Hesitation EGR

I am having a continuing problem with hesitation. I decided to check into the EGR Valve. I disconnected the vacume line to the EGR valve and plugged it and took it for a ride. Less hesitation and no loss in power. I put the line back on and it made the idle a little worse. Checked for vacume fro the line and got Zero at idle and about 3 above 2500rpm. Thats seems low to me. I then hooked a vacume line to the egr and sucked through it and it caused the engine to die. My understanding is that the EGR does not function at idle or when cold but after it gets warm it should open up above 2000rpm. The fact that it runs just as well or better with it disconnected makes me think the EGR valve is not closing all the way. Also what should the vacume be at 2500rpm in park. (96 3.8 litre) (Edited) I decided to try first thing in the morning cool engine cool and the van seemed to run well no hesitation. The more its driven the worse it gets. On the highway last night it would hesitste on acceleration until I reached my speed. When I say hesitate its not like there is no throttle reponse its almost like the van is getting no spark or gas momentarily. It may hesitate 5 or 6 times trying to acheive speed. It causes a bucking motion. I read on line about how some cars have a grounding problem and it causes this. Anyone ever heard of that? It is not a miss. Thanks

Sure sounds like a gummed up EGR to me.

If you are reading vacuum on the vacuum manifold ... your readings are too low. I would look for a vacuum leak of some sort. Adding the EGR vacuum chamber, just adds to the vacuum "demand" ... making the system a little less responsive. The question is:" ..does your EGR possibly have a vacuum leak?"

If I understand your EGR test correctly, the EGR sounds okay. But, when you had a vacuum pump on the EGR, did it "hold" vacuum ... indicating no leak on the EGR diaphragm?

You might try unplugging and capping all vacuum loads that are not necessary for running ... just as a test.

The vaccum to the EGR valve, when the PCM calls for it to open, will be MODULATED.
The DPFE will measure the EGR flow....and the PCM will use this measurement to modulate the EGR valve to match the DPFE reading to that value that the PCM is looking for.

IF the EGR valve is stuck, I would expect an error code indicating a EGR flow as measured by the DPFE, when it is not being called for.
Perhaps a DPFE is getting marginal?....but that is only a guess.....but as they are somewhat a high failure item (more so than most any other EGR component.....not counting clogged EGR ports), you might try replacing it....and you will know for sure.
This is all sounding like something is marginal.....not totally failed.....and that is what is making this a hard problem to track down.

Of course......you know....but I mention for anyone getting the message from a search function.....
Disconnecting the vaccum line from the EGR valve......disables the EGR valve, so you should get a CEL, and a code indicating insufficient EGR flow.....as the PCM is not able to open the EGR valve.

12Ounce
I just sucked on the end of a vacume tube and it drew in the diagfram. The funny thing is I can tell it is sucking in the egr at idle a little because it starts running a little rough. If I un plug from the egr and plu the vacume hose or not the idle gets better. Do you know if your supposed to have manifold vacume 15 to 21 at the egr when the pcm tells it to work or should it be abot 3 to 5?

wiswind
Thanks for your help with the cooling fans Im not sure how long I have not had low speed the parts on order. Now if I could just fix this hesitation Id be happy. I have replaced the dpfe a year or so ago. I suppose it could be bad. No codes.

12Ounce
No I was not reading that at the manifold but from the vacume line connected to the egr valve. Is there anyone who could check there vacume at the line to the egr at about 2000 rpm and see what the vacume should be I would greatly appreciate it 96 3.8 Ive looked for a base line everywhere on alldata the discs and service manual. Is the egr solenoid just a open or closed valve or does it act proportionatley to the dpfe?

I have never made that measurement....but I am guessing that it would not be 15 to 21......as you have noticed....it does not take a whole bunch to open the valve by sucking on it.
You could, use your Mightyvac pump.....if you have the one with a vaccum gauge on it......and pump it up to see how much vaccum it takes to pull the egr valve open.
Another check.....would be to put a "T" into the end of the vaccum line to the EGR valve......and add a small section of vaccum line to connect the EGR valve.....then run a LONG vaccum line into the passenger compartment....connected to your vaccum gauge....and go for a drive.
If you do this......I posted a couple of pictures that show a good way to run a line between the engine compartment and the passenger compartment.

I imagine the vaccum to be a fast pulsing (vaccum gauge likely will only show an average value....but good enough).

