How Rough Should A Stock Fox Run?

[2007_Crown_Vic]

Hi Guys,

Should a stock foxbody run fairly smooth? My 1990 GT had a bit of a bounce idling at red lights. Don't get me wrong, I love the old big block muscle cars with carburetors that ran like that but seemed odd that a basically stock injected 302 would have any of that.

Tonight after work I went and changed the PCV and cleaned that screen assembly that is under it. Then I changed the cap and rotor. I didn't think this would really change the way it ran at all, I was just trying to get to all the routine maintenance items done because the car has sat for so long and I have no idea when (if ever) they were done.

To my surprise, when I fired the car up and did the test drive, that bounce is almost all gone and it is noticeably smoother.

The PCV valve appeared to be original but the piece inside was still moving freely, and the screen piece was dirty but really didn't look that bad. The cap and rotor I took off had some build up on the terminals but again, didn't look that bad. I was just really surprised that the two made such a difference.

 

[mikestang63]

like any other stock motor, it should run smooth

 

[5.0specialist]

Hi Guys,

Should a stock foxbody run fairly smooth? My 1990 GT had a bit of a bounce idling at red lights. Don't get me wrong, I love the old big block muscle cars with carburetors that ran like that but seemed odd that a basically stock injected 302 would have any of that.

Tonight after work I went and changed the PCV and cleaned that screen assembly that is under it. Then I changed the cap and rotor. I didn't think this would really change the way it ran at all, I was just trying to get to all the routine maintenance items done because the car has sat for so long and I have no idea when (if ever) they were done.

To my surprise, when I fired the car up and did the test drive, that bounce is almost all gone and it is noticeably smoother.

The PCV valve appeared to be original but the piece inside was still moving freely, and the screen piece was dirty but really didn't look that bad. The cap and rotor I took off had some build up on the terminals but again, didn't look that bad. I was just really surprised that the two made such a difference.

Replace the spark plugs with motorcraft ASF42C copper plugs, and if the ignition coil looks old, replace it. Mine began idling on the choppy side and I replaced with a motorcraft replacement coil. Not only did the idle smooth out completely, but the car felt more alive. There was a definite increase in power. I think the coil was the original 91' coil. lol

 

[2007_Crown_Vic]

Good to know. The coil and plugs were already on my list anyway. Next time I place a Rockauto order I will add those. Or maybe see if LMR has them. I want to do the subframe connectors too and Rockauto doesn't have them.

It is really nice to get a car in as good of shape as this one due to it sitting for so long, but it seems what you get in the body being in great shape and low mileage, you pay for in the things like suspension and routine maintenance that has gone over looked for so long.

 

[sal5.0]

In my opinion... Nothing compares to stock/factory as far as driveabilty, and being reliable. It should run very smooth as long as everything is operating the way it should the day it rolled out of the assembly line.

 

[stpete]

There's a bunch of common things that cause a rough idle. Google "Mustang Surging Idle Checklist" and follow that. My car took a lot of effort as just about every step helped. I eventually got it idling perfectly cold and hot. You started off right, I think the checklist assumes you started by doing a basic tune up.

 

[General karthief]

No where here have I seen that you looked for codes, codes can be present without the check engine light on.
https://www.stangnet.com/mustang-fo...codes-from-eec4-in-86-95-5-0-mustangs.889006/
This will tell you how to pull codes, another link is the surging idle check list, a lot of people contributed to these help threads and they work, just follow the directions and you'll be running smooth again.
http://forums.stangnet.com/showthread.php?t=698148