Large Spark Plug Gap and New Ignition Wires
 

Hello. I recently changed the spark plugs on my 1989 260e with around 135,000miles and out of curiosity I checked the gap on the old plugs. I was quite surprised to find that almost all six of them had gaps around .052 and some upwards of .056. The new plugs were ordered from FastLane and I left them at the pre-gapped .032. Anyone know what the deal is with the huge gap on the old ones? Could that have been hurting performance significantly, and should I increase the gap on the new ones a little? The engine seemed to rumble a little just at idle with the old ones and still does a little with the new ones.
Second question - is it about time to replace the ignition wires? As far as I know, they are roughly 13years old with 135,000miles on them. Will replacing the wires have any positive effect on performance? I think I can get a set of the wires on eBay for around $80. Thanks for any help/info!

IMHO, if you have an idle problem with the plugs gapped at the recommended gap, it isn't the plugs.

As for the wires, I happened to damage one plug wire trying to get it off a '91 300E with only 50K on the clock. I ordered a new set from MB dealer Caliber and installed them. Apparently there were more problems than just that one wire. The new wires made a noticible improvement in fuel mileage despite no indication that I had any problems before changing them.

I recommend using Bosch original equipment wires no matter where you get them.

I've also said this before, get yourself a can of HD silicon spray and spray the insides of the boots of the plug wires and they will come off much easier. It also prevents inadvertant damage to the wires trying to get them off the plugs with anything other than the correct plug pliers.

I paid $134 for the MB wires from Caliber.