Car is pinking, which of these is fuel octane adjuster? (pics) - PeachParts Mercedes-Benz Forum

pentoman · #1 07-13-2002, 04:12 PM

Well, for seemingly no reason at all, my 190e 4-cyl has suddenly started pinking (knocking) when using more than about 50% throttle, and more noticeably when warm. I'm using the same fuel I've used for the past year, so can't think why.

I have someone looking into it, but for now it's suggested I use higher octane fuel, or leaded fuel (I have no catalyst), and until I can do that, adjust the car to retard ignition therefore preventing pinking.

In the US you remove or adjust the R15 (?) resistor to adjust retard for the fuel's octane - in the UK & europe we apparently have a selector switch to adjust the ignition retard. Unfortunately I can't find it..

Passenger side under hood (Right hand drive car) - is the blue circle it, or just a diagnostic plug? What's the green circle.. doesn't seem to adjust.

Maybe blue thing? For the record, the green thing is the fuse for the OVP relay.

Blurred close-up of the blue thing, seems to have 'M4' and 'M5' written next to the slots, with a wire into the 'M5' slot, nothing into the others.

Drivers side, nothing of interest that I see

Nothing here?

And finally, what on earth are these? They are on driver and passenger sides - I've pulled this one apart for the photo.

Thanks for any help... I *really* need it!

JimSmith · #2 07-13-2002, 04:36 PM

pentoman,

On my Euro 190E 2.3-16 the thing you have circled in blue in the first photo is the unit. However, you are missing a little black cap with green lettering ("N" and "S" with numbers between them arranged like a watch face with the letters not quite diametrically opposed) that has an array of resistor circuits that go from the center pole to pins on the outer periphery (still under the cap). Looking at the socket in your car I see the arrangement is a little different, and yours may not be the same as mine. On my car you set the timing by aligning the "N" for normal gas, or "S" for super or high test gas, with one of the clips that hold the cap on. One spot has no resistor or connection (infinite resistance) for advancing the spark timing as far as it will go.

If you use really good gas does the problem go away? If not, you may have something else going on.

I hope this helps, Jim

stevebfl · #3 07-13-2002, 05:51 PM

First thing I notice is everything is on the wrong side, I bet that applies to the driver and passenger also (bg). The first picture is of a switchover valve (green) and the diagnostic socket (blue). A switchover valve is an electrically controlled vacuum switch.

In the other picture the red is probably the OVP and the blue I don't know except it might just be a connector rail the 5 and 4 refering to screw size.

The last open connector is of the type used for ABS sensors. It is a shielded connection so the signal inside is small and precious. Speed sensors such as ABS and crank shaft use such connections.

pentoman · #4 07-13-2002, 06:45 PM

Steve cheers for the info, interesting about the ABS signals - Jim says the blue thingy in the first pic is the switch I'm looking for, to adjust retard. Does it share a purpose as diagnostic too?

And no dammit, the driver and passenger are on the *correct* sides.. :p It's just the rest of Europe and the whole of America that got it wrong

later

stevebfl · #5 07-13-2002, 07:22 PM

Well I didn't want to say Jim was wrong, but it sure looks like the diagnsotic connector to me.

The device you want is similar looking except it has numbers and or letters instead of holes about the periphery. The diagnostic connector is just the end of a bunch of wires.

The piece you would be looking for (not saying it exists) would be basically black about as big around as one of our quarters and have resistors inside (you can't see this though). By unplugging it and turning the outer piece the resistance changes to the controller bringing up various timing maps.

JimSmith · #6 07-13-2002, 09:09 PM

pentoman and stevebfl,

While stevebfl may not say I was wrong, I will. If that is a dianostic plug, it is not the unit I was describing. The ingnition timing changing device is about the same size, and has a black cover with a bunch of male pin connectors sticking out the underside that engage a bunch of female sockets in the piece mounted on the fenderwell. It is not intended to have the cover come off, but it will come off if you pull it off. No damage in pulling it all the way off though.

The unit I was talking about is on the driver's side of the car. In the bulk of the world that is on the left side of the car, when seated inside looking forward. With everything on your car on the other side, perhaps this item is over there too.

