3.8 Rough idle problem (any input appreciated) - TCCoA Forums
 
LinkBack Thread Tools
post #1 of 12 (permalink) Old 07-19-2002, 02:35 PM Thread Starter
4th Gear Poster
 
cmd146's Avatar
 
Join Date: Jul 2002
Location: Coatesville, Pennsylvania
Age: 45
Posts: 218
3.8 Rough idle problem (any input appreciated)

I have a 1995 Thunderbird LX, 3.8 NA. Car has 130,000 miles but runs strong. The engine has a noticiable shake about it only while idleing in park or sittng at a light in drive. Step on the gas - it straightens out, and runs great. I've replaced all the normal tune up parts (plugs, distributor cap, rotor, plug wires). I've checked the EGR valve and all EGR related sensors and actuators - they seem to work fine. No computer codes. No apparent vacuum leaks. Vacuum test gauge shows stedy vacuum. I replaced the head gaskets 30,000 miles ago, but it's been doing this shake for the last 20,000 miles or so. It was very subtle at first, but it been getting worse. I did a compression test 20,000 miles ago - it was fine, I'm going to check it again within a week. Any ideas are appreciated!

Thanks in advance.
cmd146 is offline  
Sponsored Links
Advertisement
 
post #2 of 12 (permalink) Old 07-19-2002, 05:25 PM
krusher
Guest
 
Posts: n/a
Had the same problem

Well, actually I have the same problem. I'm still replacing things. Its really funny actually... Each thing I replace makes it idle better but not normal... So far I've replaced in order:
plugs/wires
fuel filter
replaced MAF
intake manifold gasket
cleaned EGR valve
replaced O2 sensors
That's what I've done so far... it still idles a little rough... not stalls though... next thing to replace is the sensor that sends engine temp to the ECC.
post #3 of 12 (permalink) Old 07-19-2002, 05:43 PM
MA Chapter Director

Administrator
 
Rodeo Joe's Avatar
 
Join Date: Jul 2002
Location: Franklin, MA
Age: 63
Posts: 7,969
Garage
Cool

Could be the IAC (idle air control) valve. Real easy to get to on the 3.8, 2 screws on top of the throttle body. People say you can clean them, some say just replace it. Just a thought.

Joe

It's not a 97 Sport, it just looks like one!

Mass. TCCoAers, Send me your info!

I buy all my Ford parts from 93 lx.

Member of the TCCoA Damage Control Team.

R.I.P. Johnny Langton 1975 - 2011
Rodeo Joe is offline  
Sponsored Links
Advertisement
 
post #4 of 12 (permalink) Old 07-19-2002, 07:39 PM
6th Gear Poster
 
Join Date: Jul 2002
Location: North Jersey
Age: 34
Posts: 607
I second what Joe said. My car had bad idle and base timming at idle. It tured out to be the iac.

1993 LX 5.0
JSGAuto is offline  
post #5 of 12 (permalink) Old 07-19-2002, 08:39 PM Thread Starter
4th Gear Poster
 
cmd146's Avatar
 
Join Date: Jul 2002
Location: Coatesville, Pennsylvania
Age: 45
Posts: 218
RE: 3.8 Rough idle problem (any input appreciated)

Thanks for the suggestions. I actually did replace the IAC a few years back tracing down an unrelated stalling problem. But that was about 60,000 miles ago. The idle speed doesn't surge or anything, it stays pretty constant. It feels a lot like a vacuum leak, but I can't find any. Could a bad IAC cause this kind of shake?

Thanks.
cmd146 is offline  
post #6 of 12 (permalink) Old 07-19-2002, 08:47 PM
6th Gear Poster
 
Join Date: Jul 2002
Location: North Jersey
Age: 34
Posts: 607
I would replace the iac. Last week my car developed a shake. It was different feeling from the idle problem, but it is difficult to explain. It turned out to be incorect TV cable setting. So start with the IAC and if that doesnt work, you may want to check the tv settings.
Jim

1993 LX 5.0
JSGAuto is offline  
post #7 of 12 (permalink) Old 07-20-2002, 05:42 PM
6th Gear Poster
 
Alex's Avatar
 
Join Date: Jul 2002
Location: San Francisco
Posts: 604
Send a message via AIM to Alex
This is gonna sounds stupid but, have you tried just adding more oil? I had this problem and all i needed was a little more oil in the sucker and it fixed it.

