2000 Taurus dies at idle after warmed up

[routerman]

I'll give you everything I have..It looks like it only collected for the P0174 error...Actually I think you may need these live which I'll have to do when the cars back and figure out how to do that as well on the tool....

Fuel Sys 1 CL
Calc LOAD 22.7
ECT 188
STFT B1 16.4
LTFT B1 25.0
STFT B2 18.7
LTFT B2 25.0
Fuel Pressure 110.9
RPM 1377
Veh Speed 34

[Breeves002]

So it looks like it is running lean on both banks. See how the LTFT is 25% on both banks? That means you should be getting both P0171&P0174 codes.

It is PROBABLY a vacuum leak. That is most common with these codes. I would be checking the PCV elbow to the left of and behind the throttle body that connects on the bottom side of the upper intake. (when I say left I mean left as you are looking from the front of the car at the motor).

Just look it up. $10 for the elbow at your local parts store. Can get whole hose and elbow from rock auto. Make sure it is actually the problem first. Could do a smoke test (blow cigar smoke into a vacuum tube with engine off) to find leaks.

[routerman]

Ok, I'll have to look when she gets home with it or tomorrow if it's too late. I did replace the elbow on the line on the PCV that connected to the air intake line before the TB as it was broken. What should those values be btw? 25% is what I have but what should it be?

[sheila]

Po171/174 lean codes almost always indicate vacuum leak(s). Po172/175 are rich codes.

[behlinla]

If all those fuel trim numbers are indeed positive, it means you're in the neighborhood of +40% or more with the total fuel trims. This means the engine is having to add 40% more fuel to compensate for the leak. Since the number is so high, it means you must have a massive vacuum leak somewhere. If it happened after you replaced the PCV, I would retrace you steps carefully. You might have forgotten to connect or tighten something, or something fell off.

When the engine is operating perfectly, the fuel trims will be 0%. But normal variation is ±5%.

Can you specify what units the fuel pressure is in? If the units are kPa, then you only have 16 psi of fuel pressure (which is very low), which might also cause your P0171/P0174 codes.

So check for loose hoses and also check the fuel pressure with an external gauge to confirm the reading.

[Breeves002]

That motor would be stumbling and nearly dying if it is at 16psi at idle. That would cause those codes in a heartbeat.

I agree 100% with behlinla on this one.

[routerman]

The information I supplied bofore was what was stored in the tool when the P0174 error occurred and wasn't at idle. I checked PCV lines and they are both connected and not leaking. That was what I originally suspected the problem was and replaced the elbow but issue still exists. Here's the data from the OBD tool live at idle. I looked over the lines I could get to and don't see or feel any leaks. I collected more frames than the one listed below and can provide more if neded. I assume these numbers all mean something to you guys and I really appreciate you taking the time to look.

Fuel Sys 1 OL-Fault
Calc LOAD 23.5
ECT 197
STFT B1 0
LTFT B1 0
STFT B2 0
LTFT B2 0
Fuel Pressure(Psi) 38.2
RPM 492
Veh Speed 0
Spark Adv 16
IAT 59
MAF 0.775
TPS 16.4
O2S B1 S1(V) 0.010
STFT B1 S1(%) 0
O2S B1 S2(V) 0.010
STFT B1 S2(%) NA
O2S B2 S1(V) 0.010
STFT B2 S1(%) 0
O2S B2 S2(V) 0.010
STFT B2 S2(%) NA

[behlinla]

Well, that data is showing the engine is operating in open loop (OL) because of some fault. You should have some other codes besides P0171/4 that will tell you why there is a fault. Please post all codes in numerical form.

Idle RPM is low for some reason. Check/clean the throttle plate, and you should take the IAC off and have a look. If it looks really dirty you should clean or replace it.

[routerman]

Those are the only 2 codes. The P0174 is first and then the 171. I kind of suspected the IAC originally and did clean it as well as the TB as I'd read some before posting. I disconnected power to the IAC and nothing changed before or after cleaning it although I wasn't certain I should see a difference with the power disconnected but may just replace it. The low rpm happened during the data collection and I was just doing a manual capture without any trigger and got 20 frames and posted the first frames information. I had to keep tapping accelerator to keep it running while I did the capture. The original post of information was from the P0174 error and occurred while it was being driven.

[behlinla]

When you disconnect the IAC, the idle should drop to about 500 RPM. The face that you didn't see a change either means the IAC isn't working or you have another large vacuum leak causing your problems.

Even so, a vacuum leak should not really force the PCM into open loop operation unless perhaps is was a large vacuum leak. It's possible you might have a bad PCM if you can't get the car to go into closed loop.