Just some information I thought Id pass on about the dpfe, egr solenoid and the egr valve. The egr requires 1.6 to open and no more than 5. I found these articles. http://www.tomco-inc.com/Tech_Tips/ttt35.pdf http://www.tomco-inc.com/Tech_Tips/ttt36.pdf http://www.ford-trucks.com/forums/414647-dpfe-voltage-testing.html Wiswind was right the dpfe as well as the egr solenoid and pcm tell the egr valve when to open. It also explains a little vacume is put to the egr at idle slightley opening the egr. Im not sure why because at least with my van it causes the idle to be a little rough. I still though have not found a solution to the hesitation problem. I may try Wiswinds idea about the dpfe I just hate to replace it again only about a year later. I have the newer style plastic.

I also wonder about the EGR vaccum solenoid if you are getting enough vaccum to open the EGR valve at idle.
I recall a very slight vaccum.....but I didn't think it was enough to open the valve.....certainly not enough to cause rough idle.
You could try cleaning it with SeaFoam.....spray some (just a bit) into the vaccum input....where the vaccum line from the EGR valve goes.
I also read a post about the little air filter inside getting dirty.....The air filter for the vaccum solenoid is located under the "cap" that is on the top of the solenoid......you remove the cap....and there is a felt filter in there.....clean it...and re-install.

To get at the solenoid you almost have to remove the upper intake correct? Or does it unclip from the back of it? Idont remeber. Try unplugging your vacume line from the egr and see if you hear or feel a difference. I do just a little rougher you do hear it. I will try cleaning it as you say though.

I have never tried to remove mine....so I don't know.
Alldata mentions removing "retaining nuts" to remove the solenoid from it's bracket.

An update. I was home today and decided to take the Windsar for a drive. Early morning 6:00. It was about 65 Degrees outside. I drove it until it reached operating temperature. No hesitation. Drove it for about 20 minutes. No hesitation. A couple hours later I took it out again until it got up to operating temps drove fine one hesitation or rough shift? Agagin 15 or so minutes I drove it back no problem. Took it out again a little later it had not really cooled down yet and the outside temperature had increased to 75 or 78 degrees. Plus the sun was out the hood was hot. It started hesitating bad. It seems it has something to do with the ambient temp. Just thinking out loud. Could it have something to do with the fact my low speed fans arent running and something is becoming overheated? Or is the air temperature switch having an effect? Is there any kind of ambient temperature monitor? I have noticed to it has happend when the engine was cool and hot out and the car baking in the sun. Not sure if the coolant temperature was warm enough to still open egr. I just thought it was interesting. My dropping resistor comes tomorrow so I might be able to answer my own question. :banghead:

The ambient temperature sensor is located inside the big black flex hose that goes from the throttle body to the MAF / Air filter box.

I think I posted a picture that shows it...but if not....it has the ONLY electrical connecton on the flex hose.
You could try cleaning it with non-residue electronic cleaner, or "MAF cleaner".

Don't you just "love" a intermittent problem that sets no code?
I have wondered about my air temperature sensor and my coolant temperature sensor (computer uses a different sensor than the gauge does)....and that is one reason that I chose the "Scangauge" code reader.....as it is small......and has a gauge function....that you can select certain parameters to monitor as you drive.....air temp and coolant temp (as teh computer sees them) are 2 choices that I have monitored....and verified that mine are good....and stable.

wiswind
Thanks Wiswind. I was wondering if there was some sensor in a different location. I know about the iat it sends info to the pcm and tps. I was thinking that somehow something was getting over heated. How about the coil pack? Or could the ect (engine coolant temp) sensor be giving off bad readings? It has something to do with heat and when the engine is warm. I thought I had replaced the the ect but I looked today at all parts I replaced and I installed the old one. Its worth a try. Your right without a code your just guessing. I figure any part I replaced that didnt need it is one less part to replace later. At 190,000 miles its not a waste.

Just an update. I tried changing the coolant temperature sensor no change. I also read about a plug by the pcm called a sprout. Removing it it retards the timing 3 degrees. To check timing you remove it. Removed and no change. Still want to test out the egr vacume solenoid and egr. Was hoping my dropping resistor would come. No such luck.

