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1999 e320 RWD
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Discussion Starter #1
Was wondering if anyone has experience with this before:

I have a 1999 Mercedes E320, 280000 kms, was cruising on the highway being a bit agressive (but not too much), then I see check engine light go on and blinking, then turns solid.

All of a sudden car starts running rough with very weak power. I couldn't drive it home and had to tow it the next morning to the repair shop.

Indie shop scans the code, said engine is misfiring, said might be spark plus but I replaced spark plugs 4 months ago. They looked into it some more and said '3 of the 4 injectors are not opening fully', looks like electrical problem. They tried to identify root cause, even tried 'another computer', but couldn't find the cause.

Indie shop recommended I send the car to the dealer since they have more 'advanced equipment' that can troubleshoot the problem.

So that's where I am right now, my appointment with the dealer is next week.

I've benefited a lot from this forum, and have been able to identify many common problems with these e320s that I've had before (rear window regulator failing, front spring rusting out), but this particular problem I'm having no one seems to have reported before.

Any ideas what's going on?

Thanks! :)
 

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W124/230E, W202 C240 stationwagon, W210 E280 facelift
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366 Posts
Was wondering if anyone has experience with this before:

I have a 1999 Mercedes E320, 280000 kms, was cruising on the highway being a bit agressive (but not too much), then I see check engine light go on and blinking, then turns solid.

All of a sudden car starts running rough with very weak power. I couldn't drive it home and had to tow it the next morning to the repair shop.

Indie shop scans the code, said engine is misfiring, said might be spark plus but I replaced spark plugs 4 months ago. They looked into it some more and said '3 of the 4 injectors are not opening fully', looks like electrical problem. They tried to identify root cause, even tried 'another computer', but couldn't find the cause.

Indie shop recommended I send the car to the dealer since they have more 'advanced equipment' that can troubleshoot the problem.

So that's where I am right now, my appointment with the dealer is next week.

I've benefited a lot from this forum, and have been able to identify many common problems with these e320s that I've had before (rear window regulator failing, front spring rusting out), but this particular problem I'm having no one seems to have reported before.

Any ideas what's going on?

Thanks! :)
also common problems with the V6 engines are the high tension leads or ignition coils, your workshop maybe able to identify this by exchanging the wires of the misfiring cylinder with the good one, from the actual value (smooth running) they can see if the problem goes to the other cylinder, that goes also with the ignition coil, its just a matter of changing parts one by one to locate the faulty part. hope this helps.
 

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E320/E250 Bluetec Ford F350 6.7l
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35,886 Posts
There are 2 major ways to approach the problems for DIY.
1. You can spend hundreds of $$ and let the dealer scan the car and troubleshoot, hoping you will find a technician who knows what he is doing (that seems to be the biggest problem)
2. you can relay on "statistics" and replace few parts based on forum members experience and intuition.
Your model is having known weak point being MAF. Those things fail for no good reasons and not having additional sensor monitoring their work, they will trigger bunch of misfire codes.
Your symptoms fit under general description for MAF failure, so I would start with spending about $160 for new MAF and go from there.
 

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2017 Police Interceptor Utility, 2017 Police Interceptor Sedan
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Indie shop scans the code, said engine is misfiring, said might be spark plus but I replaced spark plugs 4 months ago. They looked into it some more and said '3 of the 4 injectors are not opening fully', looks like electrical problem.

Any ideas what's going on?

Thanks! :)
Considering that an E320 has six injectors, one wonders what the remaining two are doing.
 

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1999 e320 RWD
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7 Posts
Discussion Starter #6
Thanks everyone for the replies. I'll check with my mechanic and see if he considered the MAF. He's usually good. This is the first time he sends me to the dealer.

I'd love to DIY, but I'm a computer expert, not a car mechanic. If my car was a computer I'd have fixed it no no time :).

But as the car ages, and problems like these pop-up. I can see that DIY would make things more economical. And i'd love to DIY and learn my car inside out. i want to keep this car forever. But is it really realistic for a complete novice to learn how to DIY without messing things up even further?
 

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1999 e320 RWD
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7 Posts
Discussion Starter #8
Ok so I called my mechanic to check if he considered the MAF. He actually did try replacing the MAF, also did try switching out the ignition coils with good ones. Problem did not go away.

So looks like he did try everything you guys are suggesting, and so he suspects the ECU might be the problem, but it's a very expensive part to replace, so that's why he suggested to send it to the dealer they'll be able to better diagnose if the problem is the ECU or something else.
 

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1999 e320 RWD
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7 Posts
Discussion Starter #9
Just as an update to whoever's interested. Dealer said right side catalytic converter needs replacing. They disconnected it, and car worked fine. So I'm going to go ahead and replace it. Not a cheap repair, but watchya gonna do.
 

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'01-E320 & 02-ST2
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31,633 Posts
Just as an update to whoever's interested. Dealer said right side catalytic converter needs replacing. They disconnected it, and car worked fine. So I'm going to go ahead and replace it. Not a cheap repair, but watchya gonna do.
Please click user cp and edit details to add your vehicle and location to your profile, it's useful information when you're seeking assistance.

FWIW, if you are NOT in California, you can replace the rear cats with an inexpensive Magnaflow 53005 that will work just fine. You can buy it online for about $65 and any indie exhaust shop will weld it in for about half that.

Good luck.
 

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1999 e320 RWD
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7 Posts
Discussion Starter #11
Ok just updated my profile, thanks.

I'm in Alberta, Canada.

Interesting about the Magnaflow. I'm not sure if my cats to replace are rear or front.

I think I'll go with dealer for now (I want the car back asap and decrease chance of future problems/hassle), but next time the cat goes (hopefully in a long long time), I'll get aftermarket.

Funny that the left cat on my car was replaced in 2009. Now it's the right cat's turn. 280k kms on it.
 

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E320/E250 Bluetec Ford F350 6.7l
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Cats don't usually go bad on their own. I still would suspect you have/had fuel dump into the exhaust to cost that.
Do you do smog test in Alberta?
 

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1999 e320 RWD
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Discussion Starter #13
Alberta does not seem to have smog testing. But Ontario does. I might move to Ontario one day.

So you're saying there might be a problem behind the cats going bad, and it's not just wear and tear? I did ask the dealer about that btw, they didn't have an answer, except to say well my car is '20 years old' (it's 12 years old lol!), so it's just old stuff wearing out...
 

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E320/E250 Bluetec Ford F350 6.7l
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cats usually burn out, not wear out.
So yes, IMHO they could be the result, not the initial problem.
You should find "carburetor shop" who could run the engine test for optimal performance, or you can start DIY by putting new plugs, MAF and O2 sensors.
Doing those things you will get your money back on fuel savings, so no reason to hold on them if they are due.
 

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1999 e320 RWD
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7 Posts
Discussion Starter #15
Ok thanks. I will check on that.

I did replace the spark plugs 4 months ago, the old ones were there beyond the time they were due I believe, so that may have contributed.
 

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2005 ML500, 1999 C230 KOMPRESSOR, 1993 300E, 1964 220SE, 1994 E320, 2001 E320 4MATIC, 1991 380SEL
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47 Posts
A clogged Catalytic Converter can cause a misfire!
 
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