94 E420 - Code 11 on Pin 7 (EA/CC/ISC Module) - PeachParts Mercedes-Benz Forum

wjm · #1 01-07-2008, 11:24 PM

Folks,

Started my car today and it started running rough and giving off that rotten egg smell. Not sure if this weird 60 degree weather here in the midwest has anything to do with it or not. Drove it around the block once then decided to park it and investigate. I did notice that all of the gauges worked except for the speedometer. It seemed to be stuck on 0 while driving, then it kicked right up to 20mph after a bit.

I pulled codes and got the following:

Pin #7 (EA/CC/ISC Module), I got code 11.
Pin #30 (SRS Control Module), I got code 8.

No codes from any other system.

Any clues what to look at? Could I have a misfire or something?

2 things...
1... I recently had the car detailed (including engine). Not sure if that's relevant. It drove well for 2 days afterwards.
2... The original wiring harness was replaced in 1/2001

Larry Delor · #2 01-07-2008, 11:32 PM

Not looking at the codes, but just reading that you had the car detailed, makes me wonder if any of that silicone engine spray stuff was used. It'd been known to be unkind to mass air flow meters. Fortunately, there is a cleaner for them.

Check JimF's page for info on codes and the [MAF]cleaner.

ok...just went and looked at the codes myself. At first glance, your battery or alternator/voltage regulator seems suspect. Grab a voltmeter and see what kind of voltage you are getting before, and after starting the car.

wjm · #3 01-08-2008, 12:18 AM

OK... so first thing would be to check the MAF. Any idea where it is in my 94 E420?

Also, I did a bunch of reading. Seems like someone disconnected their MAF (temporarily) and it made the car run better.... is that possible?

Also, someone mentioned cleaning the throttle body... any clues how to do that?

Thanks!

wjm · #4 01-08-2008, 11:29 AM

Found the MAF. Not sure, though, what to look at. Can see thin wires (all connected) through the screen.

Someone said that if the MAF was bad, then unplugging it would make the car run fine (at least temporarily). Well, that didn't seem to make a difference, so it's plugged in again.

If I get some MAF cleaner, how do I actually clean it? Where to I spray? Can I spray while on the vehicle? If not, how does it come off?

Also... the ETA... where is it and how do I tell if it's problematic?

JimF · #5 01-08-2008, 11:31 AM

Willy, remove the air cleaner and it's the "thing" w/ the 'screen'!

If they used silicone I recommend that you remove it asap. It will make a mess on the hot-wire sensor (MAF) that your car has. The good news is that it can be cleaned; check MENU#4a.

You don't have to clean the ETA since I don't see that there's any codes that directly affect the ETA.

wjm · #6 01-08-2008, 11:35 AM

Hey Jim... LONG LONG time no talk! :0 Hope all is well!

Yea, we cross-posted... but I just found it. Did TONS of reading last night, including your site and the MENU#4a text.

Can I clean the MAF while it's on the car? Do I just spray the wires right in the middle?

Thanks!

JimF · #7 01-08-2008, 11:42 AM

Doing ok Willy, hope you are too!

You CAN clean on the car but it's not as good as taking it off; if it's contaminated, then you need a lot of 'chemical' to clean and that will make the car very hard to start and run until it burns off.

So it's best to remove it . . . there's a large hose clamp that holds it in the 'rubber' base that mounts on top of the ETA. Loosen the clamp and the MAF will come out. However, if it's not been removed previously, it will be a bit difficult; use a small flat blade to work it loose.

wjm · #8 01-08-2008, 12:06 PM

Quote:

Originally Posted by JimF

So it's best to remove it . . . there's a large hose clamp that holds it in the 'rubber' base that mounts on top of the ETA. Loosen the clamp and the MAF will come out. However, if it's not been removed previously, it will be a bit difficult; use a small flat blade to work it loose.

Yup... doing ok.

I can move the MAF a bit (clockwise/counterclockwise). I'll figure out how to take it out.

