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1996 C280 Sport
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321 Posts
Discussion Starter #1
Well I've been trying to get my car in running order. It's a 96 c280 sport with 170k so far. Head gaskets been replaced also a new Wiring harness, water pump, and hoses.
That's the history. I'm here today because I cleaned my throttle the other day, not a hard process cleaned it re-installed.

I start the car now in the mornings and for a second it shoots up to about 2000 rev. than calms down a bit I've checked vacuum leaks and right where my sparkplugs are located a vacuum line trails them as you can see in the pic. All the plastic is brittle and had broke so I replaced a bit of it.





In this picture you see the EGR valve to your left but what is to the right ??? under the MAF sensor ??? I ask this because the vacuum line that goes by spark plugs comes out the side in the back of the engine and was not connected with the part under my MAF. Is there any reason I found it like that ??? Bad mechanic ??





One last thing. Here is a pic. of my throttle linkage or the part you can adjust. As I stated earlier about the shot to 2000 Revs. I turned this to the right clockwise I would say and it seemed to change it a bit. Can I fix that issue with this Apparatus ???






I really enjoying working on the car (besides my back bahahaha) But I need a bit of knowledge If anybody has clues, Ideas, suggestions post please !!! It would be cool to help someone else out later down the line :p

Thank you (Dankeschön) :cool:
 

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2001 CLK55 AMG, 2002 C32 AMG
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1,637 Posts
lol, sorry i cant help you, i have the 4 cylinder. im not sure what that component is. i used to have a w202 repair cd before my dog decided to chew on it, so now i cant even look it up for you. good luck, hopefully someone who knows more about the 6 cylinders will reply.
 

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1996 C280 Sport
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321 Posts
Discussion Starter #4
It's all good :p Thx though.

Ya I need to figure out that throttle issue :p I would mess around with it but knowing my luck I'll break something ha !

Anyone else care to give it a try ? :confused:
 

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2001 CLK55 AMG, 2002 C32 AMG
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1,637 Posts
do the rpms fall down to normal values after a minute or so? it could be due to a cold start. not sure where your located... *nvm california doesnt get too cold.

also, how did you clean the throttle body? did you get any cleaner on the maf?
 

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1996 C280
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151 Posts
that is the shut off valve which is a part of the EGR system. It should have a vaccum line attached to it. one line coming from the spark plug area goes to the EGR and one goes to the shut off valve
 

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1996 C280 Sport
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Discussion Starter #7
Thanks wammer and liquidusculade !! If the shut off valve is going bad what are some symptoms if you know any ??

And by going to the EGR you mean the Changeover box that's in the front of the engine correct ??

It only shoots up for a split second to 2000 rev. after that it drops to about 1000 rev. kina sits there for a sec and finally goes down to 800 rev. :eek::eek::eek:

First time I did it I didn't know how to pop off the ball joint in back that's connected to the linkage so I sort of left it connected.
Now when I started the car after I cleaned it it idled at 2000 rev. due to me not dropping the top of the cable in the third picture down into it's spot which I immediatly jumped out of the car and put it back in.

(if you don't know what I'm talking about refer to the third pic of the cable that goes to the throttle linkage... where you can screw it up or down you can pull the cable up and if not dropped in correctly can get stuck on the side)

That is when this occurred. Did I possible stretch the cable or linkage somehow ?? :crybaby2:

The second time I cleaned it I took everything out and all was the same. It also will not hold an idle in park, very seldomly though. It will bounce up and down from 500 to 700 I have to gas it to get it to idle right or re-start engine :/

Never got cleaner on MAF and it looks sexy ;) But The air duct above the engine has a sensor on it 02 I believe ?? It is super dirty would this cause that problem ?? It's a tiny sensor
And That cable that goes to the linkage what exactly does that adjust ??

Thank you ALL !!!! :D
 

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2001 CLK55 AMG, 2002 C32 AMG
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there is an air temperature sensor after the maf and close to the throttle body. is this the sensor your talking about being dirty? the temperature sensor feeds into the ecu to help calculate the air/fuel ratio.
 

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1996 C280 Sport
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Discussion Starter #10 (Edited)
That's the temperature sensor !!! ??? I searched for like hours yesterday trying to figure that out :p AWWWW

I called my Indie and Used parts guy and they said they needed to see it. lol

I just went and cleaned it with some throttle body cleaner and noticed that there was actually a little red ball at the end I never saw due to the dirt.
Cleaned and it seems as if it's back to normal (besides the hissing)
Does this cause issues as I've stated ??

I plan on doing a vacuum check today found some diagrams of all the lines.

I'm going to try and pin these today

You kick ass liquidusculade :cool: Thanks :)

Also I hear hissing under my Intake manifold and it seems as if my fuel pump is hissing actually its more of a buzzz it's odd ..... Is this a sign I should change it ??
 

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2001 CLK55 AMG, 2002 C32 AMG
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glad i could help. where is the hissing coming from? do you hear it in the engine bay? i wouldnt be too concerned about the fuel pump... i think it makes noises, at least i hear mine before i ever start the car.
 

