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1991 500SL
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58 Posts
Discussion Starter #1 (Edited)
Car model, S500, 1992 W140 119 engine
The car was in Limp Home Mode. After reading pcmaker web site, found out the insulation of wiring harness to the throttle actuator and to the injector were gone. Replace wiring harness to the injector and re-wiring the throttle wiring harness. Put all back together the car run realy smooth. After using it for a month or so... the engine start real rough and into LHM. The RPM jumping up and down. Also black smoke coming out from the exhaust. Spray the Air Mass Sensor... no difference.
Thinking of checking the vacuum line, but don't know where to start and how many are there. I have subscribe to ALL DATA through pcmaker web-site and this should help to locate where the components are if needed.
Appreciate the forum help as the car was not running for two weeks now trying to figure out as well as reading a number of thread from this forum.
 

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1995 S600 Coupe * SOLD
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59 Posts
Just a thought but I had lots of wires on my s600 replaced, they were touching each other, and the insulation was almost gone. Check more wires, cut away the shielding and look for more degraded wires, then once those issues are solved check the computer modules and anything that was connected to the jacked up wires

Now I find that my mass airflow wires are jacked up, couldnt tell unless I cut into the black protection and took a look.

Nightmare with the wire harness situation.

Seems that whatever wire were closes to the engine are the ones that got degraded with the heat
 

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1991 500SL
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58 Posts
Discussion Starter #3
Thank you i will check the rest of the wire. What do you mean by "wires are jacked up"?
 

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1991 500SL
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Discussion Starter #4
Have check all wires and they are in good order. The exhaust fume is really black, and leave quite a bit of carbon on the floor. Errr....Vacuum line maybe?? Anyone?? CPS??? How do i check these parts if they are working ok. I have read a lot of thread....it might be fuel pressure regulator which located un the fuel rail. Or maybe EGR valve... How do i check to make sure these components are working properly. Appreciate all the help from this forum. Thanks everyone.
 

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1997 S600 (sold)
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4,660 Posts
Seria said:
Have check all wires and they are in good order. The exhaust fume is really black, and leave quite a bit of carbon on the floor. Errr....Vacuum line maybe?? Anyone?? CPS??? How do i check these parts if they are working ok. I have read a lot of thread....it might be fuel pressure regulator which located un the fuel rail. Or maybe EGR valve... How do i check to make sure these components are working properly. Appreciate all the help from this forum. Thanks everyone.
Black soot out of the exhaust would indicate that the car is running rich. Hunting idle probably supports this. Some basic things that may cause a rich running condition: fuel pressure too high (bad fuel pressure regulator), fuel injector(s) leaking, bad air mass meter giving false reading of higher air flow to the computer, (possibly also bad O2 sensors).

Fuel pressure is checked by hooking up a fuel pressure gauge to the fuel line. This is probably the easiest to check for the home mechanic. With the proper diagnostic equipment and factory specifications for the air mass meter readings, you could check the air mass meter output while the car is running to see if it is giving the correct values. Leaky injector... I don't know. May require bench testing the injectors.



Brett
 

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the obvious place to start is: Have you gotten a full diagnostic done on the computer to see if you have any stored codes? Don't throw parts and money at a problem if you're just guessing.
 

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1991 500SL
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Discussion Starter #7 (Edited)
Brett San Diego said:
Black soot out of the exhaust would indicate that the car is running rich. Hunting idle probably supports this. Some basic things that may cause a rich running condition: fuel pressure too high (bad fuel pressure regulator), fuel injector(s) leaking, bad air mass meter giving false reading of higher air flow to the computer, (possibly also bad O2 sensors).
Yes the engine has erratic idle. The RPM needle jumping up and down and the car is totally undrivable. How do i check the fuel pressure regulator?

Brett San Diego said:
Fuel pressure is checked by hooking up a fuel pressure gauge to the fuel line. This is probably the easiest to check for the home mechanic. With the proper diagnostic equipment and factory specifications for the air mass meter readings, you could check the air mass meter output while the car is running to see if it is giving the correct values. Leaky injector... I don't know. May require bench testing the injectors.
Brett
Where do i hook up the fuel pressure gauge? Is that at the incoming fuel line? What sort of pressure should i be looking at? I presume a sophisticated diagnostic machine is needed for checking the air mass meter output while the car is running to see if it is giving the correct values.
 

