W124 93 300D 2.5 Boost Problems (I too am stumped!) - PeachParts Mercedes-Benz Forum

James L · #1 04-27-2007, 12:27 AM

I am stumped!!!! I have read through all the searches on EDS boost problems, flap control, vacuum transducers, ect...; BigBen, 2.5Turbo, DieselDummy, Denrac, gsxr and pmctechnie. I also have the service cd and have read through the 07.1 1120 troubleshooting (well written but complicated!) I also did the homemade radio shack LED pulse reader (works great!) The fault codes are; 3-air flow sensor B2/1, 5-vacuum transducer Y31/1, 8-coolant temp sensor B11/45 and 15-charge pressure control/vacuum flap transducer Y31/5, I then cleared the fault codes, still same symtoms. Now disconnecting battery overnight to see if this will reset the EDS.

Background; while changing the air filter I cleaned all the vacuum lines, intake nipples leading to the ALDA with shop air and a little brake cleaner. Also changed both fuel filters.

Symptoms after; real slow 0-60, real slow turbo kick in, a/c does not blow out of center vents, transmission shifts wierd.

I checked all vacuum lines and electrical fittings and all are connected. Using my mity vac hand pump, I sucked at all the tees and fittings, when I vacuumed at the tee (Y) fitting above the air filter behind passenger headlight (black/white vacuum line going back to engine and the other line going down to the Y31/5 EVERYTHING works, strong center vent a/c, boost, turbo, shifts ect. but it goes back after I turn off the engine or a/c.

To check voltage, the manual talks about an N39 coupling plug? next to the battery to connect a contact box and test cable? for use with a multimeter.

The only thing left to try is to take apart every line and blow through and clean again for blockage. To further troubleshoot, the service cd talks about this N39 plug to check voltage/ohms but I do not have this coupling/contact box, anyway around this tool?

Any help is appreciated.

compress ignite · #2 04-27-2007, 12:55 AM

The only thing you might have done (wrong) was to leave a little brake parts
cleaner in the system.[it evaporates so quickly...I would not be concerned]
[unless you "hosed" the MAF sensor down]

Almost all the symptoms are vacuum/sensor related...take your time ...
somewhere there is a small leak (or bumped disconnection).Or dirt clump.
Eye all the reconnected "Electrics" as well.

Remember all this stuff has lain undisturbed for 14 years since the car left
Sindelfingen...and along you come with the best of intentions to clean up.
Just touching some of these ancient rubber connections/hoses/diverters is
sometimes enough to cause a gap.

A hiccup in the ambient air pressure (barometric) if allowed into the system
will have you "chasing demons" for a while.
Say "BOO" to the EDS and it'll find a way to cramp your style.

I believe the reference to the voltage/amperage check is the diagnostic port
(just in front of the battery)...There may be a way to check with a DMM
without all the factory folderol. Do a search for EDS VOLTAGE.

Under no question is stupid...triple check your vacuum hose(s) reconnects.

pdrayton · #3 04-27-2007, 08:19 AM

I had eds 5 code for a long time, learned a lot about the document you mentioned, especially after reading it the 26th time. What l suggest is:

1. Determine if this is the components or the EDS that has a problem. To do this, check each component individually (the ones it says are broken). Find one you know is good and functioning. If it is working and the EDS says it isn't, to me that means the EDS has an issue.

I would start with the coolant sensor - it reads a certain amount of ohms depending on the temperature of the coolant - something like 350 -600 for 85C coolant down to around 100 for 30C coolant. If it reads the right ohms and it is getting voltage, then I would say your EDS or something along those lines is funky.

To check the vac transducers, you can put vacuum on it with 0 V across the electrical connectors and see where the vacuum comes out. THen apply 12V (low current, use a small 9V battery, it works fine) and the vacuum should come out the other port (dump or through). If that works, block off both dump and through outlets and apply vacuum to the in port. If it loses the vacuum, then it is faulty. That's what mine was doing.

2. I forgot what 2 was, but I do have a question. Was everything working fine before? And it stopped working after you changed the air filter etc? Then the dumb question is, you did reconnect the air flow sensor on the air intake housing right?

In case the ALDA got damaged somehow, try bypassing it. I'm not an expert on that, but I think you can just take it out the loop and plug it up - check the forum though, there a lots of posts on it, and disabling the EGR too (which uses the Vac transducer by the coolant tank. At least that will eliminate those two, if you have no other options.

2.5Turbo · #4 04-27-2007, 11:45 AM

I too would check the transducers just to be sure. If I remember correctly this car has two, with a couple switchover valves for the EGR and such. Try swapping the transducers (they're the same part number) and see if your situation improves. Be sure to clear all codes after the swap. I swapped my wastegate transducer with the intake flap transducer (the 90-91 300D has 3 transducers) and the boost came back, at least until the EDS found out about the non functioning intake flap...narrowing down the problem to a faulty transducer.

Also, be sure that you're clearing the codes properly. Each must be cleared one at a time as they are read...for example after each 2-second button press and code readout, hold down the button for 8-10 seconds to clear that code only.

The ACC and transmission problems narrows it down to a vacuum problem, because as you probably know, those two devices are dependant upon vacuum for correct operation. When you say the transmission shifts "weird," do you mean it shifts hard? If so, vacuum is definately not getting somewhere.

2.5Turbo · #5 04-27-2007, 11:50 AM

Quote:

Originally Posted by pdrayton

2. I forgot what 2 was, but I do have a question. Was everything working fine before? And it stopped working after you changed the air filter etc? Then the dumb question is, you did reconnect the air flow sensor on the air intake housing right?

