Windstar 96 - High NOx Emissions

[Zanel]

Hello Everybody:
As I'm a novice to this forum, please welcome myself.
I have trouble figuring out what causes High NOx emission failure with my 96 3.8 Windstar.

It only fails under (15 MPH) test condition:
1. 15 MPH and 1649 RPM: NO = 673 - FAIL, should be 512 MAX
2. 25 MPH and 1351 RPM: NO = 724 - PASS, should be 765 MAX

I have done so far the following: EGR Valve (replaced), EGR Regulator (checked, OK), DPFE Sensor (replaced), all hoses, cleaned batterfly channels in intake manifold, IMRC Actuators (checked, OK).

Engine is NOT overheating and NO trouble codes detected.

If possible, I would appreciate a quick feedback as I have another test schedulled for coming Monday. Thank you.
--
Zanel
--

[DRW1000]

The most common cause of high Nox emmisions is too high of a temperature during combustion. The emission control system that the auto makers came up with is the EGR system.

The EGR system routes exhaust fumes into the intake stream that in effect lowers the amount of oxygen in the incoming air and lowers combustion temperatures.

It looks like you have checked the obvious:
EGR Valve
DPFE
EGR Controller
and hoses

It could be that you have clogged EGR ports within the intake. I am not too familiar with the 96s but some models have a separate port for each cylinder. They normally start to clog and then cause misfires in the non clogged cylinders. Perhaps yours have clogged all of them.

Can you manually apply a vacuum to the EGR port at idle? If so if there is flow it should stall the engine. If it offers no change then it would appear that the EGR flow is not getting into the engine. If it does run rough then perhaps the command to the EGR controller is non-existant or not getting the the EGR Vacuum controller.

I am not sure but I think an intake leak could also affect NOX numbers.

Let us know.

[Zanel]

Thanks for the quick reply.
I forgot to mention that I have cleaned all 6 EGR ports also.
Can you please share a step-by-step procedure as to how manually apply a vacuum to the EGR port at idle?
Thank you.
--
Zanel
--

[DRW1000]

On your EGR valve should be a thin tube that runs to the controller. When the PCM commands the EGR on (or open) a vacuum is applied to this line causing the EGR valve to open.

I would simply disconnect this hose from the EGR and replace it with another hose. Apply a vacuum to the loose end by using either a vacuum gauge or by sucking on it (Careful sticking your head near the engine) with the engine idling. If this vacuum opens the valve and there is exhaust flow then the car will idle rough and eventually stall.

I would think that a malfunctioning EGR system would flag a code (I can't see how itr would not) so we may be barking up the wrong tree.

[Zanel]

Thanks, I will do this procedure this evening and let you know about the outcome tomorrow morning.

Now, I understand sertain conditions must exist in order PCM command EGR controller to open EGR valve, such as: ECT sensor = 113F, TPS is in part throttle and MAF sensor is in its mid range.
What else info PCM gathers to open EGR valve?
Can VSS affect EGR system? The VSS is not working properly, speedo is not stable.
Thanks.
--
Zanel
--

[gbic1]

Usually the egr system does not work at this low of rpm range or you would have surging problems. I have not seen this test fail on your type of car but if you build up carbon in the cylinders it will increase your compression ratio and possabley increase the cylinder temperature. To clean the carbon out of the cylinders I would buy some Seafoam and with engine idling pull off a manifold vacuum line and allow the engine to suck the can empty, hopefully by flooding engine with the seafoam. Let it sit for 30 minutes than start it. Be warned if it is carboned up it will have a lot of smoke out the tail pipe when started. It would not hurt to put another can in the gas tank.

[Zanel]

Thanks qbic1:
By a manifold vacuum line, are you refering to a plastic/rubber hose line coming to upper intake manifold plenum?

[DRW1000]

the Seafoam hurting can't hurt..........

I would still do the EGR vacuum check as it is an easy check.

Let us know how you make out.

[wiswind]

I have put seafoam into the vaccum line that goes to the top of the upper intake manifold on my '96 3.8L. This is the PCV line...and a number of other things connect to this same line.

The only problem that I had adding anything to that line is that I ALWAYS had a fair amound come out the throttle body into the air intake hose.
This is the easiest place to add the seafoam....but I would add it to another location.
I have, carefully, used the vaccum line that goes to the Power Brake unit.

[gbic1]

Originally Posted by wiswind

I have put seafoam into the vaccum line that goes to the top of the upper intake manifold on my '96 3.8L. This is the PCV line...and a number of other things connect to this same line.

The only problem that I had adding anything to that line is that I ALWAYS had a fair amound come out the throttle body into the air intake hose.
This is the easiest place to add the seafoam....but I would add it to another location.
I have, carefully, used the vaccum line that goes to the Power Brake unit.

