P0172 code 2001 focus

Car is now warm
ECT 168.8
RPM 724
IAT 46.4
TPS 14.1
NEGATIVE fuel trim numbers.
The IAT was at 44.6 at start up
With ECT at 185
IAT Is at 51.8
@700 rpm

While warm
O2s b1s1 stays at .780-.790
O2s b1s2 stays at .950-.955
Finally figured out how to pull up the graph mode on this code reader. I can post a picture if needed.

O2b1s1 sensor v sometimes moves normally at idle but most times reads high .8v correct?
When it is stuck high create a vacuum leak to see if sensor reacts and v goes toward 0v.
If so then assume sensor good and suspect maf is over reporting or excess fuel is being delivered.

Maf is easiest to check at idle should run around 2 g/sec and increase to around 70g/sec 80% load.
The past maf reading at idle look to be around 4 g/s however higher idle of a few hundred RPMs may account for this.

Can you do a fuel pressure/fuel leak down test?
Trying to determine if there is an injector leaking fuel.
At one point you mentioned long crank time so maybe there is an over fueling problem.

Yes. O2s1 b1 at idle slowly increases as engine temp goes up. Then warm will read high .8v steady. When the rpm gets stuck around 1700 rpm the sensor moves hi-lo-hi-low and will read low less than .1v for the majority of the high idle condition untill the idle comes down. Once idle comes back down the numbers go back to around .8v. This high idle condition is not present while in park or neutral. I will try the vacuum leak test to check for sensor operation.
Regarding fuel pressure, the numbers stay at about 40 psi with no big fluctuations. I will try to remove the fuel rail and injectors and put them into clear water bottles so I can check to see if they leak after I stop cranking over the engine. Are there any other tests I can do to check for leaking injectors.? I already made sure they are within spec of electrical resistance.

Fuel pressure normal with engine running, shut off engine fuel pressure stays normal.
If so then leak down test good,injector not leaking.

O2 sensor b1s1 reads high at idle( fuel trim negative) and at higher RPM O2 reads low(fuel trim goes towards zero)
If maf is over reporting at idle and under reporting at higher RPM then suspect maf.

Set scan tool to read maf/stft/rpm only. Should read around .26 lb/min at 650 RPM and gradually increase up to 2.6 lb/min at 2000 RPM,
6 lb/min at 3500.
If the maf readings aren't in the ball park trying cleaning and retesting.
maf and sensor are original, can't recall?

Yes all sensors are original.
Today I did the fuel pressure test. Normal operating temp the fuel pressure is 40 psi.
When I shUT off the engine it goes down to 10 psi and slowly drops. This happens in the first couple Secones of shutting car off. Also the IAT got up to 109.4 and after I shut the car off it went up to 141 with ECT of 179 degrees.
I did the test to check the maf at different rpm. At idle it was 0.4 at 1200rpm it was 1.1 and at 3500 plus rpm maf reads 2.5. This must be too low. Now the car will not start I'm guessing it's flooded from restarting 3 or 4 times. No check engine light. It's getting spark and I used starting fluid but still no start at all.

Try holding accelerator pedal to floor before/during cranking to clear any excess fuel.
IAT/maf look ballpark.

Check for leaking injectors or check valve/fuel pump causing loss of pressure engine off.
You mentioned removing fuel rail checking for leaking injector.
Not familiar with Focus, can you block of fuel line to see if pressure lost to injectors or check valve/pump

I held the accelerator all the way down with no success. Also, the fuel pump was replaced so I believe the problem to be the injectors. Hopefully so I can get this thing going again. I will try to start it again today, if it starts then it was flooded. Thanks for helping me along it really helps when your not alone. I'm going to do the leak down test with water botties to pinpoint which injectors leak. I hope this is the problem so I can sleep at night.