1991 Mercury Cougar LS (Dead)
1989 Ford Probe LX (Dead)
1989 Ford Taurus SHO (Sold)
1994 Ford Taurus SHO (Dead)
1994 Ford Taurus SHO (Weekend Cruiser)
1999 Honda Accord EX (Daily Driver)
Alex is offline  
post #8 of 12 (permalink) Old 07-22-2002, 07:33 AM Thread Starter
4th Gear Poster
 
cmd146's Avatar
 
Join Date: Jul 2002
Location: Coatesville, Pennsylvania
Age: 45
Posts: 218
Oil level is ok.

Nothing sounds stupid when dealing with a Ford 3.8! It's a very quirky engine, but with proper care it's a good one.

I'll try the IAC. Thanks for the suggestions.
cmd146 is offline  
post #9 of 12 (permalink) Old 07-25-2002, 11:49 PM
 
Join Date: Jul 2002
Posts: 4
Rough running 3.8

I had my 87 Cougar in and spent $2500 trying to find why it runs rough, changed virtually everything. I just discouvered what it is. Go outside where it is pitch black. Wait for 15 to 20 minutes, then (no lights of any sort allowed here so prepare ahead of time to cover or disconnect any that may work) open hood, start engine and peer into engine compartment approximately where you would expect to see the spark plugs, spark plug wires, coil wire, and the coil. Now, take your time and watch for little spikes of electricity jumping to ground. It looks like miniture lightning strikes. If you see any you need to replace the defective part. Mine turned out to be the coil, it must be defective because it is arcing to ground along it's sides, not at where the coil wire is attached at the top. I can see there are one an maybe two of those brand new plug wires arcing too. The engine would run fine for sometimes a week, then go crazy. Not one mechanic could find the friggin problem.
Gary is offline  
post #10 of 12 (permalink) Old 07-26-2002, 12:29 PM
 
Join Date: Jul 2002
Posts: 1,447
have you checked your motor mounts? cause both times my idle was rough, it was from one of the motor mounts going bad. if they are bad, itd be a good idea to switch to solid (rubber or poly) because we have liquids in there as stock and they suck. -greg
glowing escape is offline  
post #11 of 12 (permalink) Old 07-26-2002, 09:29 PM
Seasoned Veteran Poster
 
Tim Groth's Avatar
 
Join Date: Jul 2002
Location: Roanoke, VA
Age: 35
Posts: 935
Send a message via AIM to Tim Groth Send a message via Yahoo to Tim Groth
Engine treatments...

You may have done this, but here's a story....

....My car had a similar problem starting to develope and I'm all scared the headgaskets will let go again so I went to advanced and told them the deal said I wanted some engine treatments just to make sure. Guy sold me this stuff called Sea Foam (at first I was like but it's not in a fancy bottle...) I put it in earlier in the day, drove to work kicked the beast in a few times to get the stuff in the engine, no smells or anything. Came to a light, I couldn't even tell the engine was running(normally the antenna would shake). Got off work tonight, the engine once again ran so smooth that I had no clue i had turned it over. For a while she would kinda chug to turn over and then once started she'd run good as you said.

I also replaced my plugs, wires...ect and come to find out it was just some build up. Let me know how it turns out for you.


here's a link to the product I'm refering to.

http://www.seafoamsales.com/motorTuneUp.htm

Current Collection
1994 Thunderbird SC - Auto

1994 Thunderbird SC - 5spd
1995 Thunderbird SC - Auto
1997 LX - Auto - Parts Car
Tim Groth is offline  
post #12 of 12 (permalink) Old 07-30-2002, 08:05 PM
5th Gear Poster
 
Join Date: Jul 2002
Location: Ottawa,OH
Age: 39
Posts: 377
Send a message via AIM to rzimmerl
have got the same problems, the rough idle is only when the car is warm and go to restart it, after driving like 50 feet runs fine, have already cleaned the iac and the throttle body, think o2s are going bad, is shooting codes put dont have my reader on me when it does. when the light is off the reader doesnt pick up any codes. just lost on what to do. dont really want to go buy parts that dont need. replace head gasket plugs, wires, cap and rotor, o2s 20000 miles ago. any help would be appreciated.
rzimmerl is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the TCCoA Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome