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S500L 03, Avalanche 03 and Porsche Cayenne S 04
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Discussion Starter #1
Hi guys,

What i thought to be a bad coil turned out to be something else. I get misfire on cilinder one and my engine does not idle nice. Engine shakes way too much. It was doing that for a long time cold but i never had check engine come on and did not bother much because it always stopped after 1 minute or so. My S500 has only about 20000 miles. I tested fuel pressure, changed all coils and the spark plugs and wires from cilinder 1 and i also checked fuel pressure which is 50 psi, i took out injector 1 and cleaned it. Seems to work fine, i then swithed the inector with the one from cilinder 2.Nothing seems to help. Vacuum hoses seem to be fine now, they where old and cracked so i changed them with some universal hoses. The maf sensor is in its place thightly so i dont see any problems there as well.
I get p0301 and p0300. When reading live data LTFT stays at 0 and STFT rises up to +25% for both banks. I have also changed the leaking valve cover seals and i have to do bank 2 again cause it is leaking badly now, but that has nothing to do with cilinder 1 misfire.
 

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2002 Mercedes S600, 2002 S500, 2001 BMW 750IL
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713 Posts
buy the compression testing gauge from the auto parts store and check the compression for cylinder 1. You may have a problem you cant see.
 

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S500L 03, Avalanche 03 and Porsche Cayenne S 04
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71 Posts
Discussion Starter #3
That is exactly the answer i did not want to read. You are thinking burned exhaust valve i guess. I have been searching for burned exhaust valves on a S500 but i could not find any info about it.
 

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S500L 03, Avalanche 03 and Porsche Cayenne S 04
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71 Posts
Discussion Starter #4
Ok compression test done and compression is good. 180 psi after 3 turns. Same as cilinder 2. So i guess valves and piston are fine. What should i do next? Do i need to take off the valve covers to check the valve lifters? Could there be something with the intake?
 

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2000 CLK 430 Cabriolet 2003 S500 4Matic 2004 S55 2005 CLK 500 Cabriolet 2008 S 450
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780 Posts
There are a number of things that can cause a misfire. As an example vacuum leaks, electrical leaks i.e. bad wires or bad coils or bad plug. My best advice would be to find a good Indie who has a STAR and have him check for codes.
 

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S500L 03, Avalanche 03 and Porsche Cayenne S 04
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71 Posts
Discussion Starter #6
I have the codes, no need for no indy. Vacuum has been tested as i wrote earlier, wires also and coils and plugs as well. I only get misfire on cilinder 1.
 

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Outstanding Contributor
2002 S430
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1,923 Posts
Shot in the dark next time before you start the car, when it is nice and cold check the fuel rail for pressure first.

Dean
 

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S500L 03, Avalanche 03 and Porsche Cayenne S 04
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71 Posts
Discussion Starter #8 (Edited)
I did do that, if i remember correctly it was 55 psi. I have a new fuel pump and filter fitted 4000 miles ago.
Also i recall when i started driving this car it started nicely and did not shake. It then started to shake cold but always disappeared after about a minute or something. Check engine never came on so i never bothered until shaking became worse and CEL came on.
 

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Current 2017 GLE350, 2007 S550, 2002 S430, 1998 ML320 Deceased 74 240D, 92 400E, 97 E420, 13 GLK350
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Just some basic thoughts.

Leaking breather and valve covers result in oil leaks onto plug wires and affect their longevity. Looks like you replaced the wires:
- Are the replacements Bosch or an off brand?
- Are the replacements the correct resistor wire corresponding to the stamp on the valve cover?
- Are the wires securely snapped onto the plugs?
- Are the wires in their correct position corresponding position 'a' and 'b'?

With new coil pack and plugs:
- Is the coil pack Bosch or an off-brand?
- Are the connectors secure at the three locations?

With new plugs:
- What type of plugs were used?
- What torque value was used?
- Did you put anything on the plug threads or the electrode?
 

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S500L 03, Avalanche 03 and Porsche Cayenne S 04
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71 Posts
Discussion Starter #11
Good questions!

Vacuum and breather are fine now i think. I did test the vacuum and all was fine.
The replacement coils are off brand. The original ones are still good i think. I did not notice any change when switching coils.

The replacement wires came off another car, should i try new ones? The wires are snapped onto the plugs. Should i try new wires?
There are short and long wires. I might have changed their locaton but i did put the long and short ones were they belong. a & b that is

Original plugs still, i have changed them with other used plugs also. They do spark. Fuel is coming like it should. I did not put anything on the plugs all i did was brush them clean. I just tightenend the plugs by hand.

What do you mean by are the connectors secure at three locations?

I have a Icarsoft MB scanner with misfire fault counter. No other cilinder has misfires. My short term fuel trim goes up to about 25% for both banks. There was also another function that i did not understand where only cilinder one got strange values.
 

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S500L 03, Avalanche 03 and Porsche Cayenne S 04
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Discussion Starter #12
I have taken off the intake manifold and it is very dirty. Is there anything else i should check besides the intake valves? Are there some known issues with these manifolds? When turning the crankshaft i can hear air escaping at cilinder 1 area.
 

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2003 S500
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The best test at this point would be a leak-down check. The engine is turned to TDC-Firing on the cylinder being tested (especially #1 in your case), and compressed air is introduced into the cylinder using a special test rig. The test gauge shows the amount of leakage, and just listening will tell you where it is leaking - rings, intake valves, exhaust valve, cylinder head gasket, etc. That would end the guessing...
 

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S500L 03, Avalanche 03 and Porsche Cayenne S 04
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Discussion Starter #14
I have a leak down test, just haven't used it yet seeing the results i got from the compression test. Now it is a bit late do do a leak down test with the intake manifold taken off.
 

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S500L 03, Avalanche 03 and Porsche Cayenne S 04
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Discussion Starter #17
Air is not escaping as far as i can hear when doing leak test on cilinder 1. I have not tested all cilinders yet. Seems to be around 10 percent at 85 psi.
 

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Any updates on this rik881?
I have a similar problem on bank 1 with, cylinder 2/4 no el from coil.
Swaped coils and saprk plugs.
Problem stayed on 2/4.
Constantly no el on coil.
Suspected ecu, went to electrician came back, says its good.
Dunno what to check next.
 
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