P0172 code 2001 focus

I have a 2001 ford focus 2.0 dohc with 170,000 miles on it. Car drives fine but idle is rough. It is giving me a p0172 code running rich. Car has a long cold crank time but starts fine when warm. Now when I start the car from a cold start the rpm reach 3k before settling down at normal idle. Please help

That is n system too rich code. What troubleshooting have you done.

You really need to start by looking at live data from the system, all the data pids that are connected with the fueling.
You need to investigate if you have a true rich condition or a false rich condition. The data pids you need are.
STFT
LTF
B1S1
B1S2
I would also check the MAP and MAF live data and the CTS.
Also is the airfilter and its' pipework completely stock ? -- not K&N or similar ? and reasonably clean?
After that I would check fuel pressure.
The spark plugs are resonably easy to access on these engines so check the spark plugs are all the same colour, if one plug is sooty it points to a stuck open injector.

I replaced the iac motor and the high rpm was the result. Warm idle is about the same as it was before I replaced the iac. I have a scan tool and the numbers are as follows;
Calc load - 40.8
Ect. -179.6
Stft. - -7.8
Ltft. - -25.0
Fuel pres - 39.2
Rpm. -710
Iat. -42.8
Maf.lb/min - 0.4
Tps. - 14.1
02s b1s1 -0.500
02s b1s2 -0.765
Stft b1s1 - -1.6
Stft b1s2 - 99.2
Thanks for the replies I appreciate it.
Lastly the issues with this car started after the battery went bad and the corrosion got into the ground wire itself. Then the hard starting. Replaced battery and ground to block wire still having the issues. Sometimes car will not idle and dies. (Rarely)

Air box is stock.
Clean filter
I will check spark plugs again they were fine when I changed them the old ones looked good.

B1S1 0.500v ---- that looks like the PCM is using a substituted value for the pre-cat O2 B1S1 sensor.
The pre-cat O2 sensor is a good place to start the investigation. As the problem started after a block ground cable failure I would start by checking the sensor heater power, heater ground and sensor ground.
From a cold start the sensor output voltage on both B1S1 and B1S2 should initially flatline low then as the engine warms up first B1S1 then B1S2 should come to life.

Thank you for the reply and the video. I will check that sensor asap. I am also ordering a ford oem iac valve from the dealership the one I installed was autozone. Cheaper isn't better I have read about issues with high idle from bad iac valves. I guess if the valve isn't opening all the way it can restrict airflow causing a rich condition and or high idle. I have cleaned the maf sensor and the connectors with no change but I will back probe the maf to ensure it has good power and ground. I will also review those o2 sensor numbers from cold start to warm and post those numbers and the results from my other tests including sensor heater power, heater ground, and sensor ground. Thanks again for helping out.

Regarding O2 sensor 1 reading .5v, is there any appreciable change in the v if you do a snap throttle or introduce vacuum leak?
This would test sensor and circuit operation.

I suspect the sensor isn't actually reading 0.5v from B1S1 but the PCM is not reading the sensor but substituting a default value.

On Hot Idle B1S1 and B2S2 when running closed loop should look like this. B1S1 is continuously switching hi-lo-hi-lo adjusting the fueling around the ideal air-fuel ratio. When the fueling is correct and the cat is working properly B1S2 should always show a high voltage at idle as all the O2 in the exhaust is used by the catalysts.




Then snap throttle B1S1 and B1S2 both go rich then dip lean then B1S1 should quickly recover back to normal closed loop hi-lo-hi-lo.
B1S2 recovers more slowly.

The obd2 scanner I am using fluctuates pretty fast. On the o2s b1s1 ranges from 0.025- 0.815 on first test and 0.025- 0.500 second test which is why I wrote down the last number. I will check these while I do snap throttle response test and vacuum leak test. Thanks for the help I will repost results tomorrow.

The fluctuating B1S1 voltage suggests that you have a a true rich condition that is being trimmed out. What conditions was the car operating under when the live data was taken ? as 40% calculated load at 710rpm seems too high. The airflow reported by the MAF which my maths {edit now corrected ! } converts to roughly 3.0 grams/second seems too OK for a 2 litre gasoline engine at 750 rpm idle. The problem is I don't know the normal MAF reading for this engine and I would also suggest checking the sensor powers and grounds first especially as the car had a block ground problem which may have overloaded other ground circuits.
What you could try is clearing the codes then disconnecting the battery for ten to twenty minutes and watch what happens to the fuel trims when you restart the engine and allow it to fully reach running temperature.

Update on the fuel trim numbers. I wrote down the numbers on startup at 2800 rpm, while warm, and while doing snap throttle test.
For some reason my LTFT b1 stayed at 0.0 throughout each reading cold, warm, and snap throttle. STFT b1 was -18.8 cold start (2800rpm), 0.0 warm, and -20.0 snap throttle.
O2s b1s1 was 0.850/0.870/0.915
O2s b1s2 was 0.690/0.970/0.975
Tps was 14.1 all three.
Maf was 0.5/0.4/2.4 (lb/min)
These numbers are very confusing for me but someone can make more sense of it than me. My assumption is that the LTFT isn't responding with the pcm to adjust the fuel. Maybe the pcm is fried from bad grounding and isn't working properly. I'm lost. Also the check engine light is gone w/o erasing the code. Did disconnect battery all rough running ,stalling, high rpm is same.

