Hey all - I've been fighting a surging/miss/hesitation for a while now. 96 E350 van. I've replaced in the past 6 months:

Plugs/wires/cap/rotor (all Motorcraft)
TPS
Fuel filter
MAP sensor
Coil
Ignition module
Fuel injectors
Most vacuum hoses
EGR Solenoid valve (the old one showed no change with 12v, smelled burnt)

Fuel pressure checks OK, pump is less than 2 years old.
Checked the timing - spot on.

Code - 332, "insufficient EGR opening."

The EGR valve SEEMS to be working, and it only gave me the check engine light after we replaced the injectors - seems that we broke a hard line while reinstalling the tranny dipstick tube.

Now that the vac lines are fixed, there's no CEL. It starts fine, idles a bit rough, but that's being picky.

When COLD, it runs flawlessly.

Once warm, slight uphill grade, in OD, going ~55ish (any speed, really), *light* throttle results in a bucking/surging/misfire.

My question - could those _symptoms_ be a bad egr valve?

Stick your foot in it, or turn off OD, get the revs up a bit, it "drives through" the stumble - but maintaining highway speed, it surges and bucks just a little.

It is not unusable, but it is a bit annoying. Taking the EGR out of the van is enough of a pain in the butt that I'm tempted to throw a new one at it if I get the old one out.

Thoughts? Mostly on the symptoms. I've not changed the EGR position sensor on top of the EGR, but it tests OK. Everything else seems fine. Could a faulty EGR cause this kind of drivability issue?

Thanks!



Iain

 

I just went through a similar search. Coil sparked fine turning over, but under load it would buck and kick, in the end it was the coil on my 1992 302-5.0 E150. $20 bucks at ORielly's and its not missed since.
just a thought
Andrew.

 

Thanks, Andrew - knew I forgot something.

Add "coil" to List Of Things Replaced. Oh, fuel pressure regulator, too.

Kinda has to be the EGR valve, I think....



Iain

 

Sounds like the egr ports in the intake are clogged. Just cleaned mine and I had the exact same issues with lite throttle being applied. Smash the gas and it ran like a raped ape. Do a search for "P0401" and it should come up with a few ideas to try.

In order to clean the ports you do need to get into the intake......

This was the fix for my '01 4.2L...after changing alot of parts like you.

 

OK, an update.

The new EGR made no difference. I've run two cans of Seafoam through it. There's no evidence of clogged ports - the only port is the hole in the intake plenum, and I'm fairly certain that's not clogged.

Changed the cap to an Accel - the Motorcraft fit poorly. The Accel fits nicely. The contacts on the MCraft were _white_, a powdery residue. Surely that's it....nope. New rotor, too.

Tried a different ECU - out of a 93 E250, 5.8/E40d. The van runs *differently*, but the problem still remains. Going to put the original ECU back into it.

I'm kinda thinking coil - even though this coil is new (3mos old), it sounds like Andrew's problem - the only thing that seems weird to me is that if I stick my foot in it, the van clears out and goes OK. I'm not sure of the brand of coil - the mechanic replaced it when he checked the fuel pressure - it is white and does not fit well in the metal piece that surrounds it. Cheap and easy.

I've also got a reman distributor waiting for me at the auto parts store, and I'm going to pick up a new coolant temp sensor. I believe that the fuel injection goes into "open loop" (or is it closed?) at FULL throttle, thing is, 3/4-7/8 throttle is enough to clear it out - the miss/hesitation is just at part throttle, like 1/4-1/2. Add a chunk more (like to 3/4) it goes pretty much OK.

I'm not sure what would be wrong in the distributor, but I do see that auto parts stores sell the hall-deal to go into the housing - the store near my house stocks it - so....maybe?

I really need to get this thing fixed. Maybe a vac-leak on the lower half of the intake? I'd think that'd ruin idle - it idles pretty well, maybe a slight ignition miss. It does not seem like it has a vac-leak - no whistle, it has not stalled once, no elevated idle, shrug, I've had many vac leaks in the past (on other vehicles), and this does not seem like one.

Air temp sensor for the FI? Might pick one of those up, too.

Current plan is coil first, drive it. If not fixed (I doubt it.....), then distributor/coolant temp sensor/another set of plugs, drive it. If not fixed (man, I hope so....), fuel pump - even though the fuel pressure was rock solid while driving, it does FEEL like a failing pump. That said, you'd think that the problem would not go away with WOT or close to it.