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1991 500SL
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58 Posts
Discussion Starter #8
FrankiE55 said:
the obvious place to start is: Have you gotten a full diagnostic done on the computer to see if you have any stored codes? Don't throw parts and money at a problem if you're just guessing.
I have a Trisco Palm Scanner (PS-411-BENZ). Will this be good enough for the job.
 

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1991 500SL
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Discussion Starter #9
Have dismantle the fuel pressure regulator, but don't know how to test if it is working ok? Check all vacuum hoses again and all are ok. EGR valve.... put vacuum and can hear click with no leak. I remember the air injection pump engage every time when i start it in the morning. Now the clutch of air injection pump did not engage when i first start the car. How does the air injection pump work. Does it have to switch on everytime in the early morning?
Appreciate all the help. Thanks.
 

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Seria said:
I have a Trisco Palm Scanner (PS-411-BENZ). Will this be good enough for the job.
Easily, if you know how to use it. If not you could build a flash code reader and pull the codes yourself that way. Your next step should be to read the codes in one way or another.
 

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1997 S600 (sold)
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4,660 Posts
Seria said:
Have dismantle the fuel pressure regulator, but don't know how to test if it is working ok? Check all vacuum hoses again and all are ok. EGR valve.... put vacuum and can hear click with no leak. I remember the air injection pump engage every time when i start it in the morning. Now the clutch of air injection pump did not engage when i first start the car. How does the air injection pump work. Does it have to switch on everytime in the early morning?
Appreciate all the help. Thanks.
Fuel pressures are tested with everything hooked up and working. I can only speak generally since I'm not familiar with the M119. Typically, there is a fitting that is for the purpose of hooking up a fuel pressure gauge. You hook up the gauge, run the fuel pump, and read the pressure. To run the fuel pump, you may have to jumper a relay or just turn on the key without starting the car. I don't know the factory specification for fuel pressure. You'd have to get all the more specific info from someone or somewhere else. To test the regulator out of the car, you'd have to have a bench testing system built with a fuel pump and mocked up fuel lines.

The secondary air injection should work on all cold starts.

I would suggest trying MercedesShop - Mercedes Benz Parts and Technical Information for more help.

Brett
 

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1991 500SL
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58 Posts
Discussion Starter #12 (Edited)
Hi guys i think i have big problems.
Here is the scan results from the hand held scanner.

LH, HFM, ME(R)
Read DTC - system normal
Read store DTC, two codes appear. 05 and 10.
Code 05 says Intake air temp sensor shorted or open CKT.
Code 10 says O2S 1 signal, shorted or open circuit.

LH,ME(left) - No ECU control or no data.

ETC system - No data from vehicle

DM system - No data from vehicle

EDS system
two code, 10 and 13
Code 10 says No description.
Code 13 says Elec. Diesel sys. ctrl unit faulty (internal fault memory)

BM system - system normal

DI system - system normal

EA/CC/ISC
Code 224 says Idle speed contact switch S29/3 fault

EZL system - system normal

OP system - system normal

PML system
Code 03 says (1) LR wheel speed signal error. (2) LF wheel speed sensor and circuit fault (W129/W140 since 94)
Code 04 says (1) RR wheel speed signal error. (2) RF wheel speed sensor and CKT fault (W129/W140 since 94)

ABS/ETS/ESP - system normal

BAS system - no ECU control or no data.

ADS system - data error

ASD system - data error

SPS system
Code 11 says Volts supply at speed sensitive power steering Ctrl module faulty.
Code 17 says no description

SRS system
Code 139 says no description
Code 03 says low volts, voltage supply circuit 15R

ICM system - no ECU control or no data

RST system - system normal

RB system - data error!

IRCL system - communication interrupted

PSE system - system normal

ATA system
Code 15 says IO SIG not received from interior motion sensor or button on interior motion sensor transmitter and receiver unit pressed at least once or infrared interior motion sensor control unit (N26/3) not present or defective

CF system - system normal

AC system - system normal

OCP system - No ECU control or no data
LCP system - No ECU control or no data
PTS system - No ECU control or no data
EIS system - No ECU control or no data
D2B system - No ECU control or no data

I wounder if it is worth looking at the wiring condition going into the module.
My logic doesn't work with the result says "Diesel" from EDS system.
Appreciate all the help to interprete the results.
 