Did you do this while it was running? None should be able to escape the vacuum of the engine. Any vacuum hose should work but the trick is to suck most of the can in slowly before killing the engine. You do want it to sit in the cylinders to loosen the carbon build up. Also you dont want to pour it in to fast and get it in too much of a liquid form because liquids dont compress. 30 years ago we used to use automatic transmission fluid because it was High detergent but I believe Seafoam works much better.

[Zanel]

Thank you all for good advices.
As per DRW1000, I have checked EGR Vacuum by applying a vacuum at upper EGR valve port, the engine stalled immediately, thus it is OK.

I have not done any carbon built-ups cleaning yet, but planning on doing so early next week.

Regarding vacuum intake port location: I have two, one on left-end side of lower intake manifold (a hose attached w/bolt) and second on right-top of upper intake manifold plenum next to throttle body.
Which one would be the best to put Seafoam in?
Thank you.
Zane
--

[Zanel]

Thank you all again for good advices.
I have passed the emission tests, NOx is now back to normal as everything else.
My assumption is that it was dirty EGR ports.
--
Zane
--

[meta_nerd]

Which port did you put the seafoam into? I have the same problem and am very nervous, as the last car I worked on was my 72 chevelle, years ago. So any help would be appriciated with these cars that make me shreek at even sparkplug replacement.

thanks

[wiswind]

Meta,
Your profile says you have a '96 windstar.
I also have a '96 windstar (3.8L engine).
I have been learning as I go.....as I have started doing much of my own car work over the past year.
I have a subscription to www.alldatadiy.com
I have also used the free repair guide at www.autozone.com

I find it best to have a picture of what I am getting into before I start a project.
As I tackle a new project....I take pictures along the way...and post them at http://community.webshots.com/album/201931518cScpNK

For cleaning the parts of the intake that the fuel gets to.... I use Redline Complete Fuel System Cleaner. 1 bottle will treat the tank of gasoline.
I also use this product in a "maintenance" dose....the bottle has markings on the side that indicate how much to add for each 10 gallons of fuel. This product has a lubricant in it that will help the fuel injectors and valves in the engine.
Another very highly rated fuel system cleaner is Chevron Techron. I put 2 "treats up to 10 gallons" bottles into each tank of fuel.

If your EGR ports in the lower intake manifold have never been cleaned.....they most likely are due.
They are cleaned by removing the upper intake manifold. I do not think that one would be successul in cleaning the EGR ports by using Seafoam or a fuel system cleaner.....
The Seafoam cleaning that is mentioned here is for cleaning carbon deposits from inside the engine....as in valves, pistons, and head. The seafoam will also help to clean the IMR (Intake Manifold Runner), and the other parts of the intake.
The easiest place to add the Seafoam...or other product is through the PCV valve port.....but...as I mentioned....I had some run out the throttle body into the flexible hose that goes to the air filter.....so you would want to remove the hose from the throttle body....and wipe things up when you are finished. That is also a good time to see how clean the throttle body plate is.

Spark plugs....I would take the trouble to get ONLY Motorcraft Double Platinum spark plugs.
You can do a search on spark plugs in this room....and find a lot of discussion on them. I change the rear plugs by driving the front end up on ramps.....let the engine cool......and remove the rear plugs from under the car.

[meta_nerd]

wiswind,
I have read through many of the posts you have helped on and would like to thank you for all of your thourough posts. (Actually everyones are very helpfull, but yours have been very very helpfull to me) ;?)

Here is where I stand right now.
Trying to get this 96 windstar (3.8L engine)(125K miles) to pass smog (CA).
Replaced the Mass Air Flow already.

========================
OBDII:
misfire status = complete
fuel status = complete
comprehensive status = complete
catalyst status = complete
heated catalyst status = not available
evaporative status = not available
secondary air status = not available
ac status = not available
oxygen status = complete
oxygen heater status = complete
egr status = complete

DTC reported:
P0171 = system to lean (bank 1)
P0174 = system to lean (bank 4)

MIL status:
the malfunction indicator lamp is commanded on.
============================

Here are my symptoms:
Idles very rough when comming to a stop (and just after).
If exiting an inclined offramp the car will usually stall upon complete stop (i often give it a bit of gas to keep it from stalling but don't know if it is helping)
once it sits for about 10-20 sec, it idles better but seems to have a beat like a bad sparkplug/sp.wire. (I changed the front plugs and will finish changing the rear tomorrow). All the vacuum lines seem to work, the EGR vacuum is weaker than the others at idle, but I believe this is ok. I did hook a vacuum up to it and got it to stall the engine by applying suction, so hopefully that means the valve is working. It also seems that if I turn the wheels almost untill power-stering limit the idle drops very briefly for a moment (not sure if this is related). Luckily I picked up an OBD connector so I can play with this tomorrow at home. Please let me know anything that might help. The front 3 sparkplugs were in great shape, I will post my findings tomorrow on the back 3. Thanks for the quick reply... this site so helpful.

Also If I take off the upper intake, do I have to replace any gaskets?

Chris