The good news is that when it is all said and done, it should be reliable for a long time......



Iain

 

Are you still getting the same code for the EGR?
You can try unhooking the vacuum line to the EGR valve and plugging the line.
This should keep the EGR valve closed and then you will know it is not the EGR valve not closing all the way. I know the code is for opening but a closed valve will not cause any problems.
That EGR code is caused most of the time by a bad vacuum line from the EGR solenoid to the valve or a bad EVR solenoid.

Yes you will go to open loop at WOT.

 

No code since; the EGR system _appears_ to be functioning correctly.

Does it go open loop AT WOT, or somewhere above x% throttle? I always thought it was _at_ WOT.

Could the junk inside the distributor start getting weird with heat/load/light throttle?

I just KNOW it is something stupid and I'm missing it. I had a similarish problem on an Audi many years ago - it ran like crap. Replaced everything - fuel delivery stuff, ignition stuff, everything. Found that it was blowing the FI fuse. Replaced fuse several times, eventually realized that it'd blow the fuse at ~4500rpm.

At the end of my rope one day, I was lying under the hood, revved the motor to 4200....4300...4500, pop, fuse died, goes into "FULL RICH" mode, hmmm. Replaced fuse, did it again. Out of the corner of my eye, I saw movement.

The spade terminal that is swedged onto the full throttle switch was loose. At 4200rpm, it'd start to vibrate and rotate. By 4500, it'd rotate over & short out on the bracket, popping the fuse.

Punch and hammer, one tap, one more fuse, that car was rock-solid until I sold it.

It drove me almost this nuts trying to _find_ it, though.....


Iain

 

The Computer reads three positions from the TSP. They are CT (Closed Throttle), PT (Part Throttle) and OT (Open Throttle).
The computer will go to Open Loop when its math say it is at OT. It takes the CT voltage when the engine is started each time (0.6-1.2VDC) and this is why you should never touch the Throttle when starting the engine. It then uses math to come up with the PT and OT ranges of voltages. If the CT is not in the 0.6-1.2VDC then the math will be off and it may not ever think it is at OT. The Throttle may not have to be all the way open to be be in OT.
I like to see the closed throttle position to be about 0.9VDC. So the closed throttle position voltage will determined at what voltage the computer thinks it is in OT (some where less than 4.95 VDC).

 

I am going to refer to a similar issue with my 89 5.0 Mustang and the salt and pepper shakers.

The computer and electrical connectors on my Mustang for the motor are at the back and are black and white, hence salt and pepper. The white connector was causing similar issues with my Mustang as you are having with your van.

Check the electrical connectors as well, I cleaned them up and put a light coat of dielectric grease in to prevent further corrosion.

 

Thanks! Will look - what do these connectors do? Roughly speaking - I can't think of any white/black connectors off the top of my head.

I guess I should un/plug everything I can find, so far, they've all looked ok, but I've not looked at _all_ of them.

Thanks!


Iain

 

These are all the sensor connections! If these signals go off the computer cannot function properly!

 

I do not think that the PIP sensor is your problem.

 

PIP is just hall effect, basically, correct?

If it is, I don't think it is the issue, either - but I've tried just about everything else.....


Iain

 

Yes the PIP is hall effect switch and op amp on the distributor stator.

 

Found it.

Finally.

Cracked spark plug ceramic on #1 cylinder.

Long, long story, but basically. I changed the plugs (all of them) about a year ago. Preventative maintenance. I did cap and rotor at the same time. I can't remember if the miss started before or after that.

Chasing the miss (and I forget timeline), I replaced a lot of stuff. Fuel filter, verified fuel pressure, egr system, vac lines, injectors, throttle position sensor, cap rotor plugs (6 of 8) wires.

When I replaced the wires and 6 plugs, I had started on the easy side and worked around to the hard side. Got to plug 7, found a torn boot. The plugs that were coming out had maybe 2k miles on them, the torn boot "has" to be the problem, right? Replaced the wires, left the two plugs - including the #1 cracked plug.

They were the 3rd set of plugs - originals (wasted, but it actually ran pretty well on them), new ones (seems that I cracked one on the way in), then I replaced 6/8. I wish I could remember when I put _those_ plugs in. I've changed a LOT of stuff since.

Thank goodness. I have to go return some parts now. Yay!



Iain