Hilux Spark Plugs

Original topic, click here - By 3RZ

I would recommend that you stay with resistor type spark plugs if specified by the manufacturer. It seems that the resistor inside the plug is used as part of the resistance of the driver circuit of the ECU in the newer ECU/EFI vehicles. (It was orginally introduced to suppress radio interference) Using non resistor plugs cause the drivers in the ECU to overheat and get damaged because of the lower resistance. This little lesson cost me R4400 compliments of Renault for a new ECU. I got the wrong alternative spark plug part no of a website and when the spares shop did not have the correct one's in stock used NGK BP6ES's instead of BKR6E or BKR6ES. An expensive mistake I will not make again.

From the NGK website:

http://www.ngkspark.com.au/bulletin_index.htm

THE INFLUENCE OF LPG

An engine converted from petrol to L.P.G. (liquefied petroleum gas) will cause a change in the spark plug operating conditions. Therefore, some consideration should be made on the type of spark plug being installed.

As L.P.G. has different properties to petrol it influences the spark plug operating temperature and required voltage. The extent of this influence can be seen when comparisons are made on spark plugs which were fitted in an engine using L.P.G. and petrol.

Typical results are as follows :

1. Spark Plug Temperature

Temperatures are higher with L.P.G.
compared to petrol. This occurs due
to L.P.G.'s reduced cooling effect.

2. Spark Plug Required Voltage

Required voltage increases with L.P.G.
because of the difference in the bonding
of gas particles between the two fuels.

Recommendation

To eliminate the influence of L.P.G. and to obtain optimum spark plug performance, NGK recommends:

-The use of a spark plug with one heat range colder (if possible) than that listed in the catalogue: eg, BPR6EFS-13 (L.P.G.) instead of BPR5EFS-13 (petrol) for VN 6 Cylinder Commodore.

AND

-The reduction of the electrode gap by 0.1 mm (which lowers the spark plug required voltage)

Here is an explanation of the spark plug heat range;

http://www.ngk.com/charglossary.asp?kw=Heat+range