I'm curious if you have down a compression test and a leak down test? i thought i posted this last weekend on this one but I'm not seeing it, so here it goes I've lived through a couple of these 2.0 focus rich condition and sometimes follows with a MAF code but not all the time. The symptoms you've reported with the fault code I'm suspecting a valve seat failure, I cant tell you how many of these I've seen with this common failure and with your mileage I'm suspecting it even more. I believe this is a mechanical failure and your dealing with it at its early symptoms eventually that valve seat is gonna break and scatter in the combustion chamber were it will get sucked back into the intake and end up in the other cylinders. This is very common on these engines, rough idle with no real drive complaint "at first", followed by the rich code and as I said as well as a MAF code. In the several I've dealt with usually #3 cyl but I've seen all four affected in one case or another. I've learned to deal with these as they are all the same before scoping any sensors to cut my time down and this has paid off several times, Now I just do a relative compression test and pull the plugs and stab my bore scope and look at the valves "more commonly intake valves are the culprit". ok so i guess that should do for now Ill be following this one waiting to hear the fix. Compression test then leak down. Good luck.

I'm not sure how accurate my compression tester is since I dropped it on the concrete garage floor but here are the readings.
Cyl 1 - 185
Cyl 2 - 150
Cyl 3 - 165
Cyl 4 - 155
I did a leak down test on Cyl 2 and 4 with no change. I guess this might confirm your theory. Also, how difficult was this to fix?
Did you replace the valves and valve seats?

I pulled the spark plugs and cylinder 2 and 3 were soaked in fuel. The other two were dry but a little burnt/blackish. I'm running on two cylinders when I try to start it it barely runs with accelerator floored (flooded cyl).

Even with the new dry plugs I put in.

yes it takes the head to be pulled and sent out and have new valves and seats installed and if caught in time before the piston and jugs get damaged it will be pro "good to go". I'm also curious of the running compression, this is done one cylinder at a time of course you need to pull the release valve from the tester. also one question I have when you did the compression test you are holding the throttle wide open so each cylinder is getting the same volume of air going into the cylinder? I say this only because it can and will be a false reading it can very 10psi +/- if the throttle body is closed. Do you have a bore scope available to you? they make a fairly good affordable one that connects to a smart phone if this is a piece of equipment that could be used in your arsenal. its looking like you maybe pulling the head

those injectors are pretty easy to swap. do a 2/1 and 4/3 swap and you can then rule out the injectors if the misfire moves with the injectors then let me know I have a used set. this will also may explain the compression reading you got if the rings are being washed out by fuel. but Im still leaning towards the valve seat issue. good luck friend let me know.

I haven't done a "running compression test" before but the test I did I held the accel down and for the same amount of cranks. I will check the injectors first and I will look at some bore scopes. What am I looking for with a bore scope? A burnt valve or just peices of metal in the cylinder? Btw thanks for helping out I feel much closer to finding the real problem.

Agree with above swap injectors over, here in the UK the 1.6, 1.8 and 2.0 fords are common for injectors causing a P0172 can be a pain to diagnose as they normally don't act up whilst testing :huh:

Alternatively if you have or know of anyone with an ASNU bench get them out and tested

Carl

over here (uk) we have problems with pcv valves and pipes going hard and splitting and collapsing i have replaced a lot of them ,
smoke it to see ?

Very true but that normally gives you a lean condition

the shrader valve "same thing as a tire valve" at the end of the compression gauge whip were it threads into the spark plug hole, you need to pull that out and then one cylinder at a time run the engine, the gauge will bounce but you will be able to see the average pressure. this is a running compression test. after swapping those injectors over try to do this test to get the result. as I said before im pretty sure the head is going to have to come off. let us know, good luck.

I was able to pull the fuel rail with injectors attached and watch for the fuel pressure to leak out. No leak at injectors but did notice a strong raw fuel smell. After some fiddling I pulled the vacuum hose that goes from the fuel pressure sensor to back of intake. With the side that connect to the intake unplugged I was able to capture the fuel comming out of that hose. Every time I pressurized the system fuel was dumping straight into the intake via this vacuum hose. I have read that the fuel pressure sensor has a diaphragm in side that can fail and leak fuel. Does anyone have any experience with these sensors? Should I swap this $130 part even with no cel on?