1992 300D 2.5 EDS error 5 drama - PeachParts Mercedes-Benz Forum

pdrayton · #1 08-04-2008, 02:51 PM

This car went swimming up the engine firewall in a retention pond. Everything is working fine except the wipers and cigar lighter at the moment. Yes, I did a compression check and all cylinders are between 22 and 24 bar, which is in specification (big sigh of relief on that one)

And of course, EDS code 5 - y31/1 vacuum transducer for the EGR activator. It just won't go away, even though I put in a new vac transducer.

I think part of the problem is that I don't understand how the transducer (I'll call it VT for short) works. Does it respond to the electrical signal from the EDS and thereby decide how much vacuum to let through to the EGR?

And there's that switchover valve after the VT. What does it do? DOes it switche the vacuum on and off to the EGR depending on whether it is getting 12v from the EDS (ie OK signal)?

Since the error 5 (Y31/1 exhaust control loop vacuum transducer) wasn't fixed by putting a new transducer in, I'm thinking it could be the switchover valve that the transducer passes the vacuum too. But I haven't figured out how to test it from the FSM. Any advice? How should it behave when vacuum or voltage is applied?

And how do I test the EDS is OK? Where is it, so I can tell if it might have got wet for a start.

The reason I am trying to fix this is that the car has a rough idle and smokes when cold. When it's warmed up a little it runs like a dream. A TSB I read said these symptoms are from a bad VT. But replacing it didn't help the issue. I think the issue is electrically related to the EDS becuase when the car first starts it is fine for about 4 seconds and then starts shaking and missing.

Any ideas?

I wish there was a write up on how the EDS and EGR works. I've read a lot of posts on the forum about this error code, but nothing that helps me so far. Seems they made the 91/92/93 cars differently.

compress ignite · #2 08-04-2008, 04:32 PM

Details here:
http://www.peachparts.com/shopforum/showthread.php?t=212097

And BC's EGR blocking kit.

Then remove all that crap for the EGR/Flap, Vacuum actuators/electric sensors,
tubing ,Etc.,Etc. FOR TESTING PURPOSES ONLY!

The only functions the EDS will then provide are idle control and Clima assist.
Which are run by a part of the EDS that could care less about EGR/Flap.
AND you'll never be a slave to No Boost again!

compress ignite · #3 08-04-2008, 04:35 PM

#2

The last two pictures are the wonderful end result:
1.The EDS is now your servant...instead of a slavemaster.
2.Much cleaner more orderly engine compartment.

oldiesel · #4 08-04-2008, 04:42 PM

Paul
Sorry to hear about your cars dunking,glad your wife is OK! why dont you get rid of all that stuff along the right side of your engine compartment and simplify your life.I did mine and GSXR and a couple of others have done so.Simply replacing the wastegate actuator with a pressure operated one and you can rid yourself of all that complication and expense.That also allows you to get rid of all the EGR junk (for off road use of course) and you will no longer have the exhaust soot mixing with the oil vapors from your crankcase breather and gunking up your intake manifold and valves.Do a search and you will find an extensive write up on this mod with pictures by GSXR. My $.02 Don
OOPs looks like CI types alot faster than i!

pdrayton · #5 08-04-2008, 05:49 PM

I'm definately confused now. All the posts I read said the 602.962 you couldn't remove the EGR transducer becuase then the EDS freaks out.

If I'm reading you correctly, you're saying remove the (EDIT

connections from the EDS to the wastegate system so that even though it is freaking out, it doesn't have any connection to the wastegate, so it doesn't matter. Is that right? Same for the EGR.

If so, that sounds like a good idea for my future. However, I have turbo boost - more than 10psi (crappy gauge stops at 10psi) so the turbo is working.

The only problem I really have is the rough idle at start, and smoking. I figured it would be easier for me at the moment to isolate the problem by blocking the vacuum line from going to the EGR vac transducer, then it won't activate the EGR (is EGR german for 'stupid idea'?)

Part of my confusion is that I'm not sure where the waste gate activator is. Is it attached to the bottom of the turbo (called the Boost Pressure Control Vacuum Unit in the FSM), or is it the thing on the other side of the cross over pipe, opposite the EGR valve? What is that thing for anyway, opposite the EGR? And while we're talking about it, I don't remember ever hearing a good reason for recycling the exhaust gases.....

AS I understand how the turbo works is that the vacuum going to it (after the switches and vac transducer) determines how much boost it pushes into the crossover tube. Is that all that all that crapoola is for? Seems out of hand. And the EGR just adds soot directly from the exhaust, so it doesn't have anything to do with the turbo. The butterfly thing (called part 100 Vacuum control flap) opposite the EGR does what?

