5.0 Rough Idle

89-5.0Fox · February 6th, 2012, 09:05 PM

I have a bone stock 89 LX Hatch with the 5.0. So almost every single time I start it up it does the automatic idle up but then instantly drops to like 400-500 rpms and then goes back up and idles up and down untill Its driven a little bit or unless I hold it at like 1000 rpms for a bit then it seems to do alright. It seems like it just does it when I first start it up. Any ideas?

Ninety3Coupe · February 6th, 2012, 09:15 PM

I could be wrong, but clean the TB? (Hint: using carb cleaner is not recommended by Ford due to a coating on the metal - disregard this tip at will - many do - myself included).

TPS sensor?

IDK, anyone else?

89-5.0Fox · February 6th, 2012, 10:24 PM

So just take the Throttle Body completely off? Do they make like a throttle body cleaner?

Ninety3Coupe · February 6th, 2012, 11:03 PM

Pull the intake leading to the TB, and spray the inside of the TB down with (yes they make it) TB cleaner. Open the blade and get in there with a rag or the like and spray away. Removing it is the best way to clean the back of course, but start with the easy way. If you do leave it on the car, wedge a long (so as not to drop it in there) stick to wedge the TB blade open for 30 minutes or so to allow it to evaporate and then start her up.

At least that's how I do it...

FastStang91Lx · February 6th, 2012, 11:22 PM

Also, pull off your idle air control valve (IAC) off the throttle body and clean it out as well. It is also possible that your IAC is shot too.

89-5.0Fox · February 7th, 2012, 10:09 AM

Alright I'll try it tonight and see what happens. Thanks a bunch!

Ninety3Coupe · February 7th, 2012, 11:03 AM

Good call Fast. Can't believe I forgot that. Lol

Sent from my Autoguide iPhone app

February 6th, 2012, 09:05 PM	#1
89-5.0Fox Newbie Join Date: Jan 2012 Posts: 16 iTrader: 0 reviews	5.0 Rough Idle I have a bone stock 89 LX Hatch with the 5.0. So almost every single time I start it up it does the automatic idle up but then instantly drops to like 400-500 rpms and then goes back up and idles up and down untill Its driven a little bit or unless I hold it at like 1000 rpms for a bit then it seems to do alright. It seems like it just does it when I first start it up. Any ideas?

February 6th, 2012, 09:15 PM	#2
Ninety3Coupe I need a 5 lug kit 1993 Mustang LX 5.0 Join Date: Feb 2012 Location: Anaheim, Ca. Posts: 336 iTrader: 1 reviews	I could be wrong, but clean the TB? (Hint: using carb cleaner is not recommended by Ford due to a coating on the metal - disregard this tip at will - many do - myself included). TPS sensor? IDK, anyone else? __________________ Half of Maximum Motorsports Catalog, Full Intake, Full Exhaust. Needs paint and $35,000 in mods. Car / Build Photos: http://photobucket.com/CoupePictures

February 6th, 2012, 11:03 PM	#4
Ninety3Coupe I need a 5 lug kit 1993 Mustang LX 5.0 Join Date: Feb 2012 Location: Anaheim, Ca. Posts: 336 iTrader: 1 reviews	Pull the intake leading to the TB, and spray the inside of the TB down with (yes they make it) TB cleaner. Open the blade and get in there with a rag or the like and spray away. Removing it is the best way to clean the back of course, but start with the easy way. If you do leave it on the car, wedge a long (so as not to drop it in there) stick to wedge the TB blade open for 30 minutes or so to allow it to evaporate and then start her up. At least that's how I do it... __________________ Half of Maximum Motorsports Catalog, Full Intake, Full Exhaust. Needs paint and $35,000 in mods. Car / Build Photos: http://photobucket.com/CoupePictures

February 6th, 2012, 11:22 PM	#5
FastStang91Lx I Post Entirely Way Too Much 1991 Mustang LX 5.0 Join Date: Jan 2010 Location: Minnesota Posts: 5,572 iTrader: 2 reviews	Also, pull off your idle air control valve (IAC) off the throttle body and clean it out as well. It is also possible that your IAC is shot too. __________________ Point made in less than a few hours with minimal response. http://www.moddedmustangs.com/forums...ml#post4465184

February 7th, 2012, 11:03 AM	#7
Ninety3Coupe I need a 5 lug kit 1993 Mustang LX 5.0 Join Date: Feb 2012 Location: Anaheim, Ca. Posts: 336 iTrader: 1 reviews	Good call Fast. Can't believe I forgot that. Lol Sent from my Autoguide iPhone app __________________ Half of Maximum Motorsports Catalog, Full Intake, Full Exhaust. Needs paint and $35,000 in mods. Car / Build Photos: http://photobucket.com/CoupePictures

February 6th, 2012, 10:24 PM	#3
89-5.0Fox Newbie Join Date: Jan 2012 Posts: 16 iTrader: 0 reviews	So just take the Throttle Body completely off? Do they make like a throttle body cleaner?

February 7th, 2012, 10:09 AM	#6
89-5.0Fox Newbie Join Date: Jan 2012 Posts: 16 iTrader: 0 reviews	Alright I'll try it tonight and see what happens. Thanks a bunch!

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