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I posted a month or two ago with the problem of very rough idle, only when very cold (below 30 degrees). At that time I had both PO174 and PO171 codes. I was thinking a vacuum leak, but sprayed around and could not find one. I decided to replace the TSS because in the summer I felt I should have. After replacing the TSS the problem seemed to go away. Of course since then it has not been extreamly cold. Until this week. Monday the rough idle came back. It only idles rough in park. If I keep reving the engine long enough the car will not die, but will end up idling very low around 500 or so. Once out of Park and in gear it idles fine. Yesterday I finally got a CEL and it came up with only one lean code PO174. Do you still think this is a vacuum leak? Even though I sprayed carb cleaner around on the vacuum lines and connections and found nothing? If so I guess I will take it to the shop and hope they can find it instead.
Thanks for any info and sorry to bother you with this problem.
98 Black Mystique LS Duratec V6 2.5L ATX
K&N air filter, cleaned EGR, new Autolite double platinum plugs, magnacore wires, rebuit Sonnax valved VB, TSS, TPS.
Mobil 1 5W-30
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Addicted CEG\'er
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Check loose hose clamps for rubber hoses and check for broken or cracked hose lines too. Do you, by any chance, have a leaky exhaust in the front?
From TSB.
P0174 - System Too Lean (Bank 2-Radiator side)
The Adaptive Fuel Strategy continuously monitors fuel delivery hardware. The code is set when the adaptive fuel tables reach a rich calibrated limit.
Fuel System:
�· Contaminated fuel injectors
�· Low fuel pressure or running out of fuel (fuel pump, filter, fuel supply line restrictions)
�· Vapor recovery system (VMV)
Induction System:
�· MAF contamination
�· Air leaks between the MAF and throttle body
�· Vacuum leaks
�· PCV system concern
�· Improperly seated engine oil dipstick
EGR System:
�· Leaking gasket
�· Stuck EGR valve
�· Leaking diaphragm or EVR
Base Engine:
�· Exhaust leaks before or near the HO2S
�· Secondary air concern
Powertrain Control System:
�· PCM concern
"Always do the cheap and easy ones first."
1996 V6 ATX 96K miles
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Originally posted by Tony2005:
Check loose hose clamps for rubber hoses and check for broken or cracked hose lines too. Do you, by any chance, have a leaky exhaust in the front?
No exhaust leak that I know of, but how could I check that?
98 Black Mystique LS Duratec V6 2.5L ATX
K&N air filter, cleaned EGR, new Autolite double platinum plugs, magnacore wires, rebuit Sonnax valved VB, TSS, TPS.
Mobil 1 5W-30
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Joined: Jun 2005
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You should be able to hear a slight ticking or hissing if you have one.
"Always do the cheap and easy ones first."
1996 V6 ATX 96K miles
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Then no. I do not have an exhaust leak. I do not hear ticking or hissing.
98 Black Mystique LS Duratec V6 2.5L ATX
K&N air filter, cleaned EGR, new Autolite double platinum plugs, magnacore wires, rebuit Sonnax valved VB, TSS, TPS.
Mobil 1 5W-30
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Originally posted by Ra\/en:
Then no. I do not have an exhaust leak. I do not hear ticking or hissing.
You have a vacuum leak that is aggravated when the extreme temps cause everything to shrink.
See if your shop has a smoke tester. They can make finding a leak much quicker.
Common leaks are the intake gaskets, the PVC valve hose, and around the IAC. There's a real mess of plumbing to be looked at.
Steve
98 Contour SE Sport 2.5 Duratec ATX The wifey's car
89 Taurus SHO - 246K miles
94 SHO ATX - 190K
1997 F-150 5.4L ATX - The Workhorse 150K.
ANY THREAD WITH "OMG" or "WTF" ETC IN THE TITLE WILL BE IGNORED!
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My rough idle finally went away when I replaced the TPS. The vacuum leaks made the car sluggish and run stupid at speed. The intermittant TPS bug caused a jumpy idle, hesitation when cold and lean outs on brisk acceleration.
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I just replaced the TPS not long ago, didn't help. I guess I will just take it to the shop.
Thanks.
Last edited by Ra\/en; 02/10/06 03:33 PM.
98 Black Mystique LS Duratec V6 2.5L ATX
K&N air filter, cleaned EGR, new Autolite double platinum plugs, magnacore wires, rebuit Sonnax valved VB, TSS, TPS.
Mobil 1 5W-30
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Joined: Oct 2000
Posts: 770
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Last time I had a lean code on only one O2 sensor the sensor was not switching like it should. I tossed both out because I figured one will follow the other. The lean code went away. Only way to find out is to run a real time scan and monitor the sensors. If the sensors are the originals it probably is time to 86 them. 
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I'm struggling with same thing as we speak!
I'm going to look again for a vacuum leak later. Don't want to take it to a dealer but I'm running out of options. I took it to the tech I usually go to. He cleaned all the sensors,checked for leaks, cleaned the TB etc...
He also put a set of Champion platinum plugs in my Zetec. I'm wondering about that as well.
95 Contour GL. Bought new.
BAT Sway Bars/Pioneer CD/Koni Rear Struts/Mobil Fluids.
Looking for 15" alloy rims-PM me.
180,500km's so far.
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