if me and the o2 is from day 1 and cheap enough I would just replace it.

as for vacuum leak check have you done the smoke test?
look it up on YouTube, easy to do too.
Dave - - - -

 

I have had the truck about 6 years and the o2 has not been replaced in that time but before that i have no idea since i am at least the 4th owner. I will check out the smoke test, i appreciate all the help.

 

After watching the YouTube video, this link tells how it worked for me: https://www.ford-trucks.com/forums/1...expensive.html

 

Thank you. I have the O2 sensor out and once thats replaced if needed i will do the smoke test. The O2 sensor part # prefix E3EF threw me since that would be for an 83 model and in looking around on here that would be for (Cab over Engine) (1970-73), Pinto (1976-80), Escort (1981-later)
F = Foreign sales / Trans Am Racing...............very confusing since i have a 1985 f150 5.0.....morph.....has the paper cartridge fuel filter/no inline and no schraeder valve on fuel rail.

 

Replaced the O2 sensor and no more code 13 but truck still has idle surge and runs crappy. Rescanned and came up with even more codes some of which i assume are because at throttle depression during test the engine hesitates and cuts out. 44 (thermactor air system failure) 34 (pressure feedback sensor voltage is high) 72 (insufficient map/maf baro change during goose test) 73(insufficient throttle position sensorchange during goose test) Why did all these new codes all of a sudden show up? I have not done the vacuum leak check yet.

 

Ok I am no expert but it looks like the MAP/MAF and maybe the TPS is bad.
Then again it is telling you there was not enough change and could be "because at throttle depression during test the engine hesitates and cuts out."
What is the code 34 (pressure feedback sensor voltage is high) What PSI is it measuring? Could it be fuel PSI and have you put a gauge on it to see what you have?


I would try and clear all the new codes and re-run the test again to see if you get the same codes.
Dave ----

 

44 is the air pump system, I would ignore that for now. 34 is your EGR sensor. I would temporarily take the EGR valve off, make a block off gasket out of a pop can or some other thin metal, and put the egr back on with the homemade block off. Then try it. If it straightens out, then you have EGR problems.

You are probably correct on the other codes, when the test told you to goose the throttle if that didn't happen you will get some other error codes.

 

Trying to learn this stuff so if I ever get a EFI truck I will have half a clue.


So that code 34 is it because the voltage to open/close the valve is to high or the PSI in the EGR track to high?
I did not think they checked the track PSI but I don't know this system too well.


Other question does the valve work by vacuum or electric? If vacuum where does the ECM get its signal from?
Dave ----

 

Ford had a couple of different systems they used for the EGR. On these trucks they usually used the transducer type. It consists of a electric vacuum solenoid which controls the vacuum to the EGR valve which works like the old conventional valves with a large diaphragm in it. But on top of the valve is mounted a variable resistor or transducer that is mechanically hooked to the egr valve. When the computer decides it's time to add some EGR, it sends a signal to the EGR vacuum valve, and then quickly looks at the signal coming from the transducer. It should see a change in the voltage from it as the EGR valve opens. It keeps going back and forth like this, modulating the EGR position for the max amount of EGR the engine can take at that particular time.

The other system they had is the pressure transducer type. This is the type they use on my little ranger with the 2.9 v6. This type also has a electric vacuum valve. It also has a conventional type EGR valve with a diaphragm. What it has additionally for feedback to the computer is a pressure sensor located off the egr supply line to the exhaust manifold. The supply line to the EGR is usually a large steel pipe, and off of this that have a small fitting with a line going to a little pressure sensor box.

Normally the exhaust system has backpressure as it's running down the road. The back pressure builds in the EGR supply pipe. The pressure sensor is reading this back pressure. When the computer decides it's time to add some EGR, it sends a signal to the vacuum valve which supplies vacuum to the EGR. The EGR opens. When it does, the pressure in the exhaust supply line will drop. The sensor sends this signal back to the computer. The more the valve opens, the more the pressure will drop. Like the other system, it constantly goes back and forth to modulate the EGR flow rate.

They use the same code for both systems.

 

So the way I understand this one system if the valve is too hard to move (stuck) would throw a code and the other if the exh has too much PSI will seta code.
Am I close?
Dave ----

 

Yes. The first thing is when the engine starts, it is not opening the valve so it expects a certain voltage reading from the transducer because the valve should be closed. If it gets a voltage reading it doesn't like, it will set a error code. You are correct, if it gets hung up, the valve will be in the wrong position, the sensor will be sending out a improper reading, and it will eventually set a error code.

Here is a link with the codes. If you go down the list they show 3 different egr systems, I am only familiar with the two I mentioned. And it shows all the different scenarios and the different codes that can be set.

EEC IV 2 digit codes

The pressure sensor type system gives a lot of trouble. Of course it's sampling exhaust gas, so that is hard on the sensor and it has a high failure rate.

 

Have you replaced your plugs, cap, rotor & wires?

Have you checked your timing ?

 

sorry i havent gotten back to everyone, have been sick. when i feel better i will work on it again. thank y'all for your help.

 

Yes cap,rotor wires are new and finally was able to check timing since the truck now idles good.

 

I have replaced the tabp, the oxygen sensor and found a broken pcv valve. Truck now idles great but hesitates and seems underpowered under load. I now only get 2 codes, the 44 for thermactor system failure and 34 pressure feedback egr sensor voltage is high. My next course will be as Franklin suggested and block off the EGR and see what happens.