shaky at low RPM, please help!

[ian7654]

today my car started shaking at low RPMs i can hear a difference in the exhaust too. am i miss firing? could a spark plug have backed out maybe? it gets smoother as the revs climb, but i can still hear a difference in the exhaust. any ideas? i am praying that it will go away, but i don't want to leave it alone and let it get worse.

this isn't very specific i know, but any advice would help. thanks!

 

[ian7654]

bump

 

[Dark Knight GT]

How many miles are on the vehicle ? Also, have you had the SES light yet ? Off the top of my head, I don't know for sure what the problem is, but it could be a slight exhuast leak. I would double check my exhuast just to be sure.

 

[timeless2]

IAC?

 

[ian7654]

94,XXX miles on her. no service engine light. the exhaust does smell more like gas (unspent fumes?).

what is IAC? maybe that's a dumb question. thanks for the help.

i'm gonna take her ot a garage saturday and hopefully not get screwed over.

 

[timeless2]

94,XXX miles on her. no service engine light. the exhaust does smell more like gas (unspent fumes?).

what is IAC? maybe that's a dumb question. thanks for the help.

i'm gonna take her ot a garage saturday and hopefully not get screwed over.

Idle Air Control valve. It controls the air/fuel mixture and flow that makes up your idle speed. Do you have any codes pulled on it? Head to Autozone and they'll scan it for free.

 

[Dark Knight GT]

94,XXX miles on her. no service engine light. the exhaust does smell more like gas (unspent fumes?).

what is IAC? maybe that's a dumb question. thanks for the help.

i'm gonna take her ot a garage saturday and hopefully not get screwed over.

You could be running a little rich.....but if were anything serious, I'm pretty sure you would get the SES light. As I said before, you may have an exhuast leak. I would double check just to make sure. It wouldn't hurt to clean the IAC either, as that sometimes relieves the problems.

Note: There are tons of threads concerning the IAC, and if you do a search, I'm sure you will come up with some of them. The IAC is a little shiny valve attached to the front of your upper intake, and it has one hose that leads to your induction tubing, and has an electrical connector to it as well. It is held to the upper intake elbow(that little part with the horse on it) by two small bolts.

 

[timeless2]

You could be running a little rich.....but if were anything serious, I'm pretty sure you would get the SES light. As I said before, you may have an exhuast leak. I would double check just to make sure. It wouldn't hurt to clean the IAC either, as that sometimes relieves the problems.

Note: There are tons of threads concerning the IAC, and if you do a search, I'm sure you will come up with some of them. The IAC is a little shiny valve attached to the front of your upper intake, and it has one hose that leads to your induction tubing, and has an electrical connector to it as well. It is held to the upper intake elbow(that little part with the horse on it) by two small bolts.

ian7654:
Here is a pic of its location (this is from a Bullitt, but you get the idea):

 

[ian7654]

thanks guys! just got back from a mid-term so i had that on my mind all day. i'm gonna go check this out beore i head to work. i guess i'll drive over to autozone tomorrow.

sorry about asking an old question, i don't want to be a super noob. thanks again

 

[timeless2]

Don't worry about posting questions. Everyone was there once.

 

[ian7654]

it all looks like it's there, but i do remember the guy i bought it from mumbled something about having the idle lowered. maybe that has something to do with it...

off to work for now.

 

[hognutz]

Check for vacume leaks cracked lines etc, IAC will cause you idle to hunt as happend to me but I am not sure if it will make it rough. plugs are easy to pull if you have a little magnet tool. if you know how to read plugs that would let you know if one of them was not buring correctly. make sure the plenum and tb are snug a

I am not sure if the plugs have been changed but at 94k if they have not I would just do it as preventative. I did mine at 61k. they were all firing but the electrodes showed significant wear. I was hunting down a smell in my exhaust. the plugs and air to oil separator in my pcv line did help it.

my rule of thumb is I am too cheap to pay shop rate so start simple and work you way up with advice from people.

 

[ian7654]

my rule of thumb is I am too cheap to pay shop rate so start simple and work you way up with advice from people.

i like that rule


ran pretty smooth on the way home from work, but i don't think the shake is gone. maybe this is the car gods telling me to clean out my engine bay

 

[topless98gt]

i like that rule


ran pretty smooth on the way home from work, but i don't think the shake is gone. maybe this is the car gods telling me to clean out my engine bay

Be careful when you clean out your engine bay...I did that today and my car STARTED shaking at low RPMs. I'm a little concerned.

 

[ian7654]

Be careful when you clean out your engine bay...I did that today and my car STARTED shaking at low RPMs. I'm a little concerned.

really? i'm pretty sure i won't mess anything up, i'm just wiping dust and dirt off.

 

[topless98gt]

really? i'm pretty sure i won't mess anything up, i'm just wiping dust and dirt off.

Oh, I sprayed the whole thing down

 

[ian7654]

Oh, I sprayed the whole thing down

oh. well i hope you didn't mess anything up. one of my friends told me i could just spray it off with a hose. i didn't think that sounded right...

 

[topless98gt]

http://forums.stangnet.com/showthread.php?p=5616043

They said I just got water in the coils and it's arching. I'm gonna do that night test tonight to see.

 

[lover]

I had that problem in my 89GT. It would shake at low rpms, but would taper off a little a higher rpms. It was a fouled spark plug. One little fouled spark plug made it feel like it was something major.