rrobello

Check engine light came on, ran the code and it came up P0506 -Idle Control System RPM Lower Than Expected.

So my questions are:

what the hell does that mean exactly?

when I take it to Ford should i reflash the comp back to stock beforehand?

and how serious is this problem? if I cant take the car in until Monday or Tuesday is it ok to drive just to and from work which is about a 10 minute drive each way?

thanks for any input!

SixtySix

Try raising the idle rpm yourself a little bit and see if it comes back. I know while my A/C is running in the summer the idle goes about 200 RPM's lower than what it usually is. Maybe that was enough to trip the code

GottaHaveIt

if you have a tune in and a differnt grade fuel I think it could , I would reload factory tune back to see first and even before you take it in or if you get it back and they reflash you your Hooped keep at factory and when get back check first before any upload just incase they changed it ? if they did tell your vender whats up and your engine was reflashed to get a new code.

GottaHaveIt

or just maybe your Mustang is Transforming to an Autobot and miss's the babe's that are usually sitting on your car, kinda like Viagra for a car ?

rrobello

well last night after work I got into the car and started it up, check engine light gone and car running fine, still is today. Ill keep an eye on it to make sure nothing fishy happens and will check it out just to make 100% certain.

Incase anyone has a similar issue I found this about trouble code p0506

Louie

I had the same code come up this week for the first time ever. So far I could only link it to filling up at a different gas station than usual (Shell vs. BP). I cleared the code and reloaded the tune, but it came up again. After I re-flashed back to stock it went away. I'll try to drive down to min. fuel level and fill up with BP gas again, see what happens.

rrobello

my friends been having the same exact issue for a couple weeks now

the other day my light came back on, was near empty so I was going to run it empty and reflash it back to stock and put 87 in, but that night the light went away. There has to be a TSB on this. Anyone???

rrobello

well flashed it back, been having major issues now, the car shut off a couple times at full speed, the idle just went to 0 and it stalled even with my foot on the gas. and the other day on the freeway I had it up to 80mph and it was reving higher than it normally does and when I took my foot off the gas it held the rpms there and didnt slow.

taking it in tomorrow to Ford to see what the problem is.

kh765

Are you back to stock now? Good luck with the fix...

rrobello

just got off the phone with Ford they claim it was dirty intake and TB, I know it wasnt the intake as I cleaned that when I first found out what the problem was and checked to make sure the tube wasnt clogged. The TB could explain normal idle problems and the car dipping in idle at a stop, but the recent stalling at 60+mph? I dont think so, but we will see.

HolyPony!

On my car it was the throttle position sensor in the TB. They unfortunately have to change the whole TB for that. My car, a very early 2005, has been running like sh*t ever since I got the car, but this is now fixed and now the car runs beautifully ! The dealer would not respect the warranty because the car is modified (Steeda CAI & SCT2 flash) but in my mind it was still worth it

rrobello

I already had that sensor replaced under the TSB a while back; thought this couldve been related.

And thats BS to void your warranty, neither the tune nor the intake would effect the TB and they had a TSB on them, so obviously its a Ford problem, I wouldve fought that.

HolyPony!

You are correct. However this was the only solution to get my car back quickly. I intend on following up this matter directly with Ford

Louie

1 month later (see my post #6 above) and I still have this problem. I've tried everything: removing the CAI and flashing back to stock, adjusting the rpm levels with the XCal2, loading a brand new tune, reinstalling the stock mufflers (while trying to rule out a clogged/restricted Flowmaster muffler)... nothing! I noticed that, as soon as the engine warms up to normal, the rpms drop to as low as 500 when I stop for a traffic light while in gear (car is auto).

So, taking into account the possible causes listed in Richard's post #5 and the issues reported by others, it's most likely the throttle body. The car is out of warranty and it's an easy part to replace, so I'm thinking of ordering it and installing it myself. However, I was wondering: is there any reason why I should install a larger TB at this stage, considering that I plan to keep the car N/A for a few more years? If yes, BBK or Granatelli?

Thanks!

theedge67

Did you try cleaning the TB? I had a very similar problem and I just took a rag and wiped off all the black gunk I could off the inside of the butterfly area on the TB. Totally cured the problem.

Louie

Do you mean behind the valves? Not yet, just what was visible in front of them.
I'm not sure, but I think I read here somewhere about somebody having purchased a TB cleaner spray. Do you remember something like that or what brand it was?

theedge67

Yeah, I remember that. But I just wiped what I could get to both in front and behind the butterflies. I took the whole TB off so I could get to both sides, it was super easy. Just a few bolts if I recall correctly. I didn't use any spray, just a clean towel. The black gunk came right off with some firm rubbing, and it totally solved the problem. No more strange idling.

Louie

EDIT: wow, I did not expect what I found behind the butterflies! It was a thick, black gunk indeed, which came off easily with a soft rag. I flashed the JLT2 tune again, with Doug's standard idle parameters and drove to work with no issues so far. Usually the CEL would come on after 5 miles or so lately. Fingers crossed!

Infinity

Bumping this. Has anyone had the problem come back after cleaning? Mine did, but only once. I've never had a code pop or the CEL come on, but it has died a couple of times when depressing the clutch. Really odd. Maybe I didn't get it good and clean? If I were to insist on a new TB, would that solve it, or only last until it gunks up again?

rrobello

it doesnt take much dirt to make this code pop up, I cleaned my buddies and it was hardly dirty but after wiping it down with some carb cleaner and sticking back on the code went away and never came back, but if it keeps it up take it to Ford and have them figure out whats really wrong with it, there was a TSB for the sensor a while back, I had that replaced on my car