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W140 500SEL 1992
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22 Posts
Discussion Starter #1 (Edited)
Following on from my previous post..

http://www.benzworld.org/forums/w140-s-class/1664333-engine-wiring-loom-rebuild-uk.html

I rebuilt the Engine wiring harness/loom, however this did not fix the cars problems - the car runs the same as before the rebuilt loom was installed!!

so the engine wiring can now be eliminated from the possible causes.


Here are the cars sympoms:
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1. Very rough idle

2. MPG gauge is over to ZERO

3. No power, appears to be in 'limp-mode'

4. On acceleration MPG gauge is at ZERO, engine revs but no response.

5. Using lots of gasoline, as Fuel-Gauge has moved a lot since this started.


Have a think, while i make a video so you can see...

Back soon, Gaz.
 

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W140 500SEL 1992
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22 Posts
Discussion Starter #2 (Edited)
The MPG gauge is mostly at ZERO, I'm convinced that a lot a fuel is being used,
I have noticed that the Fuel gauge has moved from straight-up to 11 o'clock
in just the miles on the trip count. (13.5 miles)


Any advise and comments most welcome.

Please help me fix this car!!!:surrender:
 

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94 s420 250kmiles
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827 Posts
Take it out for a drive at night for about 4 or 5 minutes and check the exhaust headers see if they are glowing this will confirm you have an injector being held open

sent from my HD2 running Android 4.1
 

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W140 500SEL 1992
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22 Posts
Discussion Starter #5
All comments & suggestions most welcome

Take it out for a drive at night for about 4 or 5 minutes and check the exhaust headers see if they are glowing this will confirm you have an injector being held open
I need simple, detailed instructions that even a 6yr old would understand.

1.How do I check the exhaust headers?
2.What am I to expect? Literally glowing red-hot pipes?

please be more specific..
---------------------------------------------------
Also, i used an LED reader on the 38pin socket (pin4) and it was clear!

would I get an error code on pin4 if an injector was held open?

I also remembered that Cruise Control was working intermittently before these problems started.

On reading 38pin Socket(pin 7) I did get codes of; 3,5 & 6
however they were able to be cleared.I have been unable to use cruise control since the car runs so bad.

Could all this be linked to a bad computer module?
I noticed there is a module that controls both idle and cruise control
under the main lid of the 38pin socket.


Please give comments & suggestions all most welcome Gaz.:confused::confused:
 

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1997 S500V, 1999 S500 grand edition, 2006 s65 amg
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7,356 Posts
what is the condition of the throttle body? because i heard people rebuild the wires on those too. when they say glowing you will notice they illuminate at night. also check the cats because when my cats were bad i would floor it and the car would not rev and go at all. but that sounds throttle body related I am not positive but its an opinion
 

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W140 500SEL 1992
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22 Posts
Discussion Starter #7
what is the condition of the throttle body? because i heard people rebuild the wires on those too.
I have no idea of its condition - this would be on the list of possibilities..
would it have to be removed and inspected?

when they say glowing you will notice they illuminate at night
OK, where do I look?
Do these things normally glow in the dark??

also check the cats because when my cats were bad i would floor it and the car would not rev and go at all.
The car does rev, just thers no power to wheels..
How do I check the cats?
Is removal involved?

again thanks for your suggestions, I hoping for an easy/quick solution. Gaz
 

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W140 500SEL 1992
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22 Posts
Discussion Starter #8
computer modules

Could these units be causing problems?



Inparticular unit 4
It controls accelerator and cruise control?

please comment, Gaz
 

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1997 S500V, 1999 S500 grand edition, 2006 s65 amg
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7,356 Posts
the headers usually dont glow(exhaust manifold) that cat are tricky you can try to drive the car with no exhaust on it an see what happens. some cats rattle and others just get horribly clogged.
 

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1997 S500V, 1999 S500 grand edition, 2006 s65 amg
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7,356 Posts
well now some models are different i have seen some w140s that start at 0 and some that start at 40mpg my s500 starts at the far left
 

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1997 S500V, 1999 S500 grand edition, 2006 s65 amg
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7,356 Posts
wow, every min a learn something new . thanks guys and special thanks to nhzruthless818
your welcome to be honest i learned that from my former 92 300se and 93 400sel and when i got my 97 s500 i got worried that it was at 40mpg then went to the dealer and they said its normal so i think older models have it at 0mpg. also there some secrets to knowing what year the car is by looking at the factory cluster this is good to know so i will post this up.

98/99 has the bigger screen
97/96 doesn't have orange lines (97-99 have canbus connector)
95/94 have digital
92-93 analog (92-96 have multiple connectors)

i thought somebody might need that. but alot of the analogs were replaced at dealers to digital.
 

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1995 S500 coupe, 1990 Mazda Miata
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694 Posts
From page 83 of the owner's manual pertaining to the fuel consumption gage: "Due to system design, maximum consumption is indicated at idle speed". I would try unhooking the catalytic converter, which means running it open header on the passenger side, and see how it runs. With the bad engine harness, it's possible that your converters are plugged from possible misfires.
 

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W140 500SEL 1992
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22 Posts
Discussion Starter #16
ETA - throttle body

I cut the outer sleeve on the ETA cable to reveal GOOD condition wires,
they looked like new.

so I then turned ignition-key to 2nd position and propped the gas-pedal with a length of wood.

I could hear the ETA humming and on pushing/pulling the throttle cable from under the hood, could see the butterfly opening and closing smoothly.

seems fine to me..
 

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W140 500SEL 1992
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22 Posts
Discussion Starter #17 (Edited)
Spark Plug Condion

Removed spark plug to reveal BLACK SOOT covering the tips.
Indiction of OVER-RICH mixture/fuel not burning.





are they plug getting a spark?
 

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W140 500SEL 1992
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22 Posts
Discussion Starter #18
Distributor Caps 1

Lets have a look at the condition of the caps and rotors..

probably should change this....

or at least clean it...



But no leaking from cam-shaft...


Better just check the other one.....
 

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Premium Member
1997 S600 (sold)
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4,660 Posts
I would worry about plugged cats. Disconnect the cat pipes and start the car. See if it runs better. Or buy an exhaust back pressure gauge and check exhaust back pressure.

I would also replace those distributor caps and rotors and spark plugs.

Brett
 

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W140 500SEL 1992
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22 Posts
Discussion Starter #20 (Edited)
Distributor Caps 2 - Hilarious xD

Hang on, whats this??



oh jeez! TOTAL DISINTIGRATION:eek: But wait, Thats it!:):)

Rotor Arm adaptor had somehow snapped off and mangled all the components inside the Distributor.
Now I know why there was Rough Idle,Zero Power and huge fuel consumption...I was running on 4 cylinders,MAX!! :p


Using insides of distibutor as a coffee grinder


I actually started uncontrollably laughing after discovering this, it ALL made perfect sense at last.

I will order the replacment parts and look forward to installing them.

There is now a massive beam of light directly overhead,
before this there was only a glimmer, a twinkle of light
and it was a million miles away.!!:thumbsup::thumbsup:Gaz


 
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