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Discussion Starter #1
2001 E320 4-matic wagon, 76K miles. Codes are 300, 302, 303. Thats misfires all on the passenger side. I cleaned the MAF and the wife got a days drive before the codes came back, along with the shuddering that goes with cylinder shutdown.

I pulled the downstream O2 sensors because they were easy to reach. With the car on a ramp, the flow coming out the O2 bungs felt the same on both sides. Would I expect that for clogged cat?

Anybody know a less expensive MAF sensor for the W210? I have a Volkswagon sensor in my 540 and its fine.

I could use some adult supervision.
 

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If you want to check for cat restriction you need to attach pressure gauge before the cat. Read out pressure gauge on both sides and post results.
 

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Discussion Starter #3 (Edited)
I don't have an O2 thread to shraeder adapter to use for that. How much of a pressure differential would I expect to see? The pressure differential between the two O2 bungs seemed awfully close.

The MB info I accessed through my ALLdata subscription shows measurements of the O2 signal before and after the CAT, i.e. they're measuring the temperature. The claim is that a working CAT has a higher exit than inlet temperature.
 

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2001 E320 4-matic wagon, 76K miles. Codes are 300, 302, 303. Thats misfires all on the passenger side. I could use some adult supervision.
And no 301?
 

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Discussion Starter #5
Interesting, eh? I think the first time it might have set that one too. I think I will hook up the laptop and go for a drive around the neighborhood. The cost differential makes the MAF cheaper than getting new CAT welded in. Now I'm leaning towards a failing MAF. If the CAT was clogged wouldn't I get a CEL right away?
 

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Interesting, eh? I think the first time it might have set that one too. I think I will hook up the laptop and go for a drive around the neighborhood. The cost differential makes the MAF cheaper than getting new CAT welded in. Now I'm leaning towards a failing MAF. If the CAT was clogged wouldn't I get a CEL right away?
No PO301, no plugged cat.

I would visually check those two coils in the back on that side and make sure they are not covered in oil from a leaking valve cover.
 

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Discussion Starter #7
Update: I looked at the passenger side of the engine and its all dry. I went for a drive, got the coolant up to temp, ~5 min. Then I floored it and the CEL came on. I got home and read the codes:

P0100* Mass or Volume Air Flow Circuit Malfunction [Pending]
P0136* O2 Sensor Circuit Malfunction (Bank 1 Sensor 2)[Pending]
P0300 Random/Multiple Cylinder Misfire Detected
P0301 Cylinder 1 Misfire Detected
P0302 Cylinder 2 Misfire Detected
P0303 Cylinder 3 Misfire Detected

The 136 may be a carry over from when I ran the car with both Sensor 2s pulled, or maybe I got schmutz on it when it was out.

So the Passenger side CAT is plugged AND the MAF is toast? I'm confused.
 

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If it was me, I would break down and get a replacement genuine Bosch MAF, persoanlly a VW MAF is not necessarily the best way to go.

Do you use silicone spray in the engine compartment for any reason ? The reason I mention that is normal MAF life should be better than 70K, and you also mentioned a bad MAF in your BMW. For owner's that use silcone spray in their engine compartment, don't know silicone can be the death for MAF's.
 

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Discussion Starter #9
No silicone in the Merc. The PO put a DINAN filter kit in the BMW which has a K&N filter, so I'm stuck with the oil.

A bosch VW MAF has the same part number on the sensor element (F 00C 2G2 025), its the plastic housing thats different. Surely the sensors are interchangeable if the part numbers are identical.

If the MAF life is >70K, then the CAT should be longer too, no?
 

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What about plug wires?

I'm not an advocate of throwing parts at any particular problem, but in this case, I would suggest you consider new spark plug wires. Maybe you could find a set to borrow before purchasing, but after 10 years, the factory wires might be spent.

Mine started throwing similar codes 2 years ago (well, not the MAF code), and it was a new set of plug wires that did the trick.
 

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Discussion Starter #11
Are the wires swap-able between the two sides?
 

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You might want to check for a vacuum leak on the passenger's side to start...do you hear any faint hissing? (Hard to hear, I know)
 

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Sure, you can do a wire and/or coil swap - but aren't you really going uphill, especially since you got your new/updated code ? It's only your time to do the swap/switchout.

Vacuum leak ? Well, that would be very interesting. If you find that, please let the forum know..

On the MAF sensor, I understand your opinion. The VW swap does work for most, but understand that the sensor # is different, and the assembly # is different for the OE part.

