I have 1986 mazda rx-7 (european model). It doesnt have advance ignition system with crank angle sensor but it have ignition coils and distributor instead.

So i have at the moment inside spark plugs BRU9EQ, BRU7EQ

Bur in training manual it is writen that BR9ET,BR10ET spark plugs should be used, when i double checked on UK NGK web page is writen that only 4 plugs BR9ET should be used in 1986-87 RX-7 EU model.

Now i am confused weather to stick with these spark plugs or change them to BR9 and 10 or go for BR9ET whor all spak plugs.

Advise please what can be difference in plugs and if this can be cause of heavy backfire and higher fuel consumption of car. Also spark plugs are geting burned in 1000km is this caused by wrong spark plugs or is this bad ignition coils.

THX

 

Think you mean the NGK brand BUR7EQ and BUR9EQ instead of the BRU7EQ and BRU9EQ.

The BR9ET, BR10ET are an older design found on earlier model rotary engines (uses 3 ground electrodes instead of 4). They actually came stock on the 86 models here in the states, but were replaced with the updated 4 electrode BUR7EQ and BUR9EQ whenever you visited the dealer for the first time for service and on all 87+ models came stock with.

You would probably be better off using the BUR7EQ and the BUR9EQ or the Denso W27EBR and W31EBR. The other plugs available are the NGK BUR7EQP and BUR9EQP.