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Discussion Starter · #1 ·
Greetings my fellow Taurus owners!!!

I just bought a 1997 with the 3.0 OHV Engine (U)
Car has 109k and runs very strong.. Love it!!!

Here's the problem:
NO DTC's present, stored or pending. When the engine is idling in park or drive there is a very distinct "miss". There is no pattern to it and you can even see the engine move slightly with the "miss". If I give it some throttle it goes away or at least gets better. NOW, the most annoying part is that it will "buck" or seem to "miss" when just driving at a steady speed with light throttle involved. Increase the throttle and it again goes away. This gets very annoying while driving in cruise!!
This happens with A/C on or off, warm or cold engine.
Like I said the car has 109k miles so the first thing I did was a tune up and replaced:
Plugs (Motorcraft)
Wires (Motorcraft)
Coil (Motorcraft)
Fuel Filter (Motorcraft)
Cleaned Idle Air Control valve, cleaned throttle body, cleaned intake manifold with SeaFoam, D/C fuel pump relay and ran cleaner through injectors, and cleaned MAF meter with uhm.. MAF cleaner...
The problem is still there.

Fuel pressure is normal and gas mileage is excellent.
I have searched and read countless threads where the problem was resolved by one of the above stated repairs and with all of that being replaced I decided to open my own help thread.

Thanks to anyone who can help!!
 

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I had a similar problem with my '03 Taurus (Vulcan OHV engine). Turns out it was the part shown below. The hole wasn't as bad as it seems in the picture; I stuck the ink pen through the hole to emphasize the problem. This part is called the "Crankcase Vent Hose and Connector" and is Motorcraft p/n 6C324. The assembly includes the PCV valve, but you can buy just the elbow where the hole is seen for a couple dollars less. You might check to see if your '97 has this (or a similar) device. On the '03 Vulcan engine it can be found connecting the passenger side of the intake manifold to the valve cover. The PCV valve inserts into the valve cover on the firewall side of the engine. Once I replaced this part, the tachometer sits absolutely still at idle. Perfect!

I used this site to get the part number and then bought the part at the dealership. You might be able to find the elbow (where the ink pen is jammed through) at your favorite parts store (?).
http://www.fordparts.com/Landing/Motorcraft.aspx

PCV01.JPG
 

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Discussion Starter · #3 ·
PCV valve is in fact on my list of "need to replace" parts. However I had no Idea that it would cause an idle issue sice I already checked the hose.
BTW mine is different on the 97 Vulcan.
Gonna grab one tomorrow along with a hose.
Crankcase Ventilation Hose
 

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Discussion Starter · #4 ·
Just spent over an hour checking every vacuum line and hose. No leaks.
Replaced PCV valve and reset the PCM. Problem is still there.
I suppose at this point I will run a full on diagnostic and monitor the A/F, spark, timing, injector cycle etc.. to see what abnormalities are there.

I am sure after all this it will be something simple...:rolleyes2:
 

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Discussion Starter · #5 · (Edited)
Data logging results.

Scanned and monitored PID's with the Ford VCM using the IDS software.

Operating temp, in Park, A/C off, Hot idle, and key on engine off.

PID's Monitored:

Intake air temp sensor
DPFEGR
Mass air flow meter volts
TPS volts
All 4 o2 sensors
Long fuel trim1
Long fuel trim2
Short fuel trim1
Short fuel trim2
Idle air contol valve
Vehicle power voltage

ALL the above where within the diagnostic reference values.
The ONLY strange thing was with the long term and short term fuel trim.
LONGFT1 and LONGFT2 were within the (-)20-(+)20 range but bank 1 would stay richer than bank 2.
LONGFT1= 1.07 / -0.73
LONGFT2= 4.33 / 1.10

***(Edited) - MAF volts were at a steady 1.17 although the Values say .6-.9. Not too much higher but weather and other factors affect this i believe.
Also ran the TPS sweep test and at WOT the blue bar that increases as you increase throttle stopped 3/4 of the way up even though I was at WOT.
Ran another TPS volt test, with key on engine off and max reading WOT was 4.52
Any Ideas or comments would be appreciated!

Going to try to run another data log while driving tomorrow.
 
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