It's due to counterfeiting/phony Bosch parts that Bosch stopped bringing in sensor only-for MB's.. the Bosch sensor-only has been knocked'off including molded Bosch item# by China for years.. it got so so bad, that even larger internet retail houses could not discern the true from the false..

As long as your are informed, you can do what you choose to do.. autopartsway.ca now understand this that their US web site sells Beck Arnely (China made) including the knock off Bosch sensor I mentioned (with Bosch part#) in the US

2001 Mercedes-Benz E320 search:W0133-1601180 in Canada - Canada 2001 Mercedes-Benz E320 search:W0133-1601180
 

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I got home and read the codes:

P0100* Mass or Volume Air Flow Circuit Malfunction [Pending]
P0136* O2 Sensor Circuit Malfunction (Bank 1 Sensor 2)[Pending]
P0300 Random/Multiple Cylinder Misfire Detected
P0301 Cylinder 1 Misfire Detected
P0302 Cylinder 2 Misfire Detected
P0303 Cylinder 3 Misfire Detected

The 136 may be a carry over from when I ran the car with both Sensor 2s pulled, or maybe I got schmutz on it when it was out.

So the Passenger side CAT is plugged AND the MAF is toast? I'm confused.
No sir, The MAF is only being allowed 1/2 the amount of air it normally would, because it can only get 1/2 the air out of the engine, (1 out of 2 cats plugged) and thus, throwing the light for a bad MAF.

The 1,2,3 misfire is because it cant get the spent exhaust gas out.

The o2 sensor would read correctly, if it had air flow across it.

So you found your problem, Plugged Cat.


Pending, means the part works, but will go out of design parameters (trying to get the car home) because it can not get good 02 sensor readings.


So that's, change the cat, clean the MAF, clear codes, drive. Should be no more codes. Like I said no 301, no plugged cat, since you have all three, you have a plugged cat.
 

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Discussion Starter #15 (Edited)
Well that was easy. Thank you. Can I assume its the down stream CAT, as per the DIY sticky, or is more diagnosis needed?

Also it turns out that the electronics can compensate for differences between the 025 and 032 sensors . While I have an 032 sensor in my BMW, i'm concerned that the clogged cat could cause blowback that would trash my good sensor were I too swap.
 

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Discussion Starter #16
Update. Got a magnaflow CAT for the passenger side secondary welded in at a local speed shop. I drove down with the downstream O2 sensor removed, so no codes en route. $225 CDN all in. Car is now a happy camper. I looked at the old CAT and the core was rolling around inside the shell, so I couldn't really see down the holes. Wasn't clear if it got broken free during the removal process, but I was starting to hear the CAT death rattle on my way to the shop. Not much blockage once its broken free though.

Thanks again to the list.
 

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Update. Car is now a happy camper. I looked at the old CAT and the core was rolling around inside the shell, so I couldn't really see down the holes. Wasn't clear if it got broken free during the removal process,
Nice, I commend you on sticking it out and fixing your own car! Good job!


MAF readings all good now? Back to normal?
 

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Discussion Starter #18
Not sure which readings I would be looking at. The CEL is off and no stumbles under WOT, no CEL. Bubkus. I gave the MAF a good spray down with throttle body specific spray cleaner, so unless its packing up also, I should be good to go. We'll see. My wife can ignore a lot when it comes to car malfunctions, but 3 cylinders shutting down is above her threshold.
 

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Not sure which readings I would be looking at. The CEL is off and no stumbles under WOT, no CEL. Bubkus. I gave the MAF a good spray down with throttle body specific spray cleaner, so unless its packing up also, I should be good to go. We'll see. My wife can ignore a lot when it comes to car malfunctions, but 3 cylinders shutting down is above her threshold.
No light, MAF is good.


I gives me some joy to see you guys fix your own car and not get screwed in the process.


Feel lucky, my wife just turns up the radio when there is a new noise. Hince the reason she gets a new Mercedes every couple of years. Does the same thing for check engine lights too. <-Don't know what that is about.


Imagine that, a Mercedes mechanics wife that cant keep a good car. AND, and I'm not fixing it! She has probably had 15-20 Mercedes over the years we have been married, I never turned a wrench on any of them. And they were almost garbage when she turned them in. Hell the 67 280 she got as a wedding gift, she had the trans stripped in 3 months.


Sorry to rant, but she dented the roll pan on my truck this morning.
 

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Discussion Starter #20
My wife knows that if she breaks it, it sits in the garage until I fix it. The only exception is rust. When she can't stand the rust, we get rid of the car. My e28 535 was 22 years old and her Volvo 850 turbo wagon was ~15 years old when they went.

Maybe if you DID keep fixing her car she'd take better care of it.
 
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