Spark Plugs for BMW M54B30 on LPG

[Morat]

Hello,
I think I'm about to replace the spark plugs in the E46 330i. It has recently developed a bit of a misfire when cold (petrol and LPG) and I've been advised that the plugs are an early suspect. Now, the car is going in to visit an expert tomorrow - but if he asks about plugs should we go for standard or something slightly hotter?
Apparently, this is the standard plug:
http://www.turnermotorsport.com/p-1709- ... plugs.aspx

I've no idea how long the current plugs have been in there.... it may well be that they're just old and knackered (one sympathises) but I thought now would be the time to think about an upgrade if required.
Thanks!

[classicswede]

Try BKR7E - a lot cheaper option

[Morat]

Ahh, I am partial to a standard NGK spark plug. I use a BPR6ES in my E30 with great results.
So, are the OEM style plugs unsuited to LPG, being platinum?
thanks again
Morat

[classicswede]

Platinum plugs often break down very quickly on LPG and in my opinion (and NGK recommendations) are best not used with LPG. You are better off with either a standard or Iridium plug.

You could use the same BKR6ES plugs but I prefer to 1 grade higher heat range and it will do no harm with LPG.

[andy evans autogas]

The plugs recommended for your car are NGK. BKR6EQUP I would strongly recommend you use these plugs . Providing the LPG system has been fitted and tuned correctly ... Remember Make the system fit the car Not the car fit the system !!!!

[hardcorepit80]

The plugs recommended for your car are NGK. BKR6EQUP I would strongly recommend you use these plugs . Providing the LPG system has been fitted and tuned correctly ... Remember Make the system fit the car Not the car fit the system !!!!

Agree, I use standard plugs for the same engine, no problems at all.

[Morat]

When you say "standard plugs" do you mean the platinum ones recommended for normal petrol running or "Standard" as in "non platinum"?
My head is starting to spin!

[andy evans autogas]

Always use what the manufacturer recommends but if they recommend anything other than NGK then fit the NGK equivalent ....

[classicswede]

There is no problem with optimising your spark plug choice for running on LPG. Petrol and LPG are not the same type of fuel and do not burn the same. While is possible to keep the original plug type fitted there is no reason not to choose a plug that will perform better with LPG


NGK the spark plug specialists recommend not to use platinum plugs with lpg

No factory fit conversion has platinum plugs

For example the plug number for a Volvo Bi-fuel is basic plug as where the petrol version is either platinum or 3 prong depending on engine type.

[Morat]

OK, that makes sense - thank you!
And I'm pleased to report that the poor running was indeed solved by replacement plugs. Sadly the garage (who are fantastic with BMWs) don't know anything about LPG so they replaced like for like. Next time I'll go with iridium or copper.

The mechanic was confused by the fouling on the plug, he said it wasn't what he'd expect from a normal petrol engine so he did suspect that the LPG was involved. I've asked him to leave some of the plugs in the car so I can post up a pic when I get the car back.

[325i]

Ive gone for NGK BKR6EIX which are the Iridium upgrade from BKR6EQUP. Im having them fitted this weekend so will report back.

[bmw330lpg]

i have the exact same car and had bkr6equp in from day one....i have just started to get a mis-fire so its a plug (been in 5yrs) and lpg filter change (been in 2 years)

[rossko]

The mechanic was confused by the fouling on the plug, he said it wasn't what he'd expect from a normal petrol engine so he did suspect that the LPG was involved.

Prseumably you do drive around on LPG mostly, so yes the plugs will refelect that. The kind of perfectly normal deposits you get on plugs do look different to what you get with petrol.