Well done.............

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A Dalton

Good detective work . . .

Alas the DTC#19 code, if it's real, and I've never seen a 'false' one, will come back. the "book" says it can be caused by a vacuum leak or bad injector or two but I've never seen any of the other failures types.

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Regards . . . . JimF
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'94 S500 Cpe

Visit my Mercedes Web Page

Don't over-look this part

http://catalog.peachparts.com/RenderScriptTemplate.epc?_cmd=epccat_VehicleAAA&cookieID=2GN17VPXQ2GZ0RP5EF&yearid=1994%40%401994&makeid=MB%40%40MB%40%40X&modelid=E%2D420%2D001%40%40E+420+Sedan&catid=C%40%40Fuel+Injection&mode=PA&subcatid=C3000@@Fuel+Pressure+Regulator&source=www.peachparts.com&clientid=catalog.mercedesshop

It is a common failure part with age that will directly influence trims if it is leaking internally...the test is to take the vac line off and look for evidence of petro..there should be none. If there is, what happens is that raw gas gets sucked into the intake as UNMETERED fuel and the ECU can not correct w/o getting out of it's window frame %. So, code 19.

Takes 2 seconds to check and happens all the time. The best test is to run the car with the vac hose off for a few secs, as that will put the highest pressure on this part and if it is faulty, you will see fuel coming out the vac port.
Alway check that on fuel trims that have high adaptations/% and codes.

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A Dalton

Thanks Arthur for the tip. I have checked the fuel pressure regulator as you mentioned. I pulled the vac line and let it idle for about 5 minutes and nothing came out. I turned off the engine and let it sit with the vac line off and still nothing.

This morning I cleared all the codes. It takes about 2 days for the CE light to come on. I will report back after 2 days or earlier if it comes on again. Thank you for all your help.

Very good..
Just thought I would mention that b/c I have seen it over-looked by so many
posters , only to later find that was the problem after they spent big $$$$ on everything else............
You prob just need to up the window % , but just don't want to do that if one just has a simple repair causing the adap to get out of line...........
The trick is ...is the adapt just basically normal for a used engine, or is the trim out of line b/c of a vac leak or a fuel pressure/injector, etc issue.
That chassis has a small % window, so it may well be it just needs some more leeway...that would be Jims upping the window % mod.
Later cars had a larger window to compenstae for more trims w/o a warning lamp or code, so that tells you something.
One other simple test I would do if the lamp comes back and related to FP is a FP test.
The FP is regulated by a diaphragm in that Regulator that is actualted by engine vac. So, a FP test consist of pressure with the vac line connected and with it disconnected. The higher reading is w/o vac line..the test is to see if the pressure DROPS in spec when the line is put back ON. If there is no difference , then the reg is bad and the excess to spec will cause the car to run rich, thereby bringing on a trim code .
So, look up the specs for your car on a FP chart. There will be 3 different specs to check:
1-FP w/o vac line attached [highest]
2- FP w/vac line attached [ lowest and working pressure].. this is the most important spec., as that is what the injectors see, and if too high, adaptations come into play.
3 - car OFF ---FP should HOLD for at least 30 MIN

These 3 test will tell all and are quite easy to do and should be done before any other test with your complaint.
If youy have a gauge and can not get the specs for that chassis , I will post them [ or archieves]

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A Dalton

I have the a gauge so I will perform the test but I don't have access to the specs. If you could post them I would be grateful.

On a side note the CE light came back on yesterday afternoon on a cold start and only code 19 appeared. I will have to wait a couple days to see if code 4 comes back.

In the mean time I will perform the FP test.

Thanks.

LH/119 Fuel Pressure

Engine @ idle:

With vac ....3.2-3.6 Bar
W/O vac.....3.7-4.2 Bar

Engine Off for 30 min...No less than 2.5 bar

1 Bar=14.5 PSI

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A Dalton

I have completed the FP test and here are the results.

Just ignition on and engine off and vac on I get 52 psi.
Engine on and vac on I get 46 psi.
Engine on and vac off I get 56 psi.
I let the car run with vac on for 30 seconds and shut the engine off. Right after I shut her off the FP falls to 40 psi and in about 20 seconds climbs to 52 psi.
After 30 minutes it is at 33 psi.

So looking at the spec everything is good except I don't know about the the values read after I shut her off.

Is that behavior normal?

Thanks.

Passed the test.............

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A Dalton

So I assume the only remedy is the chip mod from Jim. Is there anything else I should check before I order the chip? Thanks.

Vac leaks...........including purge valve and egr.

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A Dalton

I did check the vac lines for leak on both they are good. The change over valve for the egr I did not check as I don't know when it is activated.

When is the egr change over valve activated ie. when is there suppose to be vacuum down stream and vise versa?

I don't know anything about the purge valve. When it is suppose to be on or off or what ever it does. Any help with the above items will be appreciated. Thanks.

What I am saying is you can check hoses and stuff for vac leaks, but if a purge or egr valve leak, the leak is internal, so you do not see it..but the engine sure does,

So, they are hard to find and require a hand vac pump and gauge to really check. many times you can narrow it down by cappin each one and trying the car ..if the problem goes away, you may have found the culprit.
The real way is to get adaptation values and try and correct from there.

And again, with the small % window , the car may require that much adaptation and be normal. Even a bad/weak 02 sensor or clogged air filter can cause/require higher than normal adaptations in order to correct for the condition.
If you had the values and they were close, you probably need the extra % the mod would give you, but if the values are way high, the higher % mod is not going to solve the problem, but may just mask it.
A Fat guy can't climb thru a small window, but he can go thru a larger one...However, he is still too Fat .......
..and a normal guy can go thru the small window...
Not much of an anology, but you can see what I mean.
Does your car pop a code b/c of a fault , or is running and trimmed in as close to normal as possible, but just has too small an operating window %.
As said, the original was a borderline, small window that did not allow for a system that needed just a little more adaptation..that is where the mod comes in..[ and why Benz enlarged the window on later models] ..but don't think the mod changes the adaptations the car is requiring to run corrected..it does not..it simply does not trigger a CE at the higher adaptation % b/c the window is now larger and that means the CE does not pop b/c the adaptations are no longer higher than the new , larger window..ie, you got a bigger window now that allows for higher adaptation w/o CE warning...

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A Dalton

That is a good question. I don't know how to read the values to see if I have a small window. All I have right now is a CE light which only returns code 19. How do I read the values? Thanks.

You don't see if you have a small window..you already know you do..that is what the modification does ..it give you a bigger window.., so the car can have a larger adaptation % without popping the CE and a code.

..but you need scanner equipment to get adaptation values...which is why we had you look for vac leaks and fuel pressure , etc ..hoping you would find something , as those few suggestions are common to effecting adaptation values. But you do not know those values and there is no way except with the equipment..
That is where it stands.

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A Dalton