Thread: clean or replace PFR5G plugs?

Hi Paul

How many Km have they done. They look a bit worn and as there not ment to be regapped I would replace full set. I paid $92 delivered 6 or 7 months ago. Just my opinion but then who am I.

Gary

I can't really see the colour... if they are black thrash the engine for 50km and then pull the beggars out and check. If the insulators are a strongish brown colour chuck 'em as they have been running too hard. If there are flaky oil deposits, ping them off and reinsert. If they aren't misfiring what are you worrying for?

They look very oily and carboned up.. piston rings/valve stem seals? mixture issues? You could give them a touch up with a sand blaster using glass beads... good excuse to buy more tools probably cheaper to buy new plugs!
NKG plugs suitable for P38 from British Parts UK ..$3.23 each.... I paid around $18 EACH for the superduper NKG ones several yrs ago... I don't know that they are worth it...

They look pretty dirty too me.
Are the plugs hot enough?
When i pull my plugs they are pretty much spotless, just worn.
What fuel do you use?

I only use United Plus ulp (ethanol 10%) it seems to burn beautifully.
You seem keen on fiddling with the 38, put them back in and run a tank of premium or the united fuel through it and see if they come out any cleaner.

They look like pretty normal platinum plugs in a non O2 sensor car to me .

They should be good for 100KK so you are wasting money by replacing them . If you want to replace them just use normal plugs , if you really like to replace plugs every 20-30Kk . The only reason they demand platinum is to go 100KK to satisfy USA ( and later Australian) emission standards that nothing be touched for 100KK.

Do not try to regap them or odds are you will break the centre electrode as it is very fragile.The makers also say do not clean them with abrasives.
If it is not missing , all is as it should be except that the car has not been on the highway enough.
This answer is assuming you have a pre 2000 GEMS and not a Thor, as I understand a Thor needs the platinum plugs to give feedback to the ECU on whether the cylinder has missed.
REgards Philip A

Phillip
Tell us more on this feedback issue.
I've just replaced my platinums with standard plugs, Britpart No. ERR3799. These were supplied from UK as part of a tune up kit for a 1999 Thor engined 4.6.
It seems to be going fine at the moment, but obviously I don't want any problems with the ECU.

I'd much prefer to replace the plugs regularly, say 10k, if only to be able to get the buggers out. The platinums in mime were so tight I was scared of stripping the threads on nearly each one.


PS: Check the markets section if anyone wants to buy a good P38!

This answer is assuming you have a pre 2000 GEMS and not a Thor, as I understand a Thor needs the platinum plugs to give feedback to the ECU on whether the cylinder has missed.

I recall reading several years ago that the Motronic ECU balances the engine by calculating the rev drop on each cylinder and that it also reads the resistance of each plug to determine whether the cylinder has fired properly. The actual balance of the engine components is less accurate/precise because it can do this.
It was said at the time that only specific plugs could be used in the engine because of this requirement.
This is one article.
Untitled Document

I do not know how true it is , so I guess you must suck it and see.
Regards Philip A

Thanks gents. It is a 1999 Thor engine. I am going to put the plugs back in and run a couple of tanks of hi octane fuel through it to see if it makes a difference. I usually alternate between normal unleaded and 95 octane. I didn't think the United ethanol blend was suitable for the Rover V8 so have avoided it.
Cheers, Paul.