if you unplug it while the engine is running, nothing happens. When I unplug the one on my 02 Escape, it dies right away.
We got various codes out of it. The check engine light came on after it had been driven a while. KOEO codes were 332, 558, and 565. I believe they are EGR related.
The running test gave us 411,412, and 126. 126 is MAP sensor higher than expected. Can that be the issue with the cold idle and is there a reliable way to test it? I'm having a hard time figuring out where to start and which issues are related. Any help or advice would be greatly appreciated. Thanks
It has a newer IAC but I've been reading conflicting info on testing it. Its getting 12V and the OHMS seem to be in range but when you turn the key on, it doesn't seem to do anything and if you unplug it while the engine is running, nothing happens. When I unplug the one on my 02 Escape, it dies right away.
We got various codes out of it. The check engine light came on after it had been driven a while. KOEO codes were 332, 558, and 565. I believe they are EGR related.
The running test gave us 411,412, and 126. 126 is MAP sensor higher than expected. Can that be the issue with the cold idle and is there a reliable way to test it? I'm having a hard time figuring out where to start and which issues are related. Any help or advice would be greatly appreciated. Thanks
Lead Driver
Joined: Oct 2016
Posts: 6,185
Likes: 633
From: Houston/Sugar Land
332 (R,M) EGR did not open/respond during test or if memory code, did not open intermittantly - EVR or PFE
558 (O) EGR vacuum regulator solenoid/circuit failure - EVR or PFE or Solenoids
565 (O) Canister Purge 1 solenoid/circuit failure - Solenoids
332 is in memory or you put it in the KOEO instead of KOER. That is what the R and the M mean. Memory means that it happened, but is currently not involved
These are the KOEO codes. They must be addressed before going to KOER codes. Looks like your EVR is highly suspect.
If the EVP sensor fails it can send an incorrect signal to the computer, which will affect the flow of the EGR system. Improper EGR flow may cause engine performance issues, such as difficulty starting, rough idle, and even misfires, which may be most prominent at cold starts.
Sandy
558 (O) EGR vacuum regulator solenoid/circuit failure - EVR or PFE or Solenoids
565 (O) Canister Purge 1 solenoid/circuit failure - Solenoids
332 is in memory or you put it in the KOEO instead of KOER. That is what the R and the M mean. Memory means that it happened, but is currently not involved
These are the KOEO codes. They must be addressed before going to KOER codes. Looks like your EVR is highly suspect.
If the EVP sensor fails it can send an incorrect signal to the computer, which will affect the flow of the EGR system. Improper EGR flow may cause engine performance issues, such as difficulty starting, rough idle, and even misfires, which may be most prominent at cold starts.
Sandy
Thread Starter
|
Freshman User
Joined: Dec 2020
Posts: 38
Likes: 0
The 332, 558, and 565 came up in the KOEO. There are 3 separate codes in the running test. The check engine light had came on after the engine was warm the day before. We warmed the engine up before the run test and it hadn't came back on, but we warmed it up at idle. We hadn't driven it. So is there a way to test the vacuum regulator without just slapping a new one on? Its sounds like that may be at least part of the problem.
Lead Driver
Joined: Oct 2016
Posts: 6,185
Likes: 633
From: Houston/Sugar Land
Fleet Mechanic
Joined: Aug 2015
Posts: 1,835
Likes: 364
From: Candy Mountain
The EGR vacuum solenoid can go bad, but it is not a common issue.
But, it will not work if it does not have a steady supply of manifold vacuum, and vacuum leaks are extremely common. The IAC not changing the idle supports the idea you have unmetered air entering the intake.
If you still have the factory plastic vacuum lines it is highly recommended you replace them wholesale. Ditto for the PCV system. You can check vacuum circuits for leaks with a hand held vacuum pump.
No or poor vacuum signal to the MAP sensor will also cause it to read out of range.
So, I would suggest you take a good look at your vacuum lines before you start throwing expensive parts at it.
But, it will not work if it does not have a steady supply of manifold vacuum, and vacuum leaks are extremely common. The IAC not changing the idle supports the idea you have unmetered air entering the intake.
If you still have the factory plastic vacuum lines it is highly recommended you replace them wholesale. Ditto for the PCV system. You can check vacuum circuits for leaks with a hand held vacuum pump.
