divil

After owning my 951 for a little over a year I am changing the plugs, leads, distributor (cap & rotor) for the first time. It's been idling rough for the first few seconds on startup, and occasionally hesitating during acceleration around 2K rpm. I spotted some arcing from the plug leads, and indeed the insulation on all the old leads is looking pretty tired.

I haven't removed that many plugs, but I don't remember ever seeing this kind of variation in the colour of the insulators before. Do these plugs tell you anything interesting? I don't find the guides on Clark's on the Haynes manual all that useful as the pics in Haynes are black and white and the descriptions are vague.

These are ordered - cylinders 1-4, left to right. 4 is significantly darker than the others, with 2 being a lot lighter. The electrodes don't vary so much, but number 4 does seem a bit darker coloured than the others.

Also, all 4 were gapped around 1mm - which is more than the new ones (which were around 0.7 - 0.8 out of the box, as recommended by Clark's Garage)

ZR8ED

Sometimes it takes a closer look in the cyl bores, but this is how I see it.

1 ok
2 lean
3 ok
4 rich/fouled

xsbank

Have you done a run after you changed the wires etc?

divil

haha... no because I haven't been able to remove the coil cover to get the new coil lead on. It got dark while I was still fiddling with it so I'm going to finish that this evening when I get home.

StoogeMoe

I see them as

1 slightly less than beautiful
2 beautiful
3 ok
4 either a bit rich or burning some oil

Nothing serious by the looks of them. Definitely change the gap back to 0.7mm. 1mm is too big and may have contributed to your rough running. Definitely change your plug wires. I just went through this a couple of weeks ago.

HICKS

To remove the coil cover, undo the clip where the split is and pull up. Mine was stuck on too, you just gotta yank/twist it.

bordin34

Do you have pictures from the other side of the plug so you can see the color change on the strap.

morghen

1. ok
2. perfect
3. lean
4. ok but with a bit of oil (valve guide/seal?)

check the injectors for equal flow and the cyl4 valve

divil

Nope but I will take more pics and post them later.

I think I will have send the injectors away to witchhunter or one of those kind of places - that was recommended to me anyway before I removed the plugs. I am planning to change my fuel lines soon so I will do this at the same time.

Nobbi

Hey,

i own a 944S2 cabriolet and my plugs look the same because they become loose after est.5000Km. Number two is ideal, the other 3 are not torqued within spec. i guess.When you remove them from the head check for oil residue. If you find oil arround and your plugs look like Nr.4 torque them down to spec.
The engine is full alumnium so something arround 30Nm will be fine.
Get the right plugs TURBO= Bosch WR7 DC and replace them every 15000miles !

divil

Funny you should say that because I did think that they came out a bit too easily. I had forgotten that until you mentioned it...but my Haynes manual said they should be something like 20 ft/lbs, and because of that I was expecting the old ones to be tight, but in fact they were not. Using only the plug wrench that comes with the car (very short handle) they were very easy to break loose. Not loose exactly, but I certainly put the new ones in a a fair bit tighter than the old ones were.

Nobbi

Replace them when the engine is cold and you will find GOLD......

Nobbi