Loss of power/bad idling (e420 1993)

[denokande]

Hi guys!

Im going crazy with this problem...
Let me try to explain.

Car was running perfectly fine and i was driving on the highway.
Suddenly it lost power and was misfiring, i stopped to see what was going on and i noticed that the car was very shaky.
It is shifting gears strange.

A couple of months ago i've changed rotors, caps, camshaft seal, fuel filter, CAT and some more things.


After this happened now:
I ordered ignition cables and resistant free spark plugs.
The misfire is gone. But the car still has no power.
The car is now idling good but every 5-6 seconds it drops rpm to 500 and wants to shut off.
It feels like it is in limp mode while im driving it.
The car wont rev more than 2000rpm when i hold brake and going on the gas in D.
Its shaking a lot more in D and R than in P and in N.
It behaves same wether it is warm or cold.

Ive done a smoke test and it doesnt have leaks anywehere besides on the EGR gasket (i've ordered this).
All vacuum lines seems perfectly fine and the harness also seems relative fine.

I've disconnected MAF, the car is running exactly the same with the MAF disconnected. Ive measured it with multimeter and i have signal coming to MAF.
The throttle body is opening/closing, but i can see like brown residue (it looks like its been a little bit burned).
Ive followed all vacuum lines and all is good, also to the EZL.

I've tried to scan for codes:
2 HFM Sensor Voltage too high or too low, may open circuit (This one didnt come back)
11 O2S 1 Signal, short or open circuit (This one didnt come back)
32 (No description)

10 Resistance too high Fuse F2 or ECU (n16/1) Malfunction (This one didnt come back)
11 Resistance too high Fuse F3 or ECU (n16/1) Malfunction
12 Resistance too high Fuse F1 or ECU (n16/1) Malfunction
13 Resistance too high Fuse F4 or ECU (n16/1) Malfunction

Ive checked all the fuses in the BM, all of them is fine.


Can someone please help me further, im totally stuck.

 

[denokande]

Ive got these codes today,
1st picture before deleting, second picture after deleting codes.

Ive checked all fuses in BM module, all are fine.


Is these codes ”limp mode” codes or do they point to something?

My throttle only seems to be openinh in mechanical mode, opens about 30 degrees.

 

[emerydc8]

I've disconnected MAF, the car is running exactly the same

Maybe the @gsxr or the @gerryvz can chime in here but I don’t think this is good. The engine should run differently with the MAF unplugged. Also, I don’t think there is a “code” for limp home mode but by your description it sounds like it is in limp home mode. The question is what’s causing it. Do you have a spare base module? Spare ignition control module?

I’m not familiar with the scanner you have but it could be throwing false codes if the base module fuses are okay. I would try a blink code reader to double check codes. N16/1 is the base module containing those fuses.

 

[gerryvz]

What model car are you testing? A 500E or E500 with Bosch LH injection and M119 V-8? What model year? Which engine and injection system?

I also have never seen that scanner, and I wouldn't trust its output. For the 500E/E500, and LH cars of that generation, you should only be using the HHT (original MB dealer hardware), HHT-Win (as part of a Star/DAS C3 or C4 unit with laptop), or a blink-code reader (which will give you about 80% of all codes, but not everything). There are a couple of other units, such as ones way out of production by Snap-On and Trisco that can pull codes and reset, but these are very rare nowadays. The HHT-Win way is pretty much the best way to go.

We need the fundamental questions I asked above answered first, before we can properly diagnose your situation.

The primary focus of this forum is the V-8 powered W124 models, though we can and will help with other (related) chassis such as the R129, W140 etc. if they have the same engine/transmission, and/or are from similar model years as the 500E.

 

[denokande]

Thanks for responses @gerryvz and @emerydc8. I dont have any spare parts for it. It's a E420 -93 (m119.975 engine code) V8. I'm making a blink code reader tomorrow (cant wait 3 weeks for delivery), i'll come back to you with more info once i test it.

 

[nocfn]

I had bosch out of the box bad plug and this was determined with live data after I had started with baseline with everything new but the spark plugs because they were New...

 

[denokande]

I had bosch out of the box bad plug and this was determined with live data after I had started with baseline with everything new but the spark plugs because they were New...

Did you have same symptoms as me? I know the mechanic didnt gap them at 1mm, but im assuming the car wouldnt have all theese symptoms because of this.

 

[denokande]

Pulled the codes with blink reader.
@gerryvz @emerydc8 @nocfn

PIN 4- code 1
PIN 6- code 30
PIN 7- code 14
PIN 8- code 13
PIN 16- code 33
PIN 17- code 1
PIN 30- code 5 and code 8

 

[gsxr]

Pulled the codes with blink reader.
@gerryvz @emerydc8 @nocfn

PIN 4- code 1
PIN 6- code 30
PIN 7- code 14
PIN 8- code 13
PIN 16- code 33
PIN 17- code 1
PIN 30- code 5 and code 8

Read this thread for information on pulling codes, and use ONLY the PDF file attached in that thread to look up what each code indicates.

PIN 4- code 1 - LH-SFI, no faults​

PIN 6- code 30 - ASR - This is a "ghost code" which appears every time limp mode occurs.​

PIN 7- code 14 - E-GAS - Closed throttle position switch (S29/3)​

PIN 8- code 13 - BM/GM - Base module (N16/1) voltage supply output fuse F4, open circuit.​

PIN 16- code 33 - HVAC - Compressor cut-out control unit, short-circuit/open​

PIN 17- code 1 - EZL, no faults​

PIN 30- code 5 and code 8 - SRS/airbag - Left front seat belt buckle switch (S68/3) and Voltage supply circuit 15R​

Misfires will generally not store codes. Sounds like you no longer have misfiring. The ASR light will come on during limp mode. If you still have limp mode, and code #14 is the only fault from pin 7 (E-GAS), double check the throttle linkage adjustment first. Next would be to test/replace S29/3 (details here).

 

[denokande]

@gsxr
Thanks for reply.
I've just ordered the S29/3.
I've checked how to adjust the throttle linkage below, on step 7 it says it should be WOT (wide open throttle)
Does it mean the throttle body should be wide open? My throttle body now only opens about 45 degrees (should open 90 degrees when not in limp mode?)
When i push it with the finger it opens 90 degrees.

https://www.500eboard.co/forums/misc/Manuals/Servicev3.2/W124/w124CD1/Program/Engine/119/30-1010EA.pdf

 

[gsxr]

I've checked how to adjust the throttle linkage below, on step 7 it says it should be WOT (wide open throttle)
Does it mean the throttle body should be wide open?

No, just that the linkage is in the "WOT" position.

My throttle body now only opens about 45 degrees (should open 90 degrees when not in limp mode?)
When i push it with the finger it opens 90 degrees.

This is normal. The ASR ETA's will only open halfway/45° via the mechanical linkage. The internal electric motor is required to open fully/90°.

 

[denokande]

Okay, thanks for clarifying this. I'll adjust the throttle linkage and replace the S29/3. I'll get back to you when its done.

 

[denokande]

I got curios to see what the cable looks like going to the throttle body. I seem to have found what is causing the car to be in limp mode…