Slow Guy

I've just finished replacing all 12 plugs. The 60k service was supposidly performed by a Porsche dealer in AZ apx. 5k mi. ago. From looking at the plugs I do believe it was done at that time (and they got all 12 !).

My question is, the plugs I took out were Beru R6 428 (2 electrode) and the plugs I ordered/installed were Bosch FR5 DTC (3 electrode). The Workshop Manual calls for the Bosch 5's or 6's or the Beru 14 FR - 5 DTU (are these 2 or 3 electrode?). Has there been a change in Porsche's recommendation for the spark plugs or are 2 / 3 electrode plugs fully interchangable?

I did check the gap on the old plugs and they were all over the map, some as narrow as <.6mm to .9mm! I did have to adjust the gap on a few of the new plugs as there some that were out too.

So, what are the latest recommendations for spark plugs from Porsche?

(I did a search on spark plugs first, a lot of threads came back but none I could find addressing this)

Steve Weiner-Rennsport Systems

Bill:

First, trhe FR5DTC's are a FAR better plug than those infernal Berus's so that a good move,...

Porsche (and other manufacturers) specify multi-electrode plugs simply for durability & longer life. These things last longer and help ensure that the car remains smog-complaint over longer periods of time. No direct performance gains.

pcar964

Thanks for the info Steve - is there a reason you refer to the Beru plugs as "infernal?" Is it simply because they don't last as long as the newer multi-electrode plugs, or is it because they're actually poor quality?

Thanks

Slow Guy

Thanks Steve. I wasn't really trying to get a performance gain out of this task though I hope having all plugs w/ consistant gaps may help some. I also wanted to start a baseline for maintenance going forward and to know that all 12 plugs had in fact been replaced.

Thanks again.

Jeff96-993

Yes, please explain why Beru's are not good... I've heard that before but never an explanation on why.

tj90

Instead of the multi-electrode approach, seems like some plug manufaturers have gone to Iridium. I just installed Denso iridium long life plugs into my SUV - They have iridium in BOTH the center and ground electrode which almost eliminates wear problems (changing gaps). I'm wondering if there is an iridium option for 993?. Before I knew about iridium, I recently changed to FR5 BOSCH so I wont have a chance to try iridium in the 993 for hopefully a long time.

pcar964

Interesting stuff - we need a plug expert here to set the record straight.

Travis

Just finished putting 12 Berus in as part of the 60K (plus new wires). The previous set in were Bosch of the same heat range.

The Bosch plugs were worn after 30K and the gaps were larger than the factory 0.7mm, however, the color was good on all the plugs (light brown) and no oily or wet plugs.

I too would be interested to know what makes the Bosch the preferred plug over the Beru brand. Is it brand preference or something more? I'm guessing something more.

-travis

Steve Weiner-Rennsport Systems

In my experience, Beru's not only failed at a greater rate but they caused misfires. Personally speaking, I think their overall QC is deplorable.

TroyN

There are Denso Iridiums for the 993. I got some from Automotion. Only had them for a thousan miles or so, but no issues (knock on wood).

geolab

I changed mine two weeks ago. Honestly did not touch gaps and just saw that they came
with a 0.8mm gap FR5 DTC (written on box). Would that make a difference with the factory 0.7mm recommendation? I am the cap. person to unmount all and regap if necessary.

Slow Guy

Spec in the workshop man. is .7mm + .1MM (notice no - .1mm so it's .7 - .8mm IOW). If you rem/rep get new washers first.

Geolab, I was hoping you would post the latest Porsche Tech Bulletin for us. You seem to have better access to that info than anyone.

tj90

I just checked:
http://sparkplugs.com/more_info.asp?...63002&pid=9673

It looks like the Denso Iridiums you got are IK20s. These DO NOT have the iridium ground electrode so they wont last quite as long as the long life version but you should be good for 60k miles (and probably longer).

Also note that they are gapped 044" so make sure to adjust before installing.

I wish I installed these instead (Of course, they are $11 each so its more $$).

Travis

Thanks Steve, appreciate the warning on the Berus. Next time, I'll put Bosch plugs back in.

I'll keep an ear on the motor to hear if I get any misfires. So far, the idle feels or sounds a bit smoother than before the plug change. Time will tell.

After doing the plug change for the first time, I don't have nearly the hesistation to dive in and do it again...Just not right away, please.

-travis

P-daddy

Reviving this older thread....
Does anyone use plugs other than Beru or Bosch? I'm going to do valve covers and planning on putting on some Bosch plugs while I'm there. Probably way too early to change at 46K miles but what the heck.