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1996 C280 Sport
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Discussion Starter #12
It seems as if it's coming from a hose connecting the bottom of the intake manifold. The hose clamp is in the middle as if it got loose and moved up. I don't feel any air leaking though. There is what seems like an oil filter behind the throttle body Could that be it ??? Sorry I'm such a newb :bowdown:

The fuel pump makes the noise all the time. I just either noticed it or it just started happening lol :p

I have a leaky rear axle as well :( I think It needs a new gasket
 

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2001 CLK55 AMG, 2002 C32 AMG
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im not too familliar with the 2.8L. Is it the bottom of the manifold or the intake piping before the throttle body. also, not sure whats behind the throttle body without seeing it. i think your throttle body is on the lower driver side beside the engine, so maybe the starter is down there...

hopefully someone who has a 2.8L can help more lol.
 

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1999 C43 AMG, 1998 C43 AMG
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604 Posts
It only shoots up for a split second to 2000 rev. after that it drops to about 1000 rev. kina sits there for a sec and finally goes down to 800 rev. :eek::eek::eek:
That's pretty normal. The ECU detects that it's a "cold" start (read, not at normal 80C operating temperature). The ECU forces the RPMs up for a bit to prevent a possible cold-start stall (very normal on old carb'ed cars). Once the ECU detects there is no impending cold-start stall, it starts to lower the RPMs in increments back down to idle--which is typically 600rpms. 800 is a tiny bit high, but I wouldn't worry about it. Sounds normal. I can take a pic of the vac lines on the left side of my m104 and report back for you. I know my lines haven't been disturbed since the factory.

But you did mention cleaning the throttle body. Did you happen to remove it from the car for the cleaning? I ask this because its got the same wiring issues as on the engine wiring harness. So, if you disturbed that cable that connects the throttle body to the car you could have easily caused some issues there. Don't fret, it sounds like you've been bitten by the DIY bug. There is a recent write-up on how to re-wire the throttle body yourself with minimal electronics experience. I plan on doing this job twice (My C280 and my E320).
 

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I'm driving a 1999 C-class C220CDI.
Car is driven very little (2500kms/year - total mileage = 74000kms). On highway, rpm's seem not to go above 3000rpms anymore, and turbo does not kick in. I've been told this is due to dirty EGR valve.
Is this correct, and how can I clean it myself?
is fuel additive effective? Wynn's should have a good product on the market.
Anyone with the same issue?
 

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1996 C280 Sport
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321 Posts
Discussion Starter #16
I'm wasn't really sure about where the sound was coming from. I took a closer look and it seems as if it's coming from my intake manifold. Like shooting air through it. Is there any manuals to take off the intake manifold correctly ??? :) I would love one :confused:


Should I get a new Air Temp. Sensor ???

Saluco I did unhook the cable for the throttle body to remove it. Before I bought the car though It had a new wiring harness installed.
I hope it still didn't cause a problem How can I check that ??

I also had the oil lamp come on and off driving to work tonight :eek:
My oil is 3/4 full been checking it recently due to oil spills by my air pump
But no spots on the ground at all :p I don't understand it I hope it doesn't ruin this alternator !!:crybaby2: lol

Thanks for all the feedback as well ::appreciated::
 

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1999 C43 AMG, 1998 C43 AMG
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oil leaks are, unfortunately, pretty common on the m104. with the exception of the head gasket, they're not really dangerous. i've had one that covers my alternator and vac pump for more than a decade with no problems.

the only way to test the wiring on your throttle body is to take a scalpel or exacto knife and cut into its black insulation to take a peak at the 12-15 wires inside it. if their insulation looks corroded and degraded, you've likely got your culprit their. if you're remotely handy, you can rewire that thing. you basically build a new one with all new wires, keeping the tip of your current one so you can plug it back in, but it does require that you be able to solder the new wires onto the circuit board inside the throttle body. I have heard of people who have never even used a soldering iron pulling this job off. if you don't feel like it, you can drop the dime on a remanufactured one. they run about $700. I recommend trying to remanufacture your own, obviously.

as for the hiss, sounds like you unplugged one of the 2 different vac lines around your throttlebody and intake. there are two of them that come down, merge, and connect into the intake on the front side of the intake, just above the throttle body.
 

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1996 C280 Sport
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Discussion Starter #18
Ya That seems to be where mine is. With the exception that my alternator is soaked with oil like you said. The last alternator I had got murdered by that oil. :(:(
I will never see spots on the ground though.









What would trigger my oil light to go on though. On the Freeway it was on and back off and on again. Drove it home it didn't do it ... :confused: ???

Ya that sounds like something I could do The wires look fine though I've checked it out. A ok


As for the Hiss I took a look today and put my ear on the intake manifold. Either I'm trippin or it's on the inside. There is also two hoses with clamps on them at the bottom of each side of the manifold. I bet one of the clamps is loose. That is why I asked about a DIY for the Intake Manifold so I can get to that hose in the back I can't get my hand in there to tighten it :) I'm going to keep searching though.


Thx for the replies :D


99c220cdi
I believe

http://www.benzworld.org/forums/w202-c-class/1526656-egr-cleaning.html

This should help
 

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I would dearly love to see the pics but they are "moved or deleted". Is that Photobucket's problem or is this forum somehow losing them? Hmmmm.
 
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