I only see the adjustable timing unit on autos with factory emissions equipment early in the transition from leaded to unleaded fuel. Does yours require unleaded fuel? Other cars typically use a single resistor somewhere. It is possible your car does not have the adjustable unit, and your resistor is burned out.

I hope I did not screw things up too much with the misidentification of the diagnostic socket. Jim

pentoman · #7 07-16-2002, 07:18 AM

Well, I have looked, and browsed the Bosch Electronic Service Information CDs about the switch. I can't find it where it's supposed to be, so mine must be a car without it. I can't find any R-16 resistor either, and the pinking is getting worse.

I filled up with LRP - lead replacement petrol, for cars that don't run on unleaded (though mine's been fine on it for past 18 months) in the hope it would stop the knocking, but it hasn't, in fact the problem is getting worse.
Any help or ideas why this would happen?

I'm going to hook up to a diagnostic computer when I have the time, and see what I can uncover

later

Bazzman · #8 07-16-2002, 05:45 PM

Hey, don't worry about these guys saying everything's on the wrong side. What do they know? They even call the bonnet the HOOD. (bg)

Actually I had an 87 200 w124 and I think, though at my age God know's if I'm right, I believe the resistor thing discussed was on the ignition module, just to the left of the diagnostic socket.
You can just see it in your photo. I seem to recall it was a small round plug, about 10-12mm in size.

Just my tuppence worth.

Barry

E200 Wagon 1994 119k miles

BENZ-LGB · #9 07-16-2002, 06:19 PM

Pentoman:

If your car is pinging, under a light load, when it is warn outside, you may have a problem with carbon deposits. Try the Lubro-Molly valve cleaner product and see if that helps. A couple of cans may do the job. If your car is running hot, check the coolant/water ratio and make sure that it is no more than 50/50.

I have no opinion or advice on the items depicted on the photographs that you posted.

And yes, you guys on the other side of the pond have got it all backwards. Anyone who calls a car's hood a "bonnet," the trunk a "boot," an elevator a "lift" and a restroom a "toilet" has been eating way too many sweetbreads and drinking far too much warm ale.

Good luck in finding a solution to your pinging question.

pentoman · #10 07-17-2002, 10:28 AM

Thanks for the further help guys -
Well, the car doesn't run over 100 degrees ever, and only pings once it's running at its normal ~85 degrees. But the problem did first come on in hot weather - coincidence?

I do burn a heck of a lot of oil. Do you know how the carbon deposits on the valves causes pinging, or how the deposists are caused?

Barry - I see the ignition module, with 2 plugs. The larger is the Electronic Ignition Control Unit Plug, and the other is like the ABS plug in my final picture, so must be for some low voltage signal.
There's no resistors there, and no switch for the octane adjustment.

For the record, here's the resistances and positions as shown by Bosch's ESI CD, for anyone wanting to adjust or play who doesn't have the switch:

EZL EZL-ECE (no catalyst) EZL-KAT (catalyst cars)
1...........S.............................1....... = infinite resistance
2...........2.............................2....... = 2.4 kohms
3...........N.............................3....... = 1.3 kohms
4...........4.............................S....... = 750 ohms
5...........5.............................5....... = 470 ohms
6...........6.............................N....... = 220 ohms
7...........7.............................7....... = 0 ohms (short-circuit)

S = for Super-unleaded hi-octane fuel
P = Premiem fuel

On all switches the resistance values are the same, only the markings of numbers or S's and N's are different. With a catalyst if using Super fuel, you need 750 ohm R16 resistor or switch in 'S'. Without a catalyst you need no R16 resistor or switch in 'S'

later. and please keep helping..!

Bazzman · #11 07-17-2002, 01:10 PM

Hi Russ

sorry mate. Either my '87 was different or I've got it wrong.

I've looked at the Haynes manual too, and there's nowt there.

And hey guys, of course it's called a bonnet, not a hood.
I mean the engine has a head, so a bonnet goes on top of the head, right?
And a trunk is what goes in the boot.
Just don't get me started on Arse

Cheers Guys

Barry
E200 Wagon 1994 110K miles