Dave Kost

I developed a miss on my 2.6 190e. Started to test the plug wires and on #1 and #4 no continuity. Any body know what the OHMs should read? I know the ignition is a system and all the components should match and the total resistance of the system is important to maintain. With that said I ordered a set of Mercedes plug wires.

Also, can the spark plug connector be replaced? I see that you can buy Beru connectors. Anyone know how they can be replaced?

BTW- The plugs are correct H8DCO.

Thanks,
Dave

190Efan

You might also want to check your distributor cap to make sure there's no moisture there. That can also cause a miss as can frayed wiring and dirty or corroded connections.

dolucasi

Hi Dave. The wires should read 1Kohm. The plugs are 0 Kohm, and the HT cable supposedly (never confirmed myself) measure another 1Kohm.

If you are measuring an open, most likely it is the plug socket. place the spark plug in there and measure from one end all the way to the plug tip, it should be 1Kohm.

I would strongly advise against buying the connectors and just crimping them on if that is the method to connect to the wires. That will not make a lasting connection.
I am in the electronics manufacturing business and crimped connections like that is the #1 failure rate for components. You will not find that in any other connector on the W201.
Now if one is asked to solder them on and you are good with the soldering iron I may change my position but I would never do that myself, even though I am handy with the iron.
I let the Bosch's and the Beru's in the industry worry about that....

Also even though my wires are still original, they do not last forever. If yours are also original it maybe time to replace them.

Best way is to replace the spark plug wires as a whole with the connector and all at once.

One last point I want to make, make sure the misses is ignition, sometimes the rpm's can have 50rpm jumps say from 750 to 700 ever now and then and that feels like a miss but it is not.

- Cheers!

Dave Kost

Thanks for the reply.

I may have pulled on the spark plug wire and pulled the wire from the spark plug connector-so I thought. So, I cut apart he #1 spark plug wire. The spark plug connector itself, has an open circuit. The spark plug wire screws into the SP connector. The wire to the boot has a resistance .2k OHm's. I cant under stand why there is an open circuit on the connector, unless there is i resistor inside to compensate /achieve 1k ohm's.
Ill post some pictures later today of the connector (Beru) I cut open.

I bought a Mercedes wire set but delivery is in a week.

Dave Kost

Here is the 1# cylinder spark plug wire I disassembled for testing.

Item 1 had a resistance of .2k Ohms.
Item 2 had a open circuit.

I tested 2 other spark plug wires that I did not disassemble and the both were open circuits.

Are these plugs wires good?



These where Beru wires.

dolucasi

Dave I corrected mis information in my previous post. Spark plugs are zero ohms (duh!). So tip to the other end of the connector should be 1Kohms.

That wire does not look bad to me visually but if you are not getting the desired resistance I suspect the tip connector or the wire is broken somewhere and at 10KVolts it is probably arcing through and barely working.

I am curious to find out if the dealership now sells Beru wires since Bosch appears to be out of that business too (like the spark plugs).

Dave Kost

Dolucasi,

The connector that attaches to the spark plug - #2 is open - no continuity. I tested another plug wire #4 it in to has no continuity. I don't recall were I bought these wires but they are only a year or so old.

The car is sluggish, a hard time reving past 4500 rpm.

I ordered two sets of plugs. Ill test the resistance before installing.

As a side note , I had a Porsche 912 that a cylinder would drop out after 15 minutes of driving. Tried everything to fix the problem and I mean everything . Turned out to be a bad spark plug wire. Apparently, there is a resistor in the spark plug connector that would short out, assumingely because of heat, and that cylinder would not fire. Im guessing there is a resistor in the Beru connector too.

So, can someone test the resistance of their plug wires along with the brand.

Thanks,

Dave Kost

Ok Tested all the sp wires. #1 and #4 no continuity. All others ~ 1K ohm's.

Called a Beru Distributor and they confirmed 1K ohm's on the wires. Also, there IS a resistor in the spark plug connector.

Oh well......

dolucasi

I think the 1Kohm spec includes whatever is in the plug connector. My Bosch spark plug wires measure 1.2Kohm from end to end including the connector. Just measured it.

bicylindrico

The cables should have no resistance as they are stranded stainless steel with no built in resistance. The only resistance should be in the suppressor end. The secondary ignition was designed to be rebuildable with the p[roper Beru crimping pliers

dolucasi

I assumed it would be better to put the resistor at the spark plug end instead of the other end by the distributor so that the current spikes in the spark plug wires can be suppressed.
That is what is accomplished by resistor plugs, so I thought. And for the HT wired from coil to distributor, I thought it would be best to be at the distributor side.