03 4.6L Idle issues

[Farmtruckracer]

Been researching for a while and nothing seems to match my issue, so here goes...

Original issue, while slowing down, almost to stop, idle would drop way down so low it would almost die. Then it got so bad after a day or 2 and it would die. No codes or CEL.
A few sources suggested IAC, so I replaced it. I found a source to check old one with ohm meter and it was out of specs. I performed the KAM erase and relearn. This changed problem to a higher than usual idle when starting,but would drop down after a minute. When coming to a stop, the idle rpm is 1500 until about 1 second after stopping. This makes it tough to stop, then when stopped rpm drops a little below 700 and makes you think it died for a second then to normal.
I also replaced the TPS and no change. Confirmed no vacuum leaks. Checked for codes again and got drive cycles not complete message so I got a list of them and performed all of them. Checked again for codes and none found. I'm suspecting egr valve or the new IAC is bad, But open to more suggestions. Thanks.

 

[matt0248]

Where did you get the replacement IAC from? I got one from auto zone and I did not like the way it idled. I found a motorcraft one on amazon for 45 bucks. This one seems to idle a little better. You should remove and clean your throttle body also and see if that helps.

 

[Farmtruckracer]

The IAC came from Carquest. I really am considering getting one from Ford. I forgot to mention that I also tried a new EGR pressure sensor. The parts guy seemed sure this was it and said I could return it if it wasn't so what the heck. No change tho. The EGR itself does hold vacuum, but I haven't verified the valve part is closed all the way yet.

 

[Rrunkle]

Any luck on is problem? Having EXACT same symptoms on my 03 Limited. Also replaced with an Autozone IAC. Previously had a vacuum leak (year ago) which I fixed. Did full check for vacuum leaks this time, and NONE. Did notice one weird thing: the old IAC which I took out was missing some parts. On the outlet side, there is a brass rod and spring that were completely missing on the old part. Auto zone IAC has these. I should mention that this is the second Autozone IAC that I've tried. The first one hummed like a freight train, and actually did perform worse. Also noted that the first one did NOT include a replacement gasket. The second one included a gasket, and seems to perform much better, not nearly as noisy. But, still stalls at idle about 50% of the time. Also, on the second Autozone IAC, I actually torqued to the correct torque of 10 NM, rather than just guessing by hand. I suspect that I might have been over torquing the first one.

I have not checked the EGR, PCM, or the TPS.

One additional weird note: if i squeeze on the tube coming into the IAC really hard and close it off, it seems to help calm the idle down a bit.

It seems much worse if running the AC.

 

[Farmtruckracer]

I replaced IAC with one from Ford and re-did the KAM again and now its fine, just like new again.

 

[Rrunkle]

Sounds like I'll be looking for a Motorcraft replacement. Based on the poor performance of the first Autozone IAC and the fact that it changed with the new one makes me question the quality and also the compatibility of this part.

Anything special on the KAM procedure? Or, did you just pull the battery for 15 minutes, and drive around afterwards?

Thanks,
Rob

 

[rocco123]

Check this thread....
http://www.explorerforum.com/forums/showthread.php?t=217062

 

[Farmtruckracer]

I did 10 mins battery disconnected, then somewhere online I found to re-learn the KAM, have it idle for a few mins with ac on, them ac off in neutral, then do same in drive.
Not sure if needed or just drive for a while, but it is running great now.
The issue in the link Rocco added happened to me last year and I was able to figure it out pretty quick.
This last issue was tricky since I had no code and had replaced a part with the idea that a new part would be better. I pondered over buying a Ford IAC for quite a few days and finally had to try.

 

[Rrunkle]

Yup. I also had the issue from the other thread. I was able to find that vacuum leak pretty quickly, once I got the noise cover off the engine. The toughest part about that leak was finding the darn part. That thread is a really great resource, and many people have chimed in that they found the same problem.

I think I'm going to give the Autozone IAC a try this week before I call it a loss. It really did make a huge difference once I installed the second one. When I first installed, it ran really rough, but then cycled high and low idle, a couple times, and leveled out. Then, I drove it around the block, and I was smiling like the cat that ate the canary; I thought that I had beat the problem. But, then, as I put the car in park, it stalled. That might have been the first time that I had turned the AC back on also. So, maybe, I'm still working through the relearn process. Either way, it seems obvious that the solution is with the IAC. I'll post on the results.

Oh yeah, my IAC problem hasn't thrown any codes either. Unlike that vacuum tube leak last year, which threw tons of codes.

Thanks much!!!

