4AGZE Spark Plug Gap

Alex170984
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4AGZE Spark Plug Gap

Postby Alex170984 » Mon Oct 01, 2018 6:57 am

Hi,

What is the preferred gap for spark plugs on the 4AGZE?

Also, does anyone have a part number for plugs required when running the big pulley and ABV mod?

Cheers

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jondee86
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Location: Wellington, New Zealand

Re: 4AGZE Spark Plug Gap

Postby jondee86 » Mon Oct 01, 2018 2:21 pm

I'm using these...
NGK BKR7E Standard V-Groove plug, gap 0.80mm (one heat range cooler than stock).

I'm also using the OEM GZE wasted spark coils and found that I was getting some
misfiring at WOT/high rpm (12-14psi). Gapped the plugs down to 0.60mm first and
that helped, but I had to gap them down to 0.50mm to eliminate the misfiring. Don't
know if the coils are weak or if I have a bit of voltage drop in the coil power supply.
Spraying water/meth when boosting probably doesn't help either.

In any event I am going to run a new power supply from the battery, change to coil
on plug and fire them sequentially to make sure I get plenty of spark :)

Cheers... jondee86
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Alex170984
Club4AG Expert
Posts: 282
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Re: 4AGZE Spark Plug Gap

Postby Alex170984 » Tue Oct 02, 2018 5:26 am

So the mr2 manual saying 1.1mm is incorrect? The gap would also make sense as i was suffering from a mysterious misfire before i took my engine apart for rebuild.

Thanks Jondee

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jondee86
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Re: 4AGZE Spark Plug Gap

Postby jondee86 » Tue Oct 02, 2018 2:26 pm

The AW11 manual says BCPR6EP11 for the bigport distributor GZE, but the JDM
smallport DLI GZE calls for BCPR6EPN8. As I am using the equivalent of the JDM GZE
with coilpacks I started with 0.80mm gap plugs. My s/c is permanently ON (no clutch)
so heat range 6 was too hot, and I moved to heat range 7; even ran 8's for a while.

Generally speaking, if you are over-boosting a stock bigport GZE you would be
advised to run 0.80mm gap and heat range 7.. The cheaper standard NGK plugs
work fine. Higher boost levels put more load on the ignition, and as I have found,
you can get misfiring (AKA spark blowout) at WOT and high rpm. Short term fix
is gapping down but long term fix is a stronger ignition system.

Cheers... jondee86
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Alex170984
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Posts: 282
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Re: 4AGZE Spark Plug Gap

Postby Alex170984 » Wed Oct 03, 2018 6:10 am

I found two broken spark plugs pre rebuild as I bought the grade 6 plugs by accident.

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jondee86
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Re: 4AGZE Spark Plug Gap

Postby jondee86 » Wed Oct 03, 2018 2:19 pm

The not good, the bad and the ugly...

Image

Broken plugs are caused either by pre-ignition or detonation. Sometimes the
ground strap gets blown away, sometimes the insulator has pieces missing, and
sometimes the electrode is burned up. Apart from destroying plugs either of these
conditions will damage other engine components if it becomes severe.

You need to watch your AFR's (wideband), intake air temperature and listen for any
knock (pinking) under load. When you start boosting on your new engine work up
to WOT gradually and observe the plugs for any signs of overheating or "speckles"
on the insulator. Do not let the engine run too lean and investigate right away any
time you feel misfiring.

Cheers... jondee86
Give a person a fish, they eat for a day. Suggest they search before posting, and they learn a skill for a lifetime.

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oldeskewltoy
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Re: 4AGZE Spark Plug Gap

Postby oldeskewltoy » Thu Oct 04, 2018 10:23 am

and sometimes the broken electrode beats up the chamber before embedding itself in the head... :cry:


Image
OST Cyl head porting, - viewtopic.php?f=22&t=300

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