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Topic: Rough Idle on 88' 3.8L (Read 1589 times) previous topic - next topic

Rough Idle on 88' 3.8L

I started driving my Cougar as my daily driver a few weeks ago. As expected the car is started to reveal some issues that probably developed from it sitting for a long time. I've already replaced the radiator, U joints, thermostat, fuel sender and seat belts. I thought I was in the clear and started driving it long distances. Yesterday on the way home I pulled off the highway and as I sat at the intersection I noticed a rough idle that wasn't there before. It is a consistent "wobbling" back and forth type of idle and the engine only feels off when the car is stopped and idling. I checked vacuum lines today and found the tube coming off the intake plenum had worn a little from rubbing on a bracket but it hadn't worn through. I taped it up anyway but that made no difference. Everything else looked normal. Throttle body was clean, and no other strange noises. Any ideas on what else to check?
1988 Mercury Cougar LS
5.0HO + T5 Swap + Suspension/Brake Mods

Rough Idle on 88' 3.8L

Reply #1 –
Run codes. If nothing comes up, double check all the vacuum lines and try a base idle reset.

Prretty much only the iac and tps really effect idle, but certain other codes can change how the computer compensates at idle, so do that first.
Quote from: jcassity
I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
Hooligans! 
1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
1986 cougar.
lilsammywasapunkrocker@yahoo.com

Rough Idle on 88' 3.8L

Reply #2 –
Do you mind giving me a brief run down on how to check the car's codes?
I'd certainly appreciate it!
1988 Mercury Cougar LS
5.0HO + T5 Swap + Suspension/Brake Mods

Rough Idle on 88' 3.8L

Reply #3 –
https://www.youtube.com/watch?v=z0ehA8cFTkc key one engine off self test.
https://www.youtube.com/watch?v=9QSiS6wf7oU key on engine running self test.
video of me running codes on my 87 tbird, I show you what to look for, how it works and what to hook up. sorry for the cruddy video.

http://sbftech.com/index.php?/topic,849.0.html
a quick web page to browse so that you can see what you need and what the codes mean.

base idle reset instructions.
http://sbftech.com/index.php/topic,1031.0.html

if ya get stuck or need any help, let us know and we should be able to help you. Since you have a 88 3.8 all the procedures should be pretty much the same as all the instructions for a 5.0. One thing I do when I run codes, I take a video of the flashes so I can refer back to them later.
Quote from: jcassity
I honestly dont think you could exceed the cost of a new car buy installing new *stock* parts everywhere in your coug our tbird. Its just plain impossible. You could revamp the entire drivetrain/engine/suspenstion and still come out ahead.
Hooligans! 
1988 Crown Vic wagon. 120K California car. Wifes grocery getter. (junked)
1987 Ford Thunderbird LX. 5.0. s.o., sn-95 t-5 and an f-150 clutch. Driven daily and going strong.
1986 cougar.
lilsammywasapunkrocker@yahoo.com

Rough Idle on 88' 3.8L

Reply #4 –
Thanks man! Ill try it out tonight if I have time or tomorrow and post the results
1988 Mercury Cougar LS
5.0HO + T5 Swap + Suspension/Brake Mods
 

Rough Idle on 88' 3.8L

Reply #5 –
Would a code 41 indicate I have a bad O2 sensor?

This is what the code reads:

41 - System Indicates Lean -passenger side(R), No o2 Sensor Switching Detected. always lean -passenger side(M)
1988 Mercury Cougar LS
5.0HO + T5 Swap + Suspension/Brake Mods