Hi, I have a 93 F-150 XLT, V8 w/ an anuto transmission.

Anyhow for the last couple years the truck has run pretty crappy, not exactly sure whats wrong with it or where to check.

What it does is when your sitting at a light, and if you give very little gas the truck will want to stall, or it will stall. If it doesnt stall it will stumble pretty badly at times.
Basically I have to hang back let traffic go so I can give it enough gas from a stop light to keep it from acting up.

A check engine light is on, I took it to autozone and had them scan it and it came up with an EGR code, from what I have seen and read a EGR code should not effect performance so I am not sure where to look. I have changed the plugs and wires and nothing has changed at all.

Any suggestions on where to look would be appreciated.

Thanks
Rich

 

The EGR could affect performance but how much depends upon the code you got, post it if you know it. If you don't know it you can pull the codes with a simple procedure. Ground the STI wire in the EEC test connector harness to the neg battery terminal, turn the key to run, count the flashes on the check engine light and write them down. They will be flashed out in the sequence described here... Ford Fuel Injection.

The symptoms you describe could also be related to a vacuum leak, it's not uncommon for the plastic vacuum lines that go around the motor to become hard and brittle, and the metal vacuuum canisters rust out, these are things you should investigate.

 

Thanks for the replay, I started replacing the vacuum hoses tonight.
I was thinking about getting some of the seafoam and trying it, anyone have any feelings towards that?

 

OKAY here are the codes

KOEO
11

CM
(31) PFE or EVP circuit has intermittently failed below minimum voltage of 0.24 volts.

(33) EGR valve opening not detected.

(41) HEGO sensor circuit indicates system lean (right side).


I had the egr disconnected so im sure the 33 comes from that, but is the 41 from a bad O2 sensor??

 

Oh and another thing is just grounding the STI didnt work for me, i had to connect the STI to the SIG-RTN

 

How did you disconnect the EGR valve?
It sure sounds like an open EGR valve to me.
To check it, if the valve is still on the engine is to take the large line off the bottom, drop a penny in the tube and screw it back on but not too tight to deform the tube or the seat.
Run the engine and see if it runs differently.

Then remove the penny.

What engine to you have (302, 351 or a 460)?

 

I just had it unplugged and the vacuum signal unplugged, I plugged it all back in today. I am gonna reset the codes and see if the same ones come up.

Does the one code mean I need a new o2 sensor?

The engine is a 302

 

Not necessarily, it could be the EGR valve open giving this lean code.
It would also run like this.
Try the penny and see what happens.

 

Not always. An O2 that reads lean, could mean the engine is running lean, not just that the O2 sensor is bad.

 

Anyway to tell for certain without buying a Wideband O2, or changing the sensor?

 

How come you will not just drop the penny in for a test?

 

To test for the lean condition?

 

Bill, what does the penny do?

Rich, is the EGR stuff still unplugged? If it is, plug it back in.

 

Mostly for the way it is running but it may fix that too.

 

A penny is just the right size to block the exhaust gas from getting to the ERG Valve.
I blocked my EGR off at the flange and was getting a code 334. After dropping a penny down the tube the code went away.
I think what was happening is with the EGR flange block off the exhaust gas was strong enough to raise the EGR valve off its seat and give the 334 code.

So in this thread I figured that a penny in the tube is a quick way to eliminate the EGR valve as the cause of the problem or confirm it.
You just unscrew the big tube on the bottom, drop the penny in and screw it back on but not too tight to deform the seat or the tube.