P1506

[Lovemyser]

Hey guy's, can you help...again! lol! Searched the forums about my problem, no luck.

I have a 2000 Merc Mountaineer 2WD 4.0 SOHC

I recently had the common cold start stumbling problem so I decided to clean the IAC, cleaned it with CRC, dried, lubed it with WD40, and manually moved the piston back and forth. The problem went away, thank goodness! Well, later this afternoon I was driving and the SEL/MAL light came on, I promptly drove to autozone and had the code read.

The code was P1506 - Idle Control Speed error. The truck is not acting up in anyway, it drives fine, or seems too. Do you think I ruined the IAC when i cleaned it? Or could it be something else?

Help!

Andy

 

[Runnin'OnEmpty]

Andy, theP1506 is an IAC 'Over' speed error. I suspect that the back and forth movement when cleaning the IAC has something to do with this code.

I'd erase the code and see if it returns. If it does, then I'd just replace the IAC.

ROE

 

[Lovemyser]

Hey, Thanks for the input ROE.
Actually the first time autozone ran the codes, they accidently erased the codes. So I drove it around again until the code came back on, it did, and that's what I got. Is there any other problem that it could be?
I really need to sell this truck...

 

[Runnin'OnEmpty]

Andy, I based my previous post on the fact that you moved the IAC plunger back and forth just before that specific code appeared. I suspect that may have gotten the adjustment off somehow, and now the PCM sees the IAC as needing a signal that is out of range to stabilize the idle.

There's probably a way to fix this by taking the cannister side of the IAC apart, but I've never disassembled one so can't advise....

If you don't want to buy a new IAC just yet, try removing the battery cable for about 15 minutes. This might reset the parameters and turn the light off. Also double check the IAC electrical plug; maybe spray the connectors with WD-40.

Good luck,
ROE

 

[Lovemyser]

Thanks for the advice, I'll try those options.

 

[Lovemyser]

ROE, I did exactly as you said. I purchased a new IAC and installed, while leaving the negative battery terminal off so that the computer would reset the codes. After about 30 minutes of driving, the service engine light kicked on again. It was the infamous P1506, so I got some dielectric grease and lubed the terminal, hopefully it won't kick on again...what do you think?
I just sold it so I hope it doesn't do it again.

 

[Runnin'OnEmpty]

Andy, that's a strange one. I was sure a new IAC would cure it. Our OBD II Explorers have an 'adaptive learning' strategy built into the PCM, that adjusts for wear on sensors and engine parts. The only thing I can think of is that maybe the idle parameters still haven't adjusted for the new IAC...?

If this is true, then the code will eventually resolve itself. It takes about 70 start cycles for the PCM to fully adjust for changes.

So you're out of the Explorer/Mountaineer business.....good luck with your next vehicle.

ROE

 

[BigZac]

P1506 with new IAC and other probs

Well I was missing on all 6 cylinders at one point... lol... if the computer has a cumulative memory. If it doesn't, I don't know how I was driving if all 6 were missing.

I changed all 6 plugs and wires. I figured at 137k, I would throw a new IAC in too. I did, and CEL went away for a few days, only to return on the fourth day. I get P1506. I'm thinking it may be a bad part, and O'Reilly has offered to warranty it out, but is it really true that it takes 70 start cycles for the IAC to learn how to behave? I've started more than 70 times. I have a very high idle (between 1500 and 2000). I also have a loud clicking noise coming from the engine (not regularly... maybe once a week).

Any ideas on both problems? Should I get a new IAC while under warranty? What about the clicking? Anyone know about that? Thanks