Hey all, Very new to these forums (about 3 minutes, heh). I've been very bad in terms of keeping a decent maintenance schedule on my '05 GT but am working on getting things right and enjoying learning how to take care of things myself. The original battery died the other day, and after replacing it and following the instructions in the manual to let the computer re-program, it seemed like the idle is way too low. I got a check engine light, trouble code was for idle low RPM. When driving, if the air conditioning is on, when I come to a stop, about 1/5 of the time the engine stalls. Another 1/5 of the time, it dips low (400ish rpm?) and then goes up to about 1800rpm, and settles around 600rpm. The rest of the time, it dips low (400ish rpm) and goes up to about 7 or 800rpm, and then settles around 600rpm. If the air conditioning is off, it never stalls, but...it's hot, and I'd much rather appreciate driving with the a/c. This has been going on for two days. After doing some research, I came across this thread: http://www.stangnet.com/mustang-forums/626583-surging-idle-checklist.html I didn't know how much of it was appropriate, since it's a different engine and an older model, but figured I'd give at least cleaning the throttle body and the MAF sensor a try first, since they seemed easiest and from what a friend was telling me, likely causes. On top of that, I plan on replacing the air filter, fuel filter, and spark plugs in the very near future. Any other suggestions from that page, or things I can ignore from that page, to try and get this fixed myself? Thanks!
Two days but how many key cycles?? It will take anywhere from 10 - 20 key cycles for the PCM to relearn, however I do also have some bad news it seems that when the battery dies on these cars some times it gives the PCM a brain fart and they need to be reflashed with an OEM program this sounds like you may need to do this.
Well, looks like cleaning out the throttle body, cleaning off the MAF sensor, and unplugging/reconnecting the battery fixed it. I'm idling at 750 even with the A/C on, and no dips when i come to a stop any more. After 10 miles, no changes.
i would venture a guess it was just that it finally re-learned and thats what fixed it after you disconnected the battery again, but the other maintenence you did is good stuff anyway
Some cars are more prone to that than others. My car, '06, has never had an idle problem after any reflashes or the battery change/disconnect. It's in the owners manual that after doing such, the computer must relearn the idle and other related data. After hooking up the battery, start and let the car idle for a couple minutes with the heat/ac off. Then turn the ac on max and let it idle for another couple minutes. That should do it, if the car ran fine/great before the battery disconnect.
