OK, This was my first opportunity to work on the truck again. The egr valve looks almost clean as a whistle. No carbon buildup, just a small amount of dust that would be rather expected. I do not think this is the problem.

The diaphram within the egr valve is holding vacuum.

Oh BTW: "If we knew that, therein may lye a good clue to the EGR code he's getting!!!" HE is SHE.

Andi

 

I further searched the forum and came to the conclusion that the ports on the back side of the throttle body "could" be clogged. I have not attempted the removal as of yet because I can't find the replacement gaskets. All places say they must be ordered and will be around a week before they arrive. Even the dealer does not stock theses gaskets. How important are these gaskets and can sealant be used instead. I have 1 more day off to work on this or it will be next Saturday before it gets done.
Andi

 

Dang Andi, seems pawpaw has made a faux pas!!!! lol So we have a lady wrench turner here, thats good to hear. Your not alone though, we've hade several successful lady wrench turners stop by on the MotorWeek forum, that were persistant, determined & as such, managed to fix things that several shops had given up on!!!!

Good EGR testing & feedback & to hear the EGR valve is clean & it's diaphragm is holding a vacuum & seems to check out good. So I suppose we can set a faulty or carboned up EGR valve aside for now.

Have you tried pulling & plugging the EGR valves diaphragm vacuum control line, to disable the EGR valve, then driving the vehicle until it completely warms up, then do the acceleration test at 40 mph & see it it'll buck????

Maybe this will tell us if you have other than EGR control problems too.

Seeing as how your bucking problems seem to be temperature sensitive (not there all the time) I doubt you have throttle body problems.

Anyway, try disabling the EGR & let us know how the bucking problem responds.

 

OK, I did this and the truck runs really bad. Its almost like its running on half its cylinders. It spits and sputters really bad. This happens whether cold or warm. At idle it feels like its about to die and runs really rough.
Andi

 

OK, when you pulled the EGR vacuum ine loose, did you plug it???? Did the plug stay in place???? If not it'll act as a bad vacuum leak & the engine will run rough.

 

I don't think I plugged it off, so thats why it ran so rough. I will do this again tomorrow. Right now its 27°F and its snowing.

The only reason I work on this truck and am so persistent is I am the only one I can afford to pay to repair it.
Andi

 

Hey roger on the afford part, thats how I came to turning most of my wrenches, then I discovered how easy & how much fun & satisfaction it was, to fix it myself!!!!

Let us know how the test goes.

 

Hey Pawpaw,
This time when I disabled the egr vac hose I plugged and taped it so it couldn't come out. I did not notice any change except that the truck ran a little rougher at idle(before gear engagement). The bucking is still there when temp starts to climb and going above 40mph.
Andi

 

OK, good test Andi, with the EGR disabled, & it still bucking, it would suggest to me the EGR valve may not be the root cause of your bucking problem & you may have a EGR valve "control problem", rather than a problem with the EGR valve itself, that your P0401 trouble code suggests.

So what next to try it isolate your problem/s is the next question.

Your finding that the EGR valve looked good for deposits & it's diaphragm was holding vacuum ok, makes me want to suspect something is going on upstream, with the EVR (Electonic Vacuum Regulator) solenoid.

The computer uses a pulsed electrical signal to this soenoid device, to control the vacuum pulses/work duty cycle, to the EGR valve, which causes the EGR valve to open or close, when the computer has decided the engine needs, or doesn't need EGR feedback flow.

SO, if for some reason the EVR solenoid isn't properly recieving a pulsed electrcal signal from the computer to operate, or not properly responding to that sent signal, then the EGR valve won't respond as needed.

Seems to me you next need to check out the EVR solenoid, it's vacuum lines, gaskets, fastners, electrical connection & make sure all are in good condition, then run the fuction test on the EVR valve & it's solenoid, thats called out in your repair manual.

For instance, If the EVR has a vacuum leak in the line that runs from it, over to te EGR valve, that could cause the EGR valve not to open right & also provide a unmetered vacuum leak AFTER the engine has warmed up enough for the computer to signal the EVR solenoid, to bring the EGR valve online.

If you have a vacuum leak in the EVR, it's gaskets or vacuum lines, that weak vacuum applied to the EGR valve, could cause it to act out & be the cause of your P0401 code & the warm engine stumble, at throttle up!!!!

So thoroughly check out the EVR, it's electrical wiring & connector, mounting fastners, gasket & vacuum line running over to the EGR valve.

The vacuum line should fit tight on both ends, be without splits, cracks, or kinks. The EVR's fastners should be tight & it's electrical connector should be without damage or corrosion on it pins & sockets & plugged in/locked snug into place.

Let us know what you find.

 

Where is the EVR located? 3.0 FFV

 

Well ya got me on that one, I don't rightly know on the 3.0L, but you could try tracing the EGR valve vacuum line backwards & it should lead you to the EVR solenoid I should think.

 

Will try that.
The "book" shows an EVR but its a different model than mine.

 

For anyone else who needs to find this components location. Its on the back side of the coil pack(where the plug wires plug onto).

Pawpaw,
All the connections look good as far as a visual inspection goes.

I have a multi-meter but have no idea how to use it to check the voltages. I do learn really quick though if someone tells me how.
Andi

 

OK, well set your multimeter to the 20VDC range, disconnect the EVR's electrical connector & back probe it with the ignition switch in the KOEO. (Key On Engine Off) or the ignition ky in the "run" position, but don't start the engine. You should have battery voltage present.

Next, set your multimeter to the X1 ohms setting & check the EVR's solenoid winding, it should read between 30 & 70 ohms.
On Edit: If you have a digtial multimeter, lead polarity isn't critical, it'll read either way.
HOWEVER if you have a analog meter (one with a meter face & needle indicator) you MUST be mindful of proper lead polarity, The red lead plugs into the meters + socket, black lead into the meters - socket.
Then the red probe will go to the EVR's connector B+ socket or pin & the black B- probe will go to the connectors B- connection, or if it only has onewire to it, the vehicle chassis, or engine, clean metal part, to have it properly read the battery voltage on the EVR connector.

Next, disconnect the vacuum line at the EGR valve & gently blow into it, you should feel some resistance, if you can easily blow back through the EVR, it's leaking & not sealing properly & should be replaced.

Let us know what you find.

 

Thank you very much Pawpaw. Just went out and did the "blow" test on the vac line at the top of the egr valve. There is NO resistance when blown through. Now to go spend another $25 on a new one. I figured I would try that first as it was a path of least trouble.
Andi