I was wondering why my recently acquired [and recently tuned up] 1989 300E was idling poorly and had next to no power [driving around the block was an expedition].

Over the past few weekends, I've checked for vacuum leaks, electrical gremlins [the infamous OVP relay] and not come up with anything obvious.

I decided to look at the spark plugs - and I discovered the main reason the engine seemed to be running on two cylinders is that is was. Four of the leads had wiggled loose, and could be pushed in quite a distance before feeling the threads on the plugs engage in the sockets.

The car runs much better on six cylinders, but after a short test ride [30 miles or so - the odometer is strictly decorative] I noticed the idle was rougher, and there was hesitation starting off from a stop. After the engine cooled, I checked and the number 2 and 4 wires were loose again.

Ignition wires don't last forever and have even shorter life spans if they get abused. I would say that you are due for a new set of wires, there is no sense in trying to get more life out of them. After you install the new wires, always treat them very gently, (and try to fuss with them as little as possible) When you do have to pull them off a spark plug, do it very gently. There is a special tool available which makes removing the lead from the plug easy and is gentle on the lead at the same time.

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Junqueyardjim
Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important. C.S. Lewis



1983 Mercedes W123 240D 4 Speed 285,000 on the road with a 617 turbo, beautiful butter yellow, license plate # 83 240D INDIANA

2003 Jaguar Type X, AWD. beautiful, good mileage,
Mom's car, but I won't let her drive it!

The trouble here is that they are new wires [new plugs, wires, coil & rotor]. I don't know who the manufacturer was - need to check the invoice from the shop. [and next time do work like this myself].

If they are new, then I would look at them very carefully and see if perhaps with a needle nose pliers, see if you can get into that rubber cup that slips over the plug and try to pinch the metal end to fit the plug tighter. The connector at the end of the wire would have to be bent or broken.

__________________
Junqueyardjim
Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important. C.S. Lewis



1983 Mercedes W123 240D 4 Speed 285,000 on the road with a 617 turbo, beautiful butter yellow, license plate # 83 240D INDIANA

2003 Jaguar Type X, AWD. beautiful, good mileage,
Mom's car, but I won't let her drive it!

dlevitt, what do you mean by "before feeling the threads on the plugs engage in the sockets"? The threaded caps on Bosch spark plugs should remain in place. If the previous owner removed the caps no wonder the ignition wires come loose. If that's the case I recommend replacing the spark plugs. Use dielectric grease on the rubber to facilitate removal from the spark plug porcelain.

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Fred Hoelzle

The sockets on the wires should "click" firmly into the plug ends. If you don't get the click, they're not on securely. Put some dielectric grease on either the wire ends or the plugs, then push them firmly on. Then, just to check, pull them off and see how easily they come off. (Be careful not to torque them too much, that'll crack them too.)