Sorry for the rambling post... to recap..

1. Is the wastegate at the bottom of the turbo?

2. What is the thing opposite the EGR on the crossover pipe?

Thanks!

pdrayton · #6 08-04-2008, 08:44 PM

OK, I''m less confused. I read the whole GSXR wastegate replacement thread and it seems like a GREAT idea. Can't wait to get rid of the rat's nest of tubes and $120 actuators! Sheesh!

It does make me wonder why the Merc engineers put it in if there was such a simpler way to do it....

I also now know the wastegate is on the turbo and the vacuum control valve (opposite the EGR) is affectionately known as the 'flapper' valve. A reference to Douglas Adams perhaps?

pdrayton · #7 08-04-2008, 08:47 PM

CI's post that the EDS control idle speed, makes me wonder if it is the cause of the rough idle and smoking when cold? I don't see how it could make the car smoke though.....just thinking aloud, it's really bugging me. Could be something as simple as the biodiesel is not completely converted and it's the uncoverted vege oil that is causing the smoking. Or the indian injector nozzle.....

pmari · #8 08-04-2008, 09:14 PM

Sorry to hear about your mishap, hope all humans were unharmed. I'm at work right now so I'll have to give a quick response and try later to help.
The EDS is behind the battery (behind the plastic flap) it is a rectangular bbox approx. 1/2-1" thick X 6"x4" attached to many little wires that make up a big cable. I know it's vaugue but you see it, if not I'll snap some pics. I would go to radio shack (or any electronics store) and pick up some "Deox it"
and go through all your connections (including the EDS) I would also suggest you get some dielectric grease and apply it liberally after you Deox.
advance search under BigBen, bobodaclown, 2.5Turbo, dieselbeagle and me using terms like boost, eds, transducer.
I'll catch up around midnight

http://www.peachparts.com/shopforum/attachment.php?attachmentid=42751&d=1175279556

http://www.peachparts.com/shopforum/showpost.php?p=1816125&postcount=7

ELECTRONIC DIESEL SYSTEM (EDS)
Model Model Year
124.128 1990-93
126.134 126.135 1990-91
140.134 1992-93
FAULT CODE TABLE
DTC Readout Possible Cause of Failure
1 No fault found
2 Fuel rack position sensor (L7)
3 Air flow sensor signal (B2/1)
4 Electronic diesel system (EDS) control unit (N39) or atmospheric pressure sensor
5 Exhaust gas recirculation (EGR) valve vacuum transducer (Y31/1) or fault in exhaust gas recirculation
(EGR) control circuit
6 Electronic diesel system (EDS) control unit (N39), internal voltage supply
7 Starter ring gear speed sensor (L3)
8 Engine coolant temperature sensor (B11/4)
9 Intake air temperature sensor (B2/1a)
10 Voltage supply insufficient
11 Electronic idle speed control actuator (Y22) or exhaust gas recirculation (EGR) valve vacuum transducer
(Y31/1) or Boost pressure cut-out switchover valve
12 Not used
13 Electronic diesel system control unit (N39), faulty (internal fault memory)
14 Electronic diesel system pressure sensor (B5/1), defective
15 Boost pressure control/ pressure control flap vacuum transducer (Y31/5) , or defect in Boost pressure
control circuit.
Or
Intake manifold air pressure control valve vacuum transducer (Y31/2), wastage vacuum transducer
(Y31/3), or malfunction Intake manifold air pressure circuit

As of February 1992, a modified vacuum transducer has entered production. The new part can be identified by a black ring, however, the part number remains unchanged. In case of customer complaints of engine surging at approximately 50-60 MPH, smoking rough idle after start, or poor power output on vehicles with earlier production dates, the tests in this bulletin should be performed; see Testing.
Pressure control flap test (engine 602 only)
1. Connect vacuum tester to vacuum actuator (arrow, Figure 1).
2. Apply vacuum slowly until lever (a) contacts stop (b).
3. Vacuum reading should be 385 +/- 5 mbar. If necessary, adjust by loosing screws (c) and sliding vacuum actuator (100) in the slots. Release vacuum and repeat test if needed.

Vacuum pump test
1. Connect vacuum tester (019) to accessory connector on vacuum pump (arrow, Figure 2).
2. Disconnect main vacuum hose (B) from brake booster (A) and plug.
3. With engine idling, reading should be 700 mbar after 30 seconds. See barometric (altitude) correction table in this bulletin.

