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Discussion Starter #1
Hi folks, my car with 60K on it, overnight developed this misfire. Ran perfectly for the 6 years I have had it up until this issue. Pulled coil from 6 and swapped it with #5 and still same code; Misfire on 6. Swapped them back then swapped spark plugs between 6 and 5 with same result. Now I'm scratching my head. Any ideas on what to try next would be much appreciated. BTW spark plugs were in perfect condition on both cylinders. Using BlueDriver scanner and software to read codes.:unsure:
 

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Go upstream. Surely the coils are controlled by some module.
 

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Discussion Starter #3
Thanks for the help here: I removed the coil on 6 with the engine running and saw spark jumping from the end of the coil boot to ground as I gradually pulled it out of the hole so I know the coil is firing, then for good measure I replaced it with a new one with no improvement. The spark plug worked perfectly in #5 when I swapped them so I know the plug is good. Also when I pulled it from “6 cylinder it didn’t have any gasoline oder or residue. It did look perfect with no black carbon buildup at all. This leads me to suspect a lack of fuel like # 6 injector is not functioning. Hope I can get this forum of experts to help me pinpoint the malfunction. Any further insight with a way forward is very much appreciated.
 

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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG
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Swap injectors, if problem persists it's the ECU.
 

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Discussion Starter #5
Love your moniker! Getting to the injectors on this motor is a big job which I will do if I am sure this is where the problem lies. Is there any way to safely test the injector? I don't know at what voltage they operate but if I did, does anyone of the experts here know if I applied that voltage to the injector terminals, would an audible click or the lack thereof confirm the unit works or not?
BTW I had to rejoin this forum recently when my email changed so if it looks like I am a newbie here I am not. I am however a retired federal agent with a professional licence in engineering so I'm undaunted and actually enjoy and am entertained by solving these types of issues. I cannot remember the last time I paid anyone to work on a car and intend to keep it that way, so with a large array of tools and a hoist in my garage, in the interest of marital harmony I need to get this fixed and get her car back on the road...
 

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If you're going to do the injectors, maybe this is a good time to inspect your intake manifold. Get a gasket for the manifold and get new O rings for the injectors. Get at least one new injector for good measure and install it where you suspect the issue might be.
 

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Discussion Starter #7
Does this vehicle have issues with the intake manifold? If so is there any historical data on this sight that would give me any insight about what might have preceded a intake manifold failure?
 

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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG
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These engines are known for intake manifold runner issues. They will set a code, but no check engine light.

Removing injectors isnt a bad job....intake manifold removal not required.

Just have to clear the space around it and move the wiring harness a bit, and then you can take off the whole fuel rail at once.
 

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1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG
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Use a stethoscope on the offending injector and listen for a click. These operate at battery voltage, but are PWM. You may have a dead or leaky injector, which may lead to a consistent misfire.

If swapping injectors still has the same problem, then at that point you have either a bad ECU, or bad valves (chipped valve or not seating right).
 

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Discussion Starter #10
These engines are known for intake manifold runner issues. They will set a code, but no check engine light.

Removing injectors isnt a bad job....intake manifold removal not required.

Just have to clear the space around it and move the wiring harness a bit, and then you can take off the whole fuel rail at once.
Yeah getting the intake manifold out is more of a trick, but do you think if I were to apply say 12 V DC to the injector itself I could learn if the electrical component of the injector was functioning by hearing it click or not hearing it?
 

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Discussion Starter #11
I pulled the entire fuel rail from my other ride and rebuild the injectors using a 9 V battery to actuate each injector While flooding it with injector cleaner turning the injector on and off until the spray began to atomize evenly. I can’t imagine this injector system works any differently. What say you?
 

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Discussion Starter #12
Sorry deplorable did not see your first post about the stethoscope I will do that then report back.
 

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Discussion Starter #13
OK here's what I learned today. Didn't hear anything from #6 injector with fuel rail in car, my garage is perfectly quiet and did not have my stethoscope on as it was hard enough getting voltage to the terminals. After removal of rail I got a buzzing sound from all injectors just hitting them with a 9 volt battery. No stethoscope needed to hear any of them. Hate to just throw cash at an ECU without any more evidence ten that... Is there something I'm missing or anything else I should try??
 

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1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG
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Now would be a good time to swap injectors since you removed the fuel rail. Move #6 to #1 and vice versa.
 

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Yes, it'll bleed itself after first or second crank.
 

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Discussion Starter #18
Ok Deplore, cleaned injectors and ports with injector solvent and greased their o-rings. switched # with #6 and car runs like before. CEL still lit. My scanner still shows misfire on 6 and comes back even when i clear the codes. Just drive it util CEL goes out or problem returns? Was it a possible vacuum leak I fixed with grease or cleaning the injectors?
 

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1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG
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Okay, it's currently not looking good.

Next step would be pulling out the coil and spark plug for #6, plug in coil to harness, plug in spark to the coil and leave it dangling outside. Start the car.

Do you see spark arcing on the spark plug?
 

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Discussion Starter #20
Whoops Looks like i was not clear in my last message. When I said "runs like before" I meant to say the misfire was fixed! And it runs like it always had for the last 30K miles, as if it never had a problem. The only issue is that the CEL is still lit.
Scanner still says it has a misfire on #6 and I can't clear the P 0306 code without it coming back on. I drove it 20 miles and still is lit. Disconnected battery then for 30 minutes and still there. Do I need several warm up cycles for the ECM to clear on its own?

Sorry to have misled you:confused:
 
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