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Discussion Starter · #1 · (Edited)
Hello,

I have 2004 Ford Taurus with high idle issue. I did a live data scan with my OBD2 tool and the RPMs during cold start is approx. 1450 and when driving or at operating temp, it stays around 925. Also, when the AC/heat is on, the RPM drops to around 750 to 800.

There are no check engine light/codes. I sprayed brake cleaner around all the hoses/vacuum lines and it didn't make any difference. I swapped the throttle body & MAF sensors and it didn't resolve the issue. Also, the fuel pressure fluctuates between 39.5 to 41.5, so could it be a bad fuel pressure sensor, faulty fuel injector(s) or the manifold runner control o-ring?

Thanks in advance.
 

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Try cleaning out the IAC with some throttle body cleaner, it may have some carbon preventing it from returning to its default stop. Same with the throttle blade, take the intake off and clean both.
 

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Discussion Starter · #5 ·
Forgot to mention earlier, the valve cover gaskets and intake manifold gaskets were also replaced due to oil leaks. When it was replaced, the IAC, throttle body, IRMC were all cleaned but didn't make any difference in the idle.

Wondering if I should replace the fuel filter and fuel pressure sensor or do a smoke test for any hidden vacuum leak.
 

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Hello,

I have 2004 Ford Taurus with high idle issue. I did a live data scan with my OBD2 tool and the RPMs during cold start is approx. 1450 and when driving or at operating temp, it stays around 925. Also, when the AC/heat is on, the RPM drops to around 750 to 800.

There are no check engine light/codes. I sprayed brake cleaner around all the hoses/vacuum lines and it didn't make any difference. I swapped the throttle body & MAF sensors and it didn't resolve the issue. Also, the fuel pressure fluctuates between 39.5 to 41.5, so could it be a bad fuel pressure sensor, faulty fuel injector(s) or the manifold runner control o-ring?

Thanks in advance.
Very normal fuel pressure. Check fuel trims. I had '04 leaking around the EGR gasket but not enough to set a code. ~=15-20% at warm idle. Made for high idle and less than happy when cold.
Wrong gasket on the EGR to intake. Small leak.
-chart-
 

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Thanks. I will check the EGR gasket area and the o-ring going into the intake.
It leaks or not, best check fuel trims at warm idle and let it tell you if you have an issue. Pic of mine after fix.
Any thing +/-10% not an issue. Best not trying to fix things not broken. I had bad data, traced it to this, first time in all my 11 Bulls had this. Lots of things can cause vacuum leaks, but first test to see if you have an leak. If not move on, it it is leaking, then find out where.
-chart-
 

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Discussion Starter · #10 ·
Results during cold start. The first two pics are blurry...sorry about this.

.
Gadget Font Gas Electric blue Multimedia
Gadget Font Gas Electric blue Multimedia




At Operating temperature and idling. The second pic, I noticed the STFT B1 % dropped to 0 few times.

Azure Font Rectangle Gas Electric blue
Azure Font Gas Electric blue Rectangle



Screenshots of the O2 sensor readings

Font Gas Electric blue Commemorative plaque Rectangle

Font Gas Electric blue Technology Commemorative plaque



Fuel Pressure Reading

Blue Font Gas Electric blue Electronic device
 

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With the engine running at temp, unplug the IAC and the idle should drop to a just barely running 450-500 rpm. If not, someone may have opened the bleed air adjustment or throttle stop to raise the idle, and your cleaning everything may have fixed the original issue..

Another possibility is a sticking evap purge valve, it can be cleaned in the same manner as the IAC
 

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Discussion Starter · #13 ·
With the engine running at temp, unplug the IAC and the idle should drop to a just barely running 450-500 rpm. If not, someone may have opened the bleed air adjustment or throttle stop to raise the idle, and your cleaning everything may have fixed the original issue..

Another possibility is a sticking evap purge valve, it can be cleaned in the same manner as the IAC
The idle drops when the IAC is unplugged, but didn't check the RPM.

Where is the bleed air adjustment or throttle stop? Also, I will try cleaning the evap purge valve.
 

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Okay, thanks.
Just for discussion. Engine rpm/power is managed by air flow. Throttle manages air flow, and IAC manages air flow, and PCV manages air flow. Then leaks add air.
The PCM adds fuel to math that air as measured by the MAF. If idle is too high and trims are in line, then one of the managed air flows is high. The PCM is making it high.
I know from experience, it you open up the throttle plate screw idle stop, it will not make the idle go up. PCM just adjusts for that. Things that make the PCM add more idle. PS pressure switch, and A/C clutch relay. Both to correct added load. If the A/C clutch it called for and it does not engage or no load is experienced when it does, idle jumps up and is not matched by load.
From experience: PCV stuck closed/ or wrong size for the car and idle will be low or high and the PCM will not try to correct. Had cheap Autozone PCV and car would drive 30 mph on level ground.
-chart-
 

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Discussion Starter · #19 ·
Thanks. So, if I have it on Drive, it would easily drive up to 20 miles on level ground and I don't need to put my foot on the pedal.

I didn't see any leaks by the PCV elbow or line, but will clean or swap the PCV if required.
 
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