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1986 560SEL, 1986 560SEL, 1992 500SEL, 1999 S500
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This is a cut and paste from a post I made a while back. Your fuel regulator may be allowing gas to be sucked into the intake directly causing a very rich mixture:::

I have had a similar problem for months but it is now fixed. My 92 500SEL would crank for about 10 seconds and then start, always with the smell of large amounts of raw gas. I was leading to an electrical problem since I knew it was getting gas--must be lack of ignition. So I did a major tune-up as with over 200k it was due. No difference. I then put a Fluke Scopemeter on the output of the crank trigger and noticed very uneven/missing signals to the EZL (ignition module). So I replaced that and there was no improvement.

After doing much study with WIS and Aldata I decided to go through the fuel system. The first step was to take the vacuum line off the fuel pressure regulator to see if it would close and stop the return to the tank. This might increase flow to the injectors in case the pumps were weak. I thought maybe it was getting gas but not enough to atomize and therefore didn't ignite but just passed through the exhaust. IMMEDIATELY the problem appeared!! The vacuum line was wet inside--with gas! The diaphragm in the regulator was ruptured and the manifold vacuum was sucking raw, pressurized gas into the cylinders. The fuel management system was no longer in control of all the mixture. I replaced the regulator, a five minute job, and the car starts like brand new.

The regulator is located in the fuel rail, on the V8's, on the drivers side by the firewall. It is about i"round and looks like a top hat with a short vacuum line running to the intake. You will need a set of internal snap-ring pliers and maybe Channellocks to twist it it out.
 

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1991 500SL
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Discussion Starter #14 (Edited)
Thanks. Will change the fuel pressure regulator, all upper & lower 'o-ring' of injector and post the results. Is it worth clearing the code as well at this stage?
 

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1991 500SL
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Discussion Starter #15 (Edited)
Change fuel pressure regulator, service all injectors o-ring (because no stock). No difference. Used hand held tester to erase code however the following codes cannot be erased.

EA/CC/ISC
Code 224 says Idle speed contact switch S29/3 fault

SRS system
Code 139 says no description
Code 03 says low volts, voltage supply circuit 15R

Try to start. The engine did not even turn. It make a series of click with all light flashing. I presume the battery is weak. Need to charge the battery and try to start it again.

How do i check conditions of Idle speed contact switch S29/3? Also what does it mean by low volts, voltage supply circuit 15R? Can mal-function ETA gives these problems? Is there suppose to be a code for bad ETA?

Appreciate all the help. Thanks.
 

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1986 560SEL, 1986 560SEL, 1992 500SEL, 1999 S500
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The S29/3 switch is on the back of the gas pedal. There is a jacketed cable under the carpet running up the pedal to the switch. The connector on the cable end is underneath the driver side trans tunnel carpet by your right foot. This tells the computer that the driver has commanded the throttle to be closed and compares with the closed throttle switch that is inside the Electronic Throttle Actuator (ETA). If the driver takes his foot off the gas but the ETA doesnt go to closed throttle the system will fault and go into "limp home" as a safety. Here is a diagram of the switch.
 

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1991 500SL
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Discussion Starter #17 (Edited)
Thanks chuckindetroit.
How do i check if both the throttle and ETA are closed? I have subscribe to ALLDATA and there are several tool which i believe needed to test the module. Is this necessary in this case? Where can i purchase these equipment (attach)? Or is there any other way to test the S29/3 switch.
 

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After the battery charged will the engine crank? Those are some mighty expensive high-end tools you might not even be able to get a hold of. A basic multi-meter is all you really need. Both the idle contacts should be closed when the gas pedal is not pressed. The one on the gas pedal can be checked by finding its' connector and checking with the meter. The cable on it can break inside the jacket due to continuous flexing as you drive or the switch may be bad or out of adjustment. I do not have handy a diagram of the inner workings of the ETA to give you a connector pinout. I will look for that.
I see there are also codes for the wheel speed sensors. Again, due to continual flexing as you turn the steering wheel, the cables to them will break internally over time. They are nothing more than a coil of wire in the pickup and can be read with an Ohm-meter. The specs for their resistance should be in Aldata somewhere. Put the meter on the leads and wiggle the cable back and forth to see if the resistance jumps (known as a swinger). If it does not remain steady you have a broken wire and the speed sensor will have to be replaced. The end of the pickup that is near the brake rotor may also be covered with metal dust/shavings as well the toothed ring on the rotor. These can be cleaned with compressed air.
 

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1991 500SL
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Discussion Starter #19
Yes, the engine crank after the battery was charged. Will check the idle contact at the pedal to start with.
Thanks.
 

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1991 500SL
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Discussion Starter #20
Chuckindetroit, I have managed to locate the gas pedal connector (S29/3x1).
What reading should i expect when the gas pedal is not pressed?
 
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