Major Engine Malfunction, Can't figure out??? HELP!

[Silverwolfmike]

Hello, first time here, on my sons behalf. Im trying to help him fix his focus, and I am totally baffled. First off, heres the parts I've tossed at it trying to find this. Also, it throws no codes until the point when it kicks and dies totally, we will get there. It has a new fuel pump and filter. I can here it run, and it pressurizes the lines, so I assume it good since its new. My scan tool is enhanced ford, but does not read fuel pump pressure, only duty cycle and voltage output. So cant tell pressure. Should be good. Runs great cold. Also has new coil pack, plugs and plug wires, cam sensor, and cleaned the mass air flow sensor, looks like new. Tried a new throttle position sensor today, but it was defective or wrong model because it made it rev to 3000 at idle, and was spring loaded, original is not spring loaded. So will get a new one when stores open Tuesday. I suspect this could be the issue, but again cant tell scan tool doesn't help much here.

Now the problem. Starts fantastic, runs smooth and real good, totally driveable. Note rpm seems to drop slow, if you ask me, takes a couple seconds to come down. After about 5 minutes, or when some engine warmth starts to build, the throttle starts to bog down past about 2000rpm. If you accelerate real slow it will revv all the way up, but drive normal and it bogs out and you go no where. The car is not driveable at this point. It will idle, but wont rev up, bogs out like not enough fuel. As it continues to heat up , at side of road it gets worse quite fast. Soon you have to hold the pedal slightly to keep it running real rough. Again, real slow acceleration and feathering will get it to rev up, but then sputters and bogs again. Once up to about 215f temp , from trying to keep it running at side of road, it will totally die if you let of the tiny bit of pedal keeping it going. Then within 5 minutes it starts missing and totally dies. Then a code is through saying it missed. and a lean mixture code as well. Let it cool down. Its fine all over again , for 5 minutes, then repeat. Crazy, I can't narrow it down. TPS is my next part toss, gotta wait until Tuesday though.

 

[Silverwolfmike]

"Crickets"...… Does anyone ever come to this forum? Really need help, please. My son is stranded, no busses go to were his work is. I'm spending a fortune throwing parts at this trying to help him. I'm running out of options, no way he can afford a real mechanic. Please help, there must be a focus mechanic out here some were...

I have read that the upstream( right up high on the cat converter) takes over control of fuel management after the car warms up. My son says he changed the O2 sensors, but couldn't get that one undone, so left it. I think its toast, as it red lines on my scanner, but no codes. I've never seen an O2 sensor cause that bad of engine running before. Mainly bad fuel mileage, bit of a vibration at most. This totally screws the motor and eventually when hot it wont fire right at all. Could an O2 sensor really do this?

My next steps if I can't get guidance is to put a new Throttle sensor in that works, since the new one was no good I still don't know if that was my issue. Then I will try the expensive oxygen sensor. That will get me up to date on my research.
I did read that the cylinder head temp sensor can cause issues, but mostly with over heating since it controls the fans. I don't over heat, and the fans do come on to cool it down when it gets over 215f. Only reason I post this is for info, and I also read there is supposed to be a slow speed mode for the fans, but mine only seem to come on one speed, and only when its hot, or if you use AC. Which we don't, its unplugged to eliminate it from any possibility of being part of my sons issue.

In research, this seems to be a very common issue with these cars, although I read a few different solutions that didn't help me. Most common the fuel pump. I actually have put 2 in, since I couldn't test pressure, and wasn't sure if the new one worked since the issue is still there. I must have good pressure, I can here the pump, car off if I disconnect a fuel line it explodes with pressure and blasts me, so it has pressure, enough I can't tell. Could my code reader not be reading fuel pressure because the fuel rail pressure sensor is bad? Or does ford not provide this signal in the CPU? It does baffle me a bit that the pressure does not get listed in the sensors, but duty cycle and output voltage does??

Can anyone help me please

 

[Silverwolfmike]

Having much better luck on the other site, but keeping my options open. Today I got some new parts to toss at it. Put an upstream O2 sensor in, now both are new. Tried another aftermarket Throttle sensor, different brand, and it too failed and made 3000rpm idle. So looks like ford is the only one making exact replacments. I notice all the aftermarket ones are spring loaded, the originals are not. I don't think this is my issue anyway, but will goto ford and get raped on a new one as a precaution unless my next guess works. Lots of new sensors, no luck yet. I have the crank sensor but havn't installed as its unlikely too since it still runs. But it will go in. My son found and article about this issue, says the Idle Air Control valve, located on the intake manifold below the throttle body, on the motor side, darn it. Out comes the intake manifold. Gees. Anyway, they get dirty and stick, not allowing air to pass on acceleration and stalling motor etc. Ugly to replace, but it seems totally like the issue. Lack of fuel or air, fuel seems unlikely given the parts I put into it. Also, when I saw the article it made me think of something I thought was odd at the time, but dismissed as none essential part or not involved. Earlier in the post I mentioned I repaired the PCV line kink problem when I was looking for vacuum leaks. Doing this, I cleaned the PCV valve as instructed, and wanted to see what it did, so I started it up holding that in my hand, instead of in its hole. It did what it should, the flapper sucked up and restricted vacuum to its set limit. BUT, I smacked the throttle to see what it would do. I of course expected it to suck more, but instead it fell flat on its face and blew the flapper all the way until it plugged the other end that's supposed to be open( all the little holes), then smacked back and forth as if blowing then sucking repeat! So it made me think maybe that valve is stuck and wont let air pass, blowing it back out the PCV line. Also, I ran with that line blocked with a hose plugged at the manifold before I fixed it, and it blew off when it was stumbling. And there was no backfire. Does this make sense? I think my son may have found the issue. Big job, so gonna be a couple days to give you guys results. What do you think? should I replace it ?