No or poor vacuum signal to the MAP sensor will also cause it to read out of range.
So, I would suggest you take a good look at your vacuum lines before you start throwing expensive parts at it.
Thread Starter
|
Freshman User
Joined: Dec 2020
Posts: 38
Likes: 0
Thanks for the info. We just got 8" of snow so it may be a few days before I mess with it! I don't even want to go outside.
Trending Topics
Thread Starter
|
Freshman User
Joined: Dec 2020
Posts: 38
Likes: 0
After doing some digging, I was able to contact a previous owner. He's the one that replaced the 4.9 with the 5.8. He says that the motor is from an 89. I see on Rock Auto that the part # for the IAC Valve is different for a 89 and a 92. The IAC on the truck has a stem (like a vacuum line would attach to). It looks like the ones pictured for a 92. I haven't been able to find much about these but do you think its safe to assume that it is the wrong one? It looks newer like the previous owner replaced it. I don't know how much difference there is in them. My 02 escapes IAC looks almost identical but has a different connector. What do you think?
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
Fleet Mechanic
Joined: Aug 2015
Posts: 1,835
Likes: 364
From: Candy Mountain
The IAC has a breather vent usually covered with a black plastic cap. If the cap was removed it might look like a vacuum port. Without a cap you are more likely to get crud and water in the mechanism.
Fleet Mechanic
Joined: Aug 2015
Posts: 1,835
Likes: 364
From: Candy Mountain
Actually, scratch that part about the Ford part being the same... I checked some different catalogs, and it looks like the part changed a couple of times... but the part number posted above would be correct for a 89. I suspect you could use a later version and it would function the same.
Fleet Owner
Joined: Oct 2005
Posts: 20,789
Likes: 1,753
From: Kentucky
I think the earlier IACs have a diode built into them. The later versions the diode is built into the PCM.
https://www.fullsizebronco.com/threa...arness.337346/
Some discussion on the model year change over, 1998 vs 1989. Why a 1989 has a different part number versus a 1992 may be triggered by other physical difference instead of electrical.
https://www.fullsizebronco.com/threa...arness.337346/
Some discussion on the model year change over, 1998 vs 1989. Why a 1989 has a different part number versus a 1992 may be triggered by other physical difference instead of electrical.
Fleet Owner
Joined: Oct 2005
Posts: 20,789
Likes: 1,753
From: Kentucky
It would function..for awhile before the voltage spikes from the IAC solenoid coil kills the circuitry inside the computer. When voltage is removed from the coil there is a voltage spike as the magnetic field collapses. This would happen ~300 times every second. I believe the IAC is pulse width modulated with a 300 Hz signal.
Thread Starter
|
Freshman User
Joined: Dec 2020
Posts: 38
Likes: 0
We replaced all of the vacuum lines and replaced the IAC valve to the correct one. The truck started cold at 1200 rpm. Much smoother idle than before. As it ran, the idle climbed over 2k rpm. I unplugged the IAC and the idle dropped.(the old IAC did nothing). With the IAC unplugged, it ran much smoother but the idle fluctuated between 750 to a little over 1000. I need to clear out the codes and see what pops back up. Suggestions where too look next? We are getting ready to get slammed with snow again....I really need a garage!
Fleet Mechanic
Joined: Aug 2015
Posts: 1,835
Likes: 364
From: Candy Mountain
So, just to get it all laid out...
You are working on a 92 F-150, which was originally equipped with a 4.9, but an 89 5.8 has been swapped in, right? Questions - what computer was used?, How was the engine control harness handled? did they use the harness and computer from the 89?
You have done a basic ignition tune up, replaced the vacuum lines, and the IAC to the 89 part? Any other work or modifications? What transmission is in the truck?
Normal cold start behavior includes a high idle for a minute or so to warm things up, normally around 1200rpm. 2000 is excessive.
You are working on a 92 F-150, which was originally equipped with a 4.9, but an 89 5.8 has been swapped in, right? Questions - what computer was used?, How was the engine control harness handled? did they use the harness and computer from the 89?
You have done a basic ignition tune up, replaced the vacuum lines, and the IAC to the 89 part? Any other work or modifications? What transmission is in the truck?
Normal cold start behavior includes a high idle for a minute or so to warm things up, normally around 1200rpm. 2000 is excessive.