After making a run last night to the grocery store in my smooth running 1991 190e...this morning I started it up with a pronounced misfire up to about 2000rpm where everything smooths out.

I noticed the back plug lead was loose so I removed it, cleaned it and put it back on...still a misfire

Replaced the spark plug thinking that the loose plug lead might have damaged the spark plug...still a misfire

The spark plug wires and caps are at least 10+ years old... so perhaps the loose one needs replaced.

Two quick questions for MB World readers:

Is it possible to clean the spark plug caps with vinegar to remove oxidation?

Should I just replace the spark plug wires and is that something an oil changer like me can do?

Happy 4th to our US MB 190 owners!

 

Found the only pair of Autolite cables in Columbus...put them on this morning and car runs great!

Still had to fiddle w the plastic cable routing harness that presses in to the cylinder head...will try to refit that in the morning...

 

BTW the Pelican Parts how to's are great!

 

Seriously, if one lead went replace the lot, make sure you use OEM bosch with the metal caps, and do the dizzy cap and rotor button. And plugs. Should be replaced every couple of years really, but I get they're expensive, over here like you wouldn't believe, just a dizzy cap is 150 bucks, you're looking at a cool 500 for the lot but all top shelf OEM or better and a million headaches saved.
Solved a lot of little weird running problems with mine early on when I just bit the bullet and replaced all those. And the same hills I was losing speed going up, well it started holding speed going up, just from new dizzy, rotor, leads, plugs. Now with a cam/exhaust upgrade it gains speed going up those hills but that's another story.

That plastic plug lead cap on the valve cover, damn mechanic broke the clips changing the cam. It has slots in the top for a small screwdriver to remove it without breaking the clips, but he must've tried ripping it off from the bottom (exhaust side) instead of top (intake side), and you break the clips that way.
It's fiddly to put back on, but patience is the primary key, not a trick, just patience until you get the juggle of lining up the plug leads with one hand and clipping the cap over them with the other...


just a reiteration, being as I'm all about power on the ground, I checked out everything available on leads and there are a lot of claims with a lot of variations but the OEM metal plug bosch ones, in test figures stacks up to track quality. Actually pretty much all OEM gear on a 190 is track quality, I kid you not, the piston kit for a Formula-3800 open wheeler racecar doesn't have weights and tolerances as fine and balanced as a stock Merc M102 or M103 motor, our engines, I compared them personally. Tuning is why they perform like shopping trolleys, not quality or grade of shelf equipment, not by a longshot. At every turn, trust me, go OEM unless you have specific, researched and qualified reason not to, and it'll be better than any alternative all the way to professional racing. The bosch OEM plug leads are awesome mate as in can't really be improved on, aftermarket ones are hit or miss and full of gimmicks. Believe me I'm all about squeezing every last horsepower an M103 has in it just to keep up with modern traffic and still feel fun and fast, if there was something better I'd use it. And just about every time I hunt into an upgrade, aside from tuning changes, for actual parts replacement OEM keeps stacking up miles ahead of anything else by far.

 

Vanir...thanks for the steer! Had the distributor replaced but not the plug wires several months back...silly me! With the new wires there is so much more power!

That's some 190 you have!

 

Picking up a 983 M103 3.0 motor next week hopefully, have a racebuilder lined up to do some headwork, just a shave and valve job, stock already flows pretty fantastic. Bottom ends are already bulletproof and don't need work or balancing for race application. My cam has a full 1mm valve lift increase and a little more overlap (hence the head shave, cam overlap drops compression so you up it in the build to compensate), and finally the kjet is getting a rebuild/retune for enrichment to suit the cam and general refreshing. Oh and a fabbed header set from another racebuilder up the road, might get another muffler too I don't like mine (has a midrange drone since the 63mm upgrade).

I often say I'm hoping for 230bhp but I'm being conservative because weekend warrior power claim are a bit blase. In truth I've a solid 250bhp target in the coming weeks.
Make a nice change for the ca.185bhp I'm putting out now...when it's running right.

But in reality my car looks a bit rough in person, needs paint. Slowly getting there, I've only had it a year.
Paid only a grand for it hey. That's cheap around here, even the 2.3 in good condition goes for 4-5, just a 2.0 goes for 3. Just a lucky buy.