I will add that I swapped the iac for another thinking it was defective but no change. Dealership wants $220 compared to $80 (zone) for a new one so I used the autozone part. I disconnected the battery and then did the last 3 tests mentioned above.

When I took the first reading at 40% load 710 rpm was after the idle settled down from close to 3k rpm. Car was warming up.

Maybe Mr Danner can weigh in on this one.
It's not clear to me if the O2sensor is switching or you are posting the highest readings.
With scanner set to read only live O2 sensor voltage is it moving low/high high low every second or so?

The focus of interest is when the engine is properly hot and the pre-cat O2 sensor B1S1 is responding and the engine is running closed loop.
B1S2 is really only to confirm the catlyst is actually doing its job.
On 99% of vehicles B1S2 plays no part in the control of the fueling of the engine.
The fuel trims are a measure of how much the the PCM has to deviate from the basic fueling map stored in the PCM to bring the output from B1S1 back to continuously "switching" hi-lo-hi-lo from roughly 0.1 volts to 0.8 volts.

Short term fuel trim STF1 is exactly what it implies a short term rapid correction, long term fuel trim LTF1 is a longer term correction based the average of short term trim.
An engine in perfect condition will normally have the fuel trims close to zero for example STF1 3% LTF -2%.
Generally a total fuel trim STF1 + LTF of less than10% is generally considered well within normal bounds.

Provided the pre-cat Oxygen sensor is responding what is very useful for diagnostics are the changes in STF and LTF at different RPMs as these can be a good clue for revealing vacuum leaks or a dirty MAF.
An engine with a MAF that is running lean at idle (STF and LTF adding fuel) but rich (STF taking fuel away) when RPM is increased suggests a vacuum leak.
If the LTF is adding fuel at idle and the STF adds even more fuel as RPM increases then suspect a dirty or unserviceable MAF.

Last night I drove around my neighborhood with my scanner hooked up. I noticed that my o2s1 stayed very consistent with o2s2
o2s1 - from 0.840 up to .930
o2s2 - from 0.845 up to .970
Then the rpm would get stuck at 1790rpm without my foot on the accelerator. I had to use the brake pedal to slow down and the car would pull itself. Once the car came to a stop the rpm would decrease to normal after a hard jerking motion. It did not want to idle down as if the accelerator cable were stuck. I have checked this cable and it operates normally with no sticking.
When the engine gets stuck in high rpm normally after acceleration STFT was 2.3 then -2.3 going up and down.
LTFT stayed at -3.1
Maf 2.0
Tps 14.5 then I saw very briefly 16.5 then back to 14.5.
o2s1 fluctuating from 7.20 to .090
o2s2 fluctuating from .690 to .720.
Once the engine would kick at a stop and finally idle down the numbers were
STFT -20
LTFT 0.0
O2s1 fluctuating from .920 to 0.015
o2s2 stayed close to .950
Maf 0.4
Tps 14.5
At a stop sign normal rpm was 650rpm and STFT B1 NEGATIVE 20
STFT B2 NEGATIVE 25
Does this seem more of a sensor issue or maybe a issue with the pcm?

Work that erratic engine speed. Intermittently getting stuck in higher rpm after letting off accelerator could be IAC/TPS circuits /PCM or throttle mechanically not closing properly due to binding or being held.

If there are no other codes that would point to IAC/TPS being out of spec try to reproduce the problem with car parked engine running.
Set scanner to read only RPM/IAC and TPS, while pushing/releasing accelerator many times over, look for readings that increase/decrease consistently.

Regarding a mechanical problem, when the RPM sticks high, try quick tap on accelerator to see if it will cause rpm to come down.

Finally you mention replacing the IAC and the high idle was the result. Did you mean that this problem began after the install.
If so try to reinstall original.

Today I started the car. It idled up to 2500 rpm and then settled down to normal rpm. Much better but the check engin light came on.
P0113 Intake air temp sensor which is integrated into the maf sensor. Sensor signal circuit is open or shorted to vref (5v). Iat is damaged or failed. Iat sensor 1 circuit high input.
Pcm has failed.
That is what my scanner said. I will add that I had unplugged the maf sensor while idling last night to check for a change in idle with no change. Then plugged it back in so maybe the code if from unplugging it and the code din come on untill a day later? I will clear the code and see if it comes back but maybe this is the culprit. Also the old iac valve was sticking upon visual inspection and the car wouldn't start at all sometimes with the old iac.

Yes unplugging IAT should set the P0113.
When engine is stone cold compare the ECT/IAT, should read about the same.

Looks like you'll have to keep trying to reproduce that stuck high idle. When it happens try tapping the accelerator pedal to see if it kicks down.
Meantime try to establish that IAC/TPS readings stay consistent thru out the RPM range.