Barometric (altitude) correction (see chart)

Readings must be adjusted according to the prevailing barometric pressure to compensate for differences in altitude (deviation from sea level). When performing the vacuum pump test, reduce the reading obtained according to the altitude dependent value in the chart.

Vacuum system and consumer test

1. Using a Y-connector, connect vacuum tester into consumer connector on vacuum pump.

2. With engine idling, check that reading is at least 600 +/- 30 mbar.

3. If vacuum is below 570 mbar, check the following for leakage: line to vacuum control valve (65) (transparent), line to consumers (grey), vacuum transducers (Y31/1 and Y31/5), as well as the black/white vacuum supply line. To check, disconnect and plug lines at T-connector or double T-connector (arrow, Figures 7, 8, 9, and 10) one by one.
4. If vacuum is greater than 650 mbar, check for possible leakage in the vacuum line system.

Vacuum transducer test (Y31/1, Y31/2, Y31/3, Y31/4, and Y31/5)

1. Using a Y-connector, connect vacuum tester to consumer connector on vacuum pump.

2. With engine idling, disconnect connector VAC from transducer Y31/1 and plug line. If vacuum reading is below 650 mbar, replace vacuum transducer Y31/1. Repeat procedure for vacuum transducer Y31/3 (124.128 model year 1990-91) and Y31/4 (140.134)

3. On engine 602 only, with engine idling, disconnect connecting line VAC from transducer Y31/2 (model year 1990/91) or Y31/5 (starting model year 1992) at the Y-connector black/white line and plug. If vacuum reading is below 650 mbar, replace vacuum transducer Y31/2 or Y31/5.

Model years 1990/91
Engine 602.96 Model 124

Y31/1 EGR valve vacuum transducer
Y31/2 Pressure control flap vacuum transducer
Y31/3 Wastegate vacuum transducer

Model years 1990/91
Engine 603.970 Model 126

Y31/1 EGR valve vacuum transducer

Starting model year 1992
Engine 602.96 Model 124

Y27 EGR switchover valve
Y27/4 Boost pressure control switchover valve
Y27/5 Pressure control flap switchover valve
Y31/1 EGR valve vacuum transducer
Y31/5 Boost pressure control/pressure control flap vacuum
transducer (not visible, located under air cleaner housing.

Quick trouble shoot....
From DanG ChicagoArea
====================
I've decided to go into great detail of what I did to the 2.5. The white
2.5 had a blown head gasket when I got the car. It contaminated a number of
vacuum items, which is why I started bypassing stuff.

1) Overboost protection canister. Small one on the driver's side firewall.
Had soot in it, and prevented the ALDA from sensing pressure. Bypassed. I
don't think that I've had ONE of these work correctly on any turbo. They
all get sooted up eventually.

2) EGR. Also full of soot. I have a good replacement, but haven't gotten
around to replacing it. An EGR on a diesel is a dumb idea anyways because
feeding soot back into the intake is not good for it. Bypass is easy. Keep
the electrical connections intact to the vacuum pod. The signal to open and
close will be there, and the computer will be happy. Disconnecting the
vacuum lines and bypassing is all that needs to be done.

3) Turbo wastegate vacuum pod. The wastegate has a vacuum failsafe that is
normally open with zero vacuum. Bypass is to connect the wastegate vacuum
(which is the electrical/vacuum pod closest to the passenger side headlight,
low in the inner front fender), and hook it directly to the main vacuum
system. My wastegate vacuum pod leaks, and I need to replace it. Bypassing
is only temporary, as that particular failsafe is not good to ignore for too
long. The key to preserving the computer happiness is not disconnecting the
electrical harness to the vacuum pod.

4) Secondary turbo fault sensor. If something is very flaked up with the
computer or sensors, the secondary sensor which is mounted by the battery,
opens to kill boost pressure to the ALDA. Bypass is easy for troubleshootin
g. The only reason why you would want to bypass this for any reason is to
find other faults.

My point is that the highly sophisticated computer controlled turbo system
can be made very simple. Call it emergency road repair 101. If you have a
full time vacuum direct connect to the turbo wastegate, you'll have turbo.
If you have a single pressure line from the intake manifold to the ALDA,
you'll have appropriate fuel enrichment. Leaving electrical items attached
to the vacuum pods keeps the computer happy and compliant.

bobodaclown · #9 08-04-2008, 09:47 PM

Haven't been around in a bit. Life happens. In the process of becoming foster parents. (WOW its a lot of work)... I'm a bit confused... Your throwing a code 5 and still getting boost??? Usually if you've got a problem you'll loose boost. Check carefully the tubing routing. I mean really carefully.

