5.0L (1979-1995) Mustang Technical discussions on 5.0 Liter Mustangs within. This does not include the 5.0 from the 2011 Mustang GT. That information is in the 2005-1011 section.

1992 5.0 Rough Idle (No CEL, after tuneup)

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Old 05-13-2012, 07:18 AM
  #1  
senatorsfc
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Default 1992 5.0 Rough Idle (No CEL, after tuneup)

Hi everyone,

I have an issue with my car and I am wondering if anyone here can point me in the right direction.

Car needed a lil' tuneup, so I changed the following today :
Spark Plugs
Spark plug wires
Rotor Cap
Rotor
Ingnitor

Once I was done, I started up the engine. It ran fine for the first minute and then it started to bog and moan, almost stalling.

I quickly made a video to show what happens. (Can't really hear the engine...didn't think of opening the windows, but you can judge by the RPM and battery meter).

http://www.youtube.com/watch?feature...&v=OiozMkuHPlA


When the engine is cold, RPM will go up and down to start (which I think is normal, but I can't say that I noticed it before), and then it steadies for about 30 seconds to 1 minute (but even then the rpm wobbles between 700-900). And then it starts to idle really rough, car is shaking at that point, almost stalling, but it revs back up just in time to avoid the stall.

If I rev up the engine passed 2000 RPM it seems to run just fine, or maybe it's just hiding the problem at that point? I'm really at a lost as to what could be going on.

I triple verified the spark plug wires and firing order on the cap and they are fine.

Here's the parts I put in the car :

52913 - Ford Motorcraft OEM Spark Plugs (87-95 5.0L)
14212 - MSD Super Conductor 8.5mm Spark Plug Wires - Red (79-93 5.0L)
14230 - MSD Replacement Cap & Rotor (86-95 5.0L)
14205 - MSD TFI Performance Coil (86-95 5.0L)

Any help is appreciated. Thank you!!
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Old 05-13-2012, 10:07 AM
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senatorsfc
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So I just tried pulling some spark plug wires off while the engine was running, and could barely see a difference (I even tried with 2 pulled out).

I runs just as bad (nearly stalling) with the spark plug wires back in compared to having 1 or 2 pulled out.

Really scratching my head...
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Old 05-14-2012, 09:31 AM
  #3  
Tony71502
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Check timing. Also, just because the CEL is not on does not mean you don't have codes. KOEO and KOER tests.
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Old 05-05-2013, 09:12 PM
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marlyman
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http://www.stangnet.com/mustang-foru...stangs.787471/


http://www.muscularmustangs.com/idlereset.php

http://sbftech.com/index.php/topic,1031


http://www.veryuseful.com/


All the links u'll ever need ; ) this site is #1 help tho...

Honestly sounds like u are having some surging issues with ur idle...do a base idle reset (properly) an u should be good...
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Old 05-06-2013, 07:45 AM
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senatorsfc
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I figured it out not too long after. When doing the tuneup, I moved the distributor a bit when changing the distributor cap, which messed up the timing.
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Old 05-06-2013, 06:07 PM
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89StangGTConvertible
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Originally Posted by senatorsfc
I figured it out not too long after. When doing the tuneup, I moved the distributor a bit when changing the distributor cap, which messed up the timing.
Yep - a small turn of the dizzy will do that every time! Follow links above that marlyman posted to reset your idle, too. Make sure your TPS is in range. You'd be surprised how nice your car will idle afterwards. My car had severe "rolling idle"... now it holds steady at about 850 rpms at idle.
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