Another update. Well so far I have replaced the 2 upstream O2 Sensors, TPS, TRS, Flex pipe, Coolant temperature sensor for the computer not gauge. Cleaned the MAF sensor, Replaced the coil, All plugs and plug wires done with intake manifold gasket change and egr port cleaning in May. New pcv, New fuel filter, New air filter,

Thought I had it licked a couple of times. Today I replaced the coil and found two corroded contacts on the wires connecting power to the coil I sprayed contact cleaner and cleaned no luck. The MAF sensor you can leave unplugged to rule it out the TPS and IAC adjust and componsate temporarily. Ithought for sure it was the coolant temperature sensor because it seemed to happen only above a certain temperature. That didnt work. If you floor it it will take off without hesitation no bucking lots of power. There does'nt appear to be any back pressure problem vacume test all appear normal. It seems that there are only two other possabilitys. EGR or EGR solenoid or DPFE which I replaced about a year and a half ago.

Im going to bring it in and have the trans looked at because its shiffting hard and clunks when its coming to a stop like the torque converter isnt letting loose until the last second. Thre very good at diagnostics. I had aproblem with 96 Blazer trans it wouldnt move. They checked it out and it ended being the ignition switch. They could have told me it was the trans and I would have probabley agreed. So Maybe they can figure this out. With all the money I have spent on all these parts I could have bought that Autoenginuity scanner Ive been wanting. Oh well. All the parts had 190,00 miles so It isnt all wasted money. Let you know if I figure it out. Any ideas please post.

Update No more luck with the hesitation. Tried the egr vacume solenoid and checked egr. No luck. Tried replacing the maf sensor no luck. I only have one other idea. There is a tsb that relates to the 96 usually showing a miss. Article 98-25-5 One solution is to program the pcm. I probably need to do that anywys as I get a flashing trac on light. A tsb for that says to reprogram the pcm. So I might bring it in or just the pcm and have the latest calibration. Ill let you know.

Another update with good information this time. I decided to bring it in to a local shop and have a diagnostics done on it. Heres the results.

Fuel trim excessivley high on both banks.
As a result it is running very lean. Injectors 2 and 3 are bad. I have run numerous cans of injector cleaner with no luck. Mechanics opinion replace all the injectors. I thought about doing that when I was doing the gasket replacement but just replaced the Orings.

They also scanned the rest of the vehicle and did a smoke test to find vacume leaks. There was a small hole in one line that rested on one of the coolant lines on the back firewall. Easy fix. Not enough to cause any problem.

Showed a bad vss. Though I dont have any speedometer problems. (Yet)

There were two codes for the traction Control U1027 U1009. Both relate to the reflashing of the pcm which I had him do.

Also I have a C1446 Brake switch failure. ??? Wiswind I know you have mentioned people check theres.

Also a C1148 Front wheel speed sensor fault. I dont have any abs problems?

Also he reccomended the isolators be replaced. Not sure why as they are not subject to the same problems as the later years.

The plan then is to order 6 injectors. Brake switch. Isolators. Vss.

I only wish I had purchased the Autoenginuity scanner all this info I would have got for free. However the explanations and info I recieved from the mechanic was worth it.

I would reccomend anyone with a problem they can not solve by themselves or through this forum have a scan done of your vehicle it is invaluable.

I hope when all is said and done though that the problems are solved.

Further updates will follow. Thanks for everyones haelp.

Final update. Hesitation fixed.:) :) :) Finally found the problem. It ended up being an intermittent problem with the fuel pump. The funny thing was that I tested it a number of times and while it was on the low side of normal it was in range. The thing that clinched it was a test with the engine off and ignition turned on the fuel pressure should have been about 35 lbs. It read about 12. If you turned the ignition on and off it would get about 25 lbs. It was only after taping the fuel gauge to the windsheild (cowl removed to make it long enough) I discovered the fuel pressure dropping at the hesitation points. Even though it was hesitating it wasnt until it progressivley got worse I was able to figure it out. There still were 2 bad injectors that were messing up the fuel trim according to the guy who diagnosed it. The real culprit was the fuel pump. I ended up having it done because it was $450.00 the tank was full and if I had a lift it may have been a different story. Well lots of new parts. I should be set for ahwile. Im not quite sure it was all worth it. New intake gaskets, radiator hoses, cap, thermostat, plugs, wires, coil, tps, ect, ccrm, ait, trs, fuel injectors, dropping resistor and driver side window regulator and motor. Not to mention new tires, front wheel bearing, rear shocks, breaks front and rear dpfe, brake switch and lower control arm with in the last 8 months. I hope to go a few more years now in order to get my moneys worth. Thanks for all the help and suggestions.