 

[Rrunkle]

UPDATE: Fixed

Well, after trying a second Autozone IAC, I finally decided to try a Motorcraft part. The Autozone IAC never seemed to be able to calibrate, and much worse with the AC on. It stalled everytime I pulled to a stop and at idle.

The Motorcraft part worked first time, didn't even need calibration time. See pic. Note the one of the left (Autozone IAC) has a brass rod and spring in the bottom bore that the Motorcraft (right) part does not. The one that I removed from the car initially (OEM) was like the one on the right. I thought that maybe the old one was missing parts though, hence the initial problems.

So, needless to say, the Autozone part IS NOT COMPATIBLE with my 2003 Explorer. This is just sad.

 

[rocco123]

We appreciate the update. Feedback on a final fix helps everyone.

 

[Hotwire00]

High Idle with Autozone IAC's fixed with Motorcraft

I had the same problem, the Autozone IAC's are not compatible with my 2003 Explorer 4.6L. With the Autozone IAC's I had a high rpm when stopping requiring additional brake effort. After finally stopping, the idle would snap to normal, around 700 rpm.
Rrunkle, thanks for your posts, you really gave me the confidence to try the third (Motorcraft) IAC that fixed it. I'd like to note that the Autozone IAC's were about $83. The Motorcraft from the Ford dealer was $170.

 

[home4sale2]

My IAC valve does not have a brass rod at all...could that have broken off or were there versions of this valve that looked different than either of the two pics? I have a 2002.

 

[2008PHANTOM]

Whats the part# for the ford IAC?

 

[SyberTiger]

I know this is old thread but I thought I'd tack on some useful info just in case someone stumbled across this old thread.

CHECK OUT THIS THREAD for a solution that goes beyond replacing the IAC.

The Ford short number for the Motorcraft part is CX1785. At can be purchased on Amazon for around $75. The local Ford stealership wanted around $195.

 

[Stelvio]

THANK YOU Rrunkle!!!!
I had an idle problem, kind of rough. I cleaned my MAF, re-gapped the plugs, and checked vacuum lines. Afterwards, it ran better. A day later, the idle was WAY too low, in fact, the engine would die while coasting or sitting at stop signs unless I two-footed the pedals to keep it running.

I bought a BWD IAC from O'Reilly's and noticed that there was no shaft in the original. I assumed it had somehow disappeared (though couldn't quite figure out where it could have gone to). I installed it and it ran wonderfully for a day, then the idle climbed up to 1,500. Gas mileage dropped to an average of 12.5.

Rrunkle's post confirmed for me that there was not supposed to be that additional shaft (or plunger), and that the box-store BWD brand IS NOT COMPATIBLE with the Motorcraft for the 4.6-liter Ford V-8. I found the correct Motorcraft IAC at Amazon for $75, which was the same price as the BWD. (While the box stores will order the Motorcraft for you, they charge upwards of $160.)

I installed the Motorcraft and the engine now purrs like a kitten, and the gas mileage on my test drive read 18.4 (city).!!!

Again, thank you Rrunkle!!

 

[Rrunkle]

Very good!

 

[davidmmm69]

THANK YOU Rrunkle!!!!
I had an idle problem, kind of rough. I cleaned my MAF, re-gapped the plugs, and checked vacuum lines. Afterwards, it ran better. A day later, the idle was WAY too low, in fact, the engine would die while coasting or sitting at stop signs unless I two-footed the pedals to keep it running.

I bought a BWD IAC from O'Reilly's and noticed that there was no shaft in the original. I assumed it had somehow disappeared (though couldn't quite figure out where it could have gone to). I installed it and it ran wonderfully for a day, then the idle climbed up to 1,500. Gas mileage dropped to an average of 12.5.

Rrunkle's post confirmed for me that there was not supposed to be that additional shaft (or plunger), and that the box-store BWD brand IS NOT COMPATIBLE with the Motorcraft for the 4.6-liter Ford V-8. I found the correct Motorcraft IAC at Amazon for $75, which was the same price as the BWD. (While the box stores will order the Motorcraft for you, they charge upwards of $160.)

I installed the Motorcraft and the engine now purrs like a kitten, and the gas mileage on my test drive read 18.4 (city).!!!

Again, thank you Rrunkle!!

So the iac brought your mileage up from 12 to 18??? Quite amazing

 

[KAS-PA]

Had the exact same issue.. I returned the Autozone crap.. They had an OEM, HITACHI part number ABV0010 which was 21 bucks more, it totally resolved my issue and the idle is perfect now.