I'll get some MAF cleaner. When I do... exactly what am I spraying at? Then, do I just spray it and let it sit? If so, how long?

Also, while it's out... anything else I should clean?

Willy

wjm · #9 01-08-2008, 02:52 PM

OK... did a better look and found the clamp holding the MAF.

The clamp screw is on the front side of the vehicle pointing directly to the passenger side of the engine. It will be a real PITA to get to.

Any thoughts? Anyone ever spray the MAF while it was on the car? Of course, I would remove the connector first.

JimF · #10 01-08-2008, 04:03 PM

Yes, it is!! I use an universal joint so that that it can mate properly.

You can spray it on the engine but if it's badly contaminated, it will take a lot of cleaner and that will make the car start and run very badly.

Larry Delor · #11 01-08-2008, 05:56 PM

The spring clip retainer (for the mesh) can be removed for closer access to the thin wires. I sprayed the heck out of mine, but to no avail.
I used a utility knife to get behind the clip, so I could maneuver it out of there.

wjm · #12 01-08-2008, 11:03 PM

Quote:

Originally Posted by Larry Delor

The spring clip retainer (for the mesh) can be removed for closer access to the thin wires. I sprayed the heck out of mine, but to no avail.
I used a utility knife to get behind the clip, so I could maneuver it out of there.

Spring clip? I guess I'll have to look closer!

Anyway, since I'm not 100% sure that the problem is the MAF, I'm going to have the car towed to my mechanic and have him look at it. I told him I suspect the MAF... and he agreed, so he'll take it off and clean it for me. We'll see what happens after that.

Willy

JimF · #13 01-09-2008, 12:44 AM

Quote:

Originally Posted by wjm

Anyway, since I'm not 100% sure that the problem is the MAF, I'm going to have the car towed to my mechanic and have him look at it. I told him I suspect the MAF... and he agreed, so he'll take it off and clean it for me. We'll see what happens after that.

Willy

. . discretion is the better part of valor . . . .

wjm · #14 01-09-2008, 01:30 AM

Quote:

Originally Posted by JimF

. . discretion is the better part of valor . . . .

Sure is!

Still, how does one know if a MAF is bad? Is there a way for a mechanic (or a mechanic wannabe) to actually test these things?

If the issue still continues after a good cleaning, what have we learned?

Again, this car has been absolutely rock solid for the the entire 7 years I've owned it. The only thing I did between the time I got the car back from the detailer and when the problem started was to move the car up the driveway. The symptoms I'm seeing didn't start to happen until 4 days or so after I got the car back.

What else would there be to check? I still have no check engine light.

Larry... somehow I missed your comment about voltage. I'll check battery voltage before and after starting car.

JimF · #15 01-09-2008, 01:53 AM

Quote:

Originally Posted by wjm

Still, how does one know if a MAF is bad? Is there a way for a mechanic (or a mechanic wannabe) to actually test these things?

If the issue still continues after a good cleaning, what have we learned?

The MAF is clean if it works properly. MENU#4a shows the air-flow readings before and after using an AST Retreiver that can show live-data. That's about the best way (and easiest) that I know.

Quote:

Originally Posted by wjm

The only thing I did between the time I got the car back from the detailer and when the problem started was to move the car up the driveway. The symptoms I'm seeing didn't start to happen until 4 days or so after I got the car back.

If he used a silicone product . . . you NEED to find out what was used . . . and if so, make sure you throughly remove all of the silicone before cleaning (or replacing) the MAF otherwise the new one will be contaminated again.

When I did that PLUS I used K&N filters (MAF was also oil contaminated), I literally took the complete air management system apart and cleaned it. . . . even the INLET tubes! Don't forget them.

So I ditched my K&Ns and 'scrubbed' the MAF and cleaned the air-system . . the proof of a suceesful 'job' was on my last fillup . . just under 16mpg city. Doesn't sound like much but that's the best it's been in a couple of years . . . even with the 'big-tires' (MENU#32).