engine miss-firing, easy fix (scary)

sammyg2 · 03-22-2004, 11:09 AM

I was out playing with hte turbo SC today and it started to run a little rough. It was noticeable at idle and the sound just wasn't right and it was down on power a little.
After I got over the panic and stopped thinking I hurt the motor on that last run up to red line on boost,
I limped home ( 4 miles) trying to convince myself it was ignition related to one cylinder.
Sure enough, the number 5 spark plug lead had come loose from the spark plug and was only hitting once in a while. I reconnected it and the car runs fine again.
I have no idea if the problem was due to a mental obstruction (me not putting the wire back on right) or if it was the magnecor wire just coming loose from excesssive G-forces (LOL).

I'd bet money it was my fault, but has anyone else had a magnecor wire come off a spark plug?

I put about 25 miles on the engine since I re-installed it so the loose wire didn't happen all the sudden-like.

tsuter · 03-22-2004, 11:20 AM

Just think of all that fuel in the intake waiting to go "bang" if the wire jiggled back on ... especially with no pop valve in your air box anymore!! Now that's scary!

I have ss braided OEM wires and they haven't come off but I have tried to run them incorrectly sequenced at the rotor cap. Bang, bang! That didn't work too well!

Early_S_Man · 03-22-2004, 11:21 AM

Sam,

The poor fit and coming loose of Magnecore wires has been reported before on Pelican. My suggestion is to get some Nylon strain reliefs ... the ones shaped like capital letter 'P' ... and fashion some way to secure them to the valve covers. I don't think the 906-style retainers will work with the Magnecore ends, but that might be a start ...

Neilk · 03-22-2004, 11:43 AM

Happened to me as well with Magnecors.

ubiquity0 · 03-22-2004, 12:22 PM

Weird- I had the exact same problem this weekend!

vash · vash's Garage

a well known mechanic on this board told me the same thing. the magnacors just dont have that nice "pop" when pushed onto the plug.

kstylianos · 03-22-2004, 12:56 PM

Quote:

I have no idea if the problem was due to a mental obstruction (me not putting the wire back on right) or if it was the magnecor wire just coming loose from excesssive G-forces (LOL).

Sammy,

I had the exact same problem on the track last month. Coming out of a turn I noticed the SC was down on power and missing. Into the paddock we come and, like you, noticed the #5 magnecor lead came off the plug. Put it back on and its been fine since. I have been checking them regularly as a pre track routine. BTW: thinking a little pressure from a pair of needle nose will tighten up the clip.

sammyg2 · 03-22-2004, 12:57 PM

Hmmm, I really like the magnecors, I'll give em one more chance. If it happens again I'll toss em.
I have a good set of used OEM wires in the garage, but one beru plug connector is ka-plooy (technical term for infinite resistance).
All I need is one connector to fix em. hint hint hint

It's the kind where the wire screws into the long skinny connector, in other words the connector has female threads.

vash · vash's Garage

Quote:

Originally posted by sammyg2
Hmmm, I really like the magnecors, I'll give em one more chance. If it happens again I'll toss em.
I have a good set of used OEM wires in the garage, but one beru plug connector is ka-plooy (technical term for infinite resistance).
All I need is one connector to fix em. hint hint hint

It's the kind where the wire screws into the long skinny connector, in other words the connector has female threads.

$20 dollars at pelican. if you go that route, you may as well get all new wires from someone selling bulk. and then get a benz mechanic to put the crimp on ends put on. superman, said a motorcycle shop usually sells bulk 7mm wire. weird how it always seem to be #5 cylinder. my beru @ #5 cylinder went to infinity....goddamn conspiracy!

Superman · 03-22-2004, 01:20 PM

Cliff, I did not know that the, ahem, well-known mechanic has commented on the Magnecore snap weakness. I can only assume this was the man-of-few-words gentleman. At any rate, I do know that the Beru connectors do not have a wimpy snap problem. It's pretty easy for me to tell when they have made their connection, considering I nearly have to lean on them with my shoulder to get them seated.

And yep, a Benz mechanic can easily install those screw tips onto bulk lengths of 7mm wire. From that point, assembling a new set of wires might take a half-hour, max, if you take the time to trim the wire to the EXACT length and appearance you want.

vash · vash's Garage

yea, i called him a few weeks ago. once he got going, he was a friggen wealth of info. i needed to know where to find the wire. i like the fact that you can take the wires apart and test the various sections on the beru's.

sammyg2 · 03-22-2004, 01:46 PM

Well I jumped the gun blaming the magnecor.
I went for another spin and it happened again. Now I'm pissed. I got back home and pulled the plug, sure enough the little metal screw thingy on the spark plug had come off and was stuck in the end of the plug wire connector. I tightened the living snot out of the metal fitting and re-installed everything, the magnecor connector snapped on just like it was supposed to and feels good now. It takes a good bit of tugging to get the wire off the plug, I don't think it will come off again by itself. As soon as everything cools off I'm going to check all of the plugs. Those upper valve covers get hot after they sit for a few minutes.
An engine's worst enemy is it's mechanic