If your having idle problem is it low? High? you can adjust the jumper to set the idle.

they recycle the exhaust gases to keep NOx down. less air doesn't burn as hot less NOx. (nut shell readers digest version)

pdrayton · #10 08-04-2008, 10:06 PM

Thanks Guys.

Pmari - I ran through those tests, but they don't make sense - it says to disconnect the vac connector to the unit and then see how much vacuum it has. That doesn't make sense. Disconnect it and then see if it has vacuum?

Anyway, I'm headed for removing all that crap with a pressure activated actuator.

BOBO - the turbo is now not working again. I'm not sure what is going on. It's starting to get to the point where I just want to rip that stuff out and stomp on it. Maybe throw a little gasoline on it....

bobodaclown · #11 08-05-2008, 10:15 PM

Did you try by passing all the stuff to ensure the turbo is working. Code 5 isn't stored. Pulse counter will only display at 900 RPM for at least 5 seconds. Fault is not stored.

Supply line leaking... Vent line clogged.... Vent filter clogged Air flow sensor... EGR valve.... Coolant temp sensor......

Wish I was closer... I love a challenge.

compress ignite · #12 08-06-2008, 01:08 AM

WAG (Wild *** Guess)

More than it's deserved portion of that nasty black sooty EGR input at idle with
a cold engine? [I'd choke, shake and smoke,too.]

pdrayton · #13 08-06-2008, 07:24 AM

Bobo - I'm not sure what you mean by "Pulse counter will only display at 900 RPM for at least 5 seconds" or what that implies regarding the error.

Yes, the turbo works fine when the Y35/1 and switchover are bypassed - gets over 10psi .I bought a new boost gauge that goes over 10psi to check it out. Will do today.

Supply line get's over 20 mmHG when isolated. Y31/1 is leaking. If I plug the supply line to it, will that upset the EDS? And just to be clear, when the EDS senses an EGR fault, does it cut the boost?

That could be what is happening - EGR transducer is leaking (the old one) and it cuts the boost. I've done so many different tests on it, I'm getting confused on what the situation is. I'll put the new transducer on and see if the turbo works again. Then I know it is EGR trans. BUt I don't want to put the new transducer in ($120) since I'm going to remove it all as soon as I can find the supplier for the pressure actuated wastegate controller....

CI, yes, perhaps it is the recycled EGs that are causing the smoking. I'll pull of the EGR valve and see if it can be cleaned to not leak.

pdrayton · #14 08-07-2008, 07:55 AM

Update: Boost goes up to 12 PSI then drops to zero and stays there after the car is first run. That's with the old leaky Y31/1 EGR transducer. WIth a brand new transducer, the boost goes to 12psi a couple of times, and then drops to zero and stays there.

So clearly the EDS is seeing some problem and shutting things down. However, since the boost goes up once and then drops off, I'm starting to wonder if it is the airflow sensor or something like that killing the boost.

The EGR and flapper valve removal and replacement with a pressure activated boost controller has me worried on this point. I've read that the EDS watches the MAF to tell that the EGR is working and if it doesn't sense less air flowing when the EGR is enabled then it cuts boost as it figures there's a problem.

I think I answered my own problem there - it's not going to make a difference with the pressure actuator becuase the turbo can't be cut off by the EDS when it has the pressure actuator.

Anyway, I'm thinking I should test the airflow sensor, whatcha think? Maybe it is screwed and not registering the change in airflow. But, now that you mention it, I don't really care becuase I'm going to replace all that crapoola anyway, if I could just find a pressure actuator....

My turbo is fine - shot up to 19 psi when I tested it without the transducers in the way. ALmost pooped my pants when it did that, was scared I was going to fry a piston!

compress ignite · #15 08-07-2008, 05:13 PM

Y30 "Sees" overboost at 138 and makes 103 limit fuel delivery.

EDIT:
I know I beat this horse, every time it comes up.

I checked with the Bosch Service Station Locally about our systems and
OverBoost (as in your pressure waste-gate actuator fails to open at 14PSI)
IF your Overboost protection (On the Fuel side) is functioning all that will
happen is additional air in the combustion process(and no harm done).
IF the orifice in 138 is clogged by EGR soot/oil mist combination
Y30 (the engine overload protection,switchover valve)
WILL NOT GET THE OVERBOOST PRESSURE and the turbo can spool up to the point of slinging blades.
This is an excellent reason to KEEP the intake tract clean.

[YES, That's the beauty of the GSXR "Improvement" all that 15+ year old
electro/vacuum foolishness bothers you, Nevermore.]