380SE Running Rough - Mercedes-Benz Forum
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post #1 of 14 (permalink) Old 12-02-2017, 09:59 AM Thread Starter
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380SE Running Rough

Hi everyone,

I just bought a 380SE and it’s giving me more problems than I anticipated. When I picked it up, it was running ok, with a slightly erratic idle and occasional long crank. I drove it around the block and it shifted and ran fine, a little rough but fine. It would sometimes die when I gave it gas. I figured it needed something minor.

For the occasional long crank, no start, and stalling under throttle, I replaced the fuel filter and check valve, which helped. I then replaced the plugs which were mismatched and fouled. It helped a bit more. After these changes the car started right up on first crank stalled less frequently.

I then realized the car had a pulsing idle. It would go from about 500-1000 RPM steadily. I took off the idle control module, the electronic that is mounted on the bulkhead, and the idle smoothed out and it stopped stalling completely. It now idled too high, but never stalled. At this point I also realized there was some white smoke and water from the exhaust. I order a used idle control module and threw it on thinking it would solve the problem, but now it runs worse.

What could be the problem? It runs rough and still stalls? Could the replacement idle control module I got be bad as well?

Any help would be appreciated! The car is clean, rust free, and has 90k on the odo, which doesn’t work. But judging by the wear on interior bits and general shape of the car I bet it doesn’t have more than 130k.

Best,
Yousef
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post #2 of 14 (permalink) Old 12-15-2017, 08:37 AM Thread Starter
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Hey everyone, after doing some more research I think the problem might be that the fuel injectors are fouled up. I wrote in to Mercedessource.com, and the person who responded seems to think that's the case as well. I tried over the weekend to pull them out, jump the fuel pump and take a look at how they are performing. Using a crows foot and some creativity I was able to loosen the nuts that hold the fuel lines onto the injectors. I hit the allen head bolts that hold the plastic injector housings in with PB blaster to loosen them up, though one head is a bit rounded, the rest look okay.

1: Does anyone have any advice on dealing with rounded allen head bolts on the injector housings?

2: The only thing that's really in the way besides the throttle linkage on the passenger side bank, is this black rubber tube on the driver side bank, what is it and how do I remove it to get access to the injector underneath?

Any help would be appreciated!
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post #3 of 14 (permalink) Old 12-16-2017, 09:21 AM
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The black rubber tube looks like the idle air supply. It just pulls off, new ones might be needed.

Shame about your rounded bolt. I was very scared of doing that so bought a nice quality socket for the best fit. I suppose you could try getting the next size tool and banging it in. Not sure if I'd want to be using too much force there though.

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post #4 of 14 (permalink) Old 01-27-2018, 02:15 PM Thread Starter
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Thanks ianrandom, unfortunately I wasn't able to even get that far. I am afraid to round the hex pattern bolts that keep the injectors in place. I hit them with PB and tried removing them with 5mm hex tools, regular allen wrenches and then a socket, no dice. If I apply force, the hex wrench or socket will just slip, rounding the bolt. I have no idea what to do, I can't remove these injectors to clean them. Any advice on getting these stubborn bolts off?! I'm considering throwing in the towel and having it sent to an indy shop... What do you all think? I would love to do this myself but I don't want to risk rounding off these bolts...
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post #5 of 14 (permalink) Old 01-27-2018, 04:12 PM
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try pounding a torx bit socket into it then turning slowly back and forth till loose
after that try drilling in center and use easy out
thats how the pros will have to do it
take your time it will work
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post #6 of 14 (permalink) Old 01-28-2018, 02:55 PM
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Just run seafoam through the fuel system don't take off the injectors

Also did you change distributor cap rotor and the coil ? Change all those , it's time
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post #7 of 14 (permalink) Old 01-28-2018, 06:30 PM Thread Starter
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I've managed to get the injectors out, by using the torx bit method. The bolts need to be replaced now however, and I can't seem to find them online. Does anyone know the part number or what the bolts that hold the injector clips on are called?

Tusabes, I ran seafoam through it and it seemed to not make much difference. I will clean the injectors with an ultrasonic cleaner and that should hopefully clean them enough. I will do this next weekend and share the results!
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post #8 of 14 (permalink) Old 02-17-2018, 07:06 PM Thread Starter
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Quote:
Originally Posted by 29Hersey View Post
try pounding a torx bit socket into it then turning slowly back and forth till loose
after that try drilling in center and use easy out
thats how the pros will have to do it
take your time it will work
Thanks 29Hersey, that worked like a charm.
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post #9 of 14 (permalink) Old 02-17-2018, 07:23 PM Thread Starter
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Hey everyone thanks for your input.

I just finished reassembling everything. I replaced two injector seats, as they were cracking. I also replaced all the injector seals and that air supply hose on the right side.

The injector cleaning seemed to go well, after dozens of treatment with the ultrasonic cleaner and a week soaking in carb cleaner they went from a rust-tinged and oil-stained brown to shiny metallic grey (see pics before and after)

Re-installation went as smoothly as I could have hoped, but it's very tough working around the injectors and in those tiny spaces.

Anyway, with the cleaned injectors installed, the car fired right up! It seems to be running MUCH MUCH better, however, it still stumbles and stalls occasionally, though much less than before, when it would barely idle for 5 minutes, and erratically. Now it idles smoothly and sounds much better when it revs up, with only an occasional hesitation. It does occasionally stall, though, which is very disappointing.

Could I have misdiagnosed the main issue?

Or is the car just working through the mix of whatever was left in the tank when I picked the car up (the previous owner claimed to have put fresh gas in it), the new gas I put in it, and the seafoam? Maybe as the seafoam works through it will improve, and once I put a fresh tank in it will be fine?

Or am I just deluding myself and the occasional stalling is being caused by something other than the injector problem?

It seems that the injectors did need a good cleaning no matter what, but what should I do next to diagnose the occasional stalling? Should I just gamble and replace the distributor cap rotor and the coil as tusabes recommends?
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post #10 of 14 (permalink) Old 02-20-2018, 06:41 AM
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Yousef, what does the economy gauge look like at idle. Wonder if you have a vacuum leak. It should be pegged to the left at idle.


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