Ha, I did that exact thing when I was trying to fix my no boost problem a couple months ago! I had to take the airbox out to access the wastegate transducer. When I replaced it I didn't reconnect the plug, and when taking that test drive of truth, you could say one could hear a few expletives from the driver's seat

James L · #6 04-28-2007, 02:39 AM

Thanks for replys, some good thoughts. I worked on the car all afternoon with shop air, brake cleaner and mighty vac. flushed back and forth between junctions carefull not to blow into any components (I fear this is were my problem came from, my wife says I screwed it up she is looking faith in my skills!! LOL.) Took air filter assembly off to fully access the transducer.

When I pull mity vac on flap control the valve moves full swing. A few seconds after I shut the engine off I can hear it flap closed.

Also took coathanger wire and fished into the intake plug that hooks up to the alda. alot of crud came out. Also replaced any old looking rubber vacuum line fittings for fun.

Anyway after all this re-read the LED pulse counter with engine on, a/c off. now just have the 5-fault code (cleared) same as above but not the 3, 8, 15
.
Car does the same thing, same symptoms. Next I will try the vacuum transducer (anyway to test with mity vac?) and electrical valve it connects to for voltage.

Thanks and keep the EDS suggestions coming.

pdrayton · #7 04-28-2007, 09:34 AM

For me, the 5 EDS code was the EGR vac trans. It's the one next to the water coolant tank. I described how to test it in my previous post - put vacuum at the in, see where it comes out. Then put 12V across it and apply vacuum. The vacuum should then come out the other port. Also, close the two out ports and put vacuum across it and check that it holds vacuum. If not, it's buggered.

Like I said before, you can try disabling the egr - I'm not sure how, but there are posts on it. The EGR not working seems to switch off the turbo. I don't see why, but it does (or at least, it did for me and fixing it fixed the turbo issue).

BigBen · #8 04-28-2007, 11:10 AM

James L,

I'll repost here a method for testing which has been very useful to me (I took it here but don't recall who posted it initially).

From my experience on my 1992, I would suggest to go this way:

1. Make sure you have 700mbar of vacuum from the vacuum pump. Disconnect brake booster vacuum line and plug the port on the vacuum line to eliminate any vacuum leak through the brake booster.
2. Apply vacuum to the Intake Flap and make sure you can get full swing of the flap. See the procedure below. It is important that it is correctly adjusted to fully closed position with 385mbar vacuum. If not, EDS will open Wastegate resulting in no boost... I have removed my charge air cross over pipe to actually see the flap close properly. It is critical this occurs correctly in order for the EDS to "see" the reduction in air flow when it needs to see it (usually under light loads, downhill, or higher idle).
3. Remove the EGR valve, clean it, and make sur it is properly working, thus allowing exhaust gases to flow back in the intake when the intake flap closes.
4. Test your Y31/1 and Y31/5 and if all seems ok, do a swap between the two as mentionned before by 2,5Turbo.
5. Disconnect the vacuum line to the Wastegate and connect a permanent vacuum straight from the vacuum pump (but then easy with your right foot and have a pressure gage hooked on the intake manifold). Pull back the throttle if it goes past 15-20psi!!!

Please report your boost readings, if available, that will help us a lot understand your problems.

Best of luck,

Bye, BigBen

PS. Here is the test procedure:
_____________________________________
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.
____________________________________________________

pmari · #9 04-28-2007, 12:41 PM

Model Model Year
124.128 1992-93
140.134 1992-93
Connect wires of Scanner as follows (124)
Scanner Data Link Connector 8-pin
Yellow Socket 4
Black Socket 1
Red Battery (+)
Connect wires of Scanner as follows (140)
Scanner Data Link Connector 38-pin
Yellow Socket 4
Black Socket 1
Red Socket 3
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 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.

pmari · #10 04-28-2007, 01:31 PM

Vac Lines

pdrayton · #11 04-28-2007, 04:56 PM

pmari- where did you get those pics of the turbo parts? I have the FSM but I haven't found that diagram, just cryptic references to Y31/1 etc and having to figure out what it is myself.

pmari · #12 04-28-2007, 07:03 PM

Either the russian site , ALLDATA or Mitchells CD's.
Big Ben did a nice one also. The Trouble shoot BB posted is from Alldata.

Compress & Ignite had a pertinent comment about all this rubber and wires sitting around under a hot engine bay for few years. IMO, One of the first things to do is to go around and clean/inspect /dielectric grease all the electrical connectors. Then inspect or routinely replace the vacuume lines.

Quote:

Originally Posted by pdrayton

pmari- where did you get those pics of the turbo parts? I have the FSM but I haven't found that diagram, just cryptic references to Y31/1 etc and having to figure out what it is myself.

James L · #13 04-29-2007, 02:17 AM

what type of pressure gauge tool do i need for the test stated above? andwere to obtain? i have a mity vac w/ gauge.

the posted fsm sheets above are in the engine combustion section 07.1 1120.

thanks everybody for the excellent advice for this complicated troubleshooting!

BigBen · #14 04-29-2007, 11:48 PM

James L,

A turbo gage that has the needle resting at 0 in the center position should read +20 to + 30psi pressure and -15 to -20psi vacuum. Such a gage is all you need. I have an Autometer gage, circular about 2" dia. that mounts into the dash.

1000mPa (or 100kPa) is nearly 15psi.

Bye

Wolfsburg · #15 04-30-2007, 09:11 AM

Does yours have a Cat convertor...mine does at least, (an 87 603)and it was clogged, and I had no power, max speed maybe 20 mph...to check remove the bolt at front of engine on the exhaust manifold, and see if you get a ton of black crap coming out. These engines need air and lots of it...For more info do a search under my name and no power...I also thought it was the end..and boy does my 603 move now..its great!!! Maybe this is your problem and it is often overlooked. Good Luck!