Mustangsz

I got a 02 Mustang 3.8L 5speed with 248K and since i had the car it always did this weird idle the odd time or if i put my windows up or down my rpms will drop to 400-500 but it never stalls also if i rev my car up to say 1500 rpms and let it drop once it goes by 900 rpm it will make this rattle noise its hard to explain and i tried getting a video but cant hear anything.. anyone have any ideas? i cleaned the throttle body about a month ago car has a intake and exhaust also has a bad power steering pump if that has anything to do with that... no check engine lights and cant find anything on scanner.. thanks

yiannisthegreek

Hmmmm...

I have a bit of a similar issue as of late but mine only seems to do this when I use my rear defroster while I am driving the car. I also only noticed this started after I had my clutch work done which I find a bit odd.

I have good idle (800 to 900 RPM) 99% of the time while driving (except for the occasional jump / miss I can feel every now and again, not sure what THAT is cause I have NO codes of any kind) but when I turn on the rear defrost and say come to a red light, the car drops idle to about 500 - 600 RPM and almost feels like she wants to stall but it never does and as soon as I turn OFF the rear defrost it jumps back up to regular idle.

It seems like a "drain" on the charging system almost.

As for the rattle noise, is your car a Manual or Auto? If Manual, it sounds like it could be your Throw Out Bearing. This is one of the reasons I took my car in for clutch work.

I wish I could help you and I hope someone here can cause then maybe it would help me as well.

Anyone, any ideas?

Mustangsz

Mines a manual and I can hear it in neturial so I xcouldnt were it being my clutch.. It does seem like its losing voltage does urs drop when you roll there windows up? .. Im also part Greek to.. Haha

yiannisthegreek

Ha ha ha... Nice. A fellow Canadian AND Greek... :-)

Does the sound go away when you put slight pressure on the clutch pedal? That is exactly what mine was doing and it was definitely the TOB (throw out bearing). Id be willing to put money on it. I also had the same rattle / knocking sound if I reved up the engine and let it come to rest at idle.

Mine does drop EVER SO SLIGHTLY when using the windows or anything electric really but I really notice the "weird idle" when Im driving and need to use the rear defrost. I could be idling PERFECTLY (800 - 900) while stopped at lights or whatever and then all of a sudden if I turn on the rear defrost and come to a complete stop the RPM drop to about 500 but never actually stall out. Its weird.

Also it seems that this happens to me when the car is WARM. It is not as bad or does not seem to happen at all when the car is COLD. Again... Weird!!!

You? Is yours persistent ALL the time?

Mustangsz

I find my clutch Taps and I can feel it slightly wen I rest my foot on my clutch and wish I cud find the idling issue its a pain mine also does it with rear defrost

yiannisthegreek

Ya... It definitely sounds like a TOB or even the Pilot Bearing as far as the clutch goes. Do you know when it was last serviced?

And ya, I agree... Mine is becoming a bit of a pain as well. It happened again this morning on way to work. When car was cold / warming up I was running the rear defrost and had no issues. Once the car was at Operating Temp (needle in the middle of the gauge) I had to put the rear defrost back on and the next light I stopped at the car dropped to 500 RPM and felt like it was gonna stall (but it NEVER does) so I just turned it iff and like magic the RPM raised back up to 800 or so.

Its very weird... :-(

Daehawk

Alt giving plenty of juice?

Mustangsz

does yours also do it if you roll up your window? i never checked my alternator yet but my power steering pump is bad do you think this has anythin to do with it? and my pulley is marked up abit

yiannisthegreek

I dont seem to have any other issues with it so I can only assume that my alternator is good and charging everything properly... ???

Mustangsz

i asked my insturctor at school today bc he was a red seal mechanic for 40+ years , he said
it is normal because when yoru using rear defrost and your windows it will draw the power from the motor causing some idling fluxerating , he explained it much better lol he said its nothing to worry about though.