Testing plug wires & plug connectors question - PeachParts Mercedes-Benz Forum

haasman · #1 02-09-2003, 12:17 AM

I did a search through several threads. I want to test the plug wires and resistor plug connectors on the 190E.

I reas where the plug connectors should be 5K ohms and the wires themselves maybe 1K. Is this correct?

Would it make sense then if I test from the plug to the cap I should get 6k ohms?

I also found the good tip to wiggle each plug wire looking for broken or paritally broken wires.

Any other good tips?

Haasman

John Plut · #2 02-09-2003, 01:00 AM

I'm not sure about your 190E but my 260e and 300e have resistor connectors that are about 1k ohm (if I remember correctly). I think the proper resisitance is printed right on the metal part of the OEM connectors.

The plug wires on my cars are solid copper. The correct resistance should be 0 ohms for copper wires. They rarely fail except that the insulation could break down and cause arcing.

haasman · #3 02-09-2003, 01:02 AM

Thanks.

It seems the wires are OEM Benz. Would they also have the same value?

Haasman

ILUVMILS · #4 02-09-2003, 08:14 AM

The old rule of thumb for plug wires is 1K ohm per foot. I've found that it is usually less though. The suppressor will have the resistance stamped on it.

haasman · #5 02-09-2003, 09:03 PM

So if a wire is lower than 1k or higher .... then they should be replaced.

Same for the connectors, +/-5k?

Thanks,

Haasman

ILUVMILS · #6 02-11-2003, 05:53 PM

It's been my experience that when wires age, the resistance goes up. Way up! Same goes for the suppressors. I've never seen a wire or suppressor with low resistance.

haasman · #7 02-11-2003, 08:20 PM

That is helpful. I am simply checking out the wires and connectors on the old 190 and I wanted to be sure how to properly evaluate them.

Any ranges or limits?

Haasman

ILUVMILS · #8 02-11-2003, 09:02 PM

If it were me, I'd look more closely at the suppressors than the wires. I've seen a lot more bad suppressors than wires. As a tech I don't normally check the actual resistance of these components unless the symptom/complaint warrants it, so I can't say what the acceptable range is. What I do know however, is that if there is a problem with wires/suppressors, you'll have a definite engine performance problem. Usually, you'll have a dead miss on acceleration or an intermittent miss at idle. The symptoms are unmistakable. It's completely different than a fuel injection problem, for the most part. If you find that you have a bad suppressor or wire, check the cap and rotor as well(I'm sure you will). The higher voltage needed to overcome the increased resistance can damage these parts as well. Keep us posted.

haasman · #9 02-11-2003, 09:10 PM

ILUVMILS and everyone, thanks for the great tips. The 190 does have a small miss that seems to be more pronounced when cold and is *almost* gone when warm.

I will start with the basics: replace the (Autolite!) plugs with Bosch ones, check the cap and rotor, and of course, check the resistance on each connector separately and the wires ...

It may be this weekend before I can get to it, but I'll post back what I find.

Thanks again