Bad Idle & Misfire: Help appreciated - TCCoA Forums
 
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post #1 of 4 (permalink) Old 06-10-2012, 11:09 PM Thread Starter
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Bad Idle & Misfire: Help appreciated

Okay, its a '93 T-bird with the 3.8 V6. As my title implies, it has a rough idle/shake to it especially at lower rpms. It has never been a smooth car, but it has gotten worse over time.

What I replaced:

-Plugs & wires
-IAC Valve
-PCV valve
-Vacuum lines
- Distributor cap & Rotor
- Fuel Filter
- Fuel Pressure Regulator
-MAF sensor clean

That's all the relevant parts that come to mind right now.

Other Information:

- Run 93 Octane
- Change oil regularly
- No CEL
- Got a code 558 (KOEO) for "EGR Vacuum Circuit Failure"
- Has been dying at idle sometimes, but can this EGR issue really be messing it up like this? I have replaced so much, and it hasn't responded too much to my work. I have yet to find someone who can figure this out, unfortunately. So, does anyone have/know of this? I have no problem fixing this, but id rather not if it doesnt help like everything else. Any and all thoughts appreciated

Thanks

Jonathan

1993 Thunderbird LX. 3.8L with Underdrive Pulleys, Ford Racing Limited-Slip Differential, Intake & Dual Exhaust, and I like to run advanced timing
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post #2 of 4 (permalink) Old 06-10-2012, 11:59 PM
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Well I know if the EGR valve gets stuck open it will cause an " internal " vacuum leak and the engine will act the way you are describing . It happened to my wifes Saturn so i pulled it and cleaned with carb cleaner while moving the valve with a small screwdriver and it ran just fine.
You could always make a temperary block off plate just to see if it smoothes out.

Jason H.
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post #3 of 4 (permalink) Old 06-11-2012, 05:52 AM
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I did some poking around, could be pointing to a couple of things.

Check the EGR Vacuum Regulator (EVR) then look at the DPFE (Pressure Feedback Sensor).

Joe

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post #4 of 4 (permalink) Old 06-11-2012, 08:41 AM
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Oh yea forgot about those they go out quite a lot that little white doo hicky on the top of the egr valve

Jason H.
Mods:
Exterior- Paint, grill, trim, SHO wheels
Power train- 4.6 cat back w/ muffler delete 2"I.D. tips , Taylor Pro Series plug wires, intake silencer delete

Photographs http://s1175.photobucket.com/user/jh...?sort=4&page=1
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