As some of you may know, my DD is a '93 Mustang LX 4 cylinder. It is in pretty good condition, but it is a 16 year old car, so of course it will have its problems.

When the car is running, as in going down the road, it runs great. It's slow, but it runs really good. It idles fine when it is in park. My problem is when the car is idleing in drive. Whenever I have my foot on the brake at a stop light, the idle is pretty damn rough. Like I said, it is obviously an old car so I don't expect it to idle smoothly, but I know it shouldn't be this rough. It's almost like the car is one giant massage machine or something, the vibration is that strong.

I don't feel like it's anything major. There are no weird noises or anything accompanying the idle. The car runs normal, except for the rough idle.

If there is anything you guys think I should check, please let me know.

 

Fuel filter, spark plugs, oil change

 

Can't be any of those. I just did an oil change about 3 months ago and the spark plugs and fuel filter were replaced maybe one year (give or take) ago, as were the spark plug wires and coil packs.

 

Were the 93 4 cyls. EFI or carbed


edit NM use some fuel injector cleaner or seafoam

 

They're EFI. I've heard about seafoam. I'm hesitant to use it because I don't quite understand how to use it, if that makes any sense, haha.

Are there any sensors that might need to be cleaned or something, or is that something the Seafoam would take care of.

 

I can't tell you anything about sensors but I can vouch for sea foam.


I have used it a couple of times on different cars basically you put half the bottle into the oil and half into the gas.

It has always worked for me

 

Val, do you have a tach in the car, if so how many RPM's is it idling at in gear? No offence but dont start with the snake oils yet. Did this just start or has it been doing it awhile? Maybe a bad tank of gas?

 

Yes, there's a tach. I'll have to report back tomorrow with the exact rpm's it's idling at in gear. I'm inclined to say that they're normal 800-1,000 rpm's.

It has been doing it a while, I just feel like the vibration has gotten worse since I've been driving it every day. It's not a bad tank of gas, I know that much.

 

Val, when you check the rpm's, ckeck it in neutral and also in gear OK.
If you could get someone or yourself to take look at all the vaccum lines for brittleness and cracks or maybe some that have come loose.

 

Okay. I'll do that tonight when I get home and let you guys know the results tomorrow morning.

 

I'm back.

It idles at 800 both in gear and in neutral. No cracks or disconnected vacuum lines.

I have also noticed the car idles better the longer it has been running. When I get home from work after about a 25 minute drive, it idles smoother than it did when I first left work. Also, when I start it up to go to lunch, I'll park my car for an hour, and when I start it up to get back to work, it always starts pretty rough. It will kind of stutter after it starts, but then it idles fine. I figured I should mention that while I'm thinking about it in case that could be a contributing factor to my idle problem.

 

Has the EGR valve ever been cleaned since you've had the car? Do you see any smoke when you start the car?

 

I don't know the answer to the first question. I have put it in the shop countless times, so I can look on the records of my invoices to see. There is no smoke when I start the car.

 

Try some fuel injector cleaner

 

I plan to get a bottle this weekend and put it in there the next time I fill up. Even if that doesn't help, it certainly can't hurt it.

 

Yeah it won't hurt it and the all those products are supposed to help with a rough idle

 

Have you had it in the shop for this problem or was it somethimg else?
Try the Lucus brand injector cleaner its about 6 bucks a bottle but its pretty good stuff. Run a tank with this stuff and let us know if there is any improvment.

 

Okay guys, old thread, but I wanted to revive it.

I popped my hood yesterday on my '93 to check my fluid levels, and I heard a small kind of clicking/grinding noise towards the back of the engine. I got down as close as I could and I saw that my EGR valve had a little bit of smoke coming out of it and I'm 90% sure it is what is making that noise. I'm pretty sure it shouldn't be allowing smoke to come out of it, right?

I looked the EGR valve up on the internet and it said that a bad EGR valve can cause poor acceleration and rough idle, both of which I have. I think I'm going to replace it, because as far as I know, it is still running off of the stock one! So replacing it can't hurt any.

 

Good call. i hope that will solve the issue. sounds like thats what it is.