Iridium Spark Plug

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Feb 21, 2011 | 08:49 AM

#31

atoyot

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Joined: May 2008

Posts: 249

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From: NC

sorry to bring up an old post, but i think i may have put the wrong plugs in.

I am having some tranny shudder and ruff idol after changing out my plugs.

I have a 2000' model and the majority of the spark plug guides show OE gap for this car at .044"? Is that not correct for this model?

Or, is it in fact .8mm (?inches)? I will check my owners manual this evening and see what it says.

Feb 21, 2011 | 10:07 AM

#32

atoyot

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Joined: May 2008

Posts: 249

Likes: 1

From: NC

I just double checked my owner's manual and for my model (2000), it says to use the Denso SK20R11 (.043" gap) plug or the NGK IFR6A11 (.043" gap) plug.

Jan 7, 2017 | 10:58 PM

#33

jakob27990

Driver School Candidate

Joined: Jan 2017

Posts: 29

Likes: 1

From: Ontario

Sorry for bringing up an old post. I just purchased NGK Iridium IX Plugs (.044") for my 96 LS, and looking at the manual it states to use a .043" gap

So are you guys saying I should use a .8mm gap instead of the 1.1 on a 96? I'm confused with the previous posts on this thread.

Also should I decrease the gap down .001 to match the manual specifications if my new plugs are .044? I'm new to working on cars. Thanks!

Last edited by jakob27990; Jan 7, 2017 at 11:01 PM.

Jan 8, 2017 | 12:20 PM

#34

RA40

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From: California

You are fine to leave the manufacturers gap as is. I've not been able to attain .001" precision so I don't try. You'll likely find that attempting to gap them each plug will result in more differences, this is near negligible for the usual commuter.

Jan 9, 2017 | 03:08 PM

#35

YODAONE

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Joined: Nov 2014

Posts: 3,254

Likes: 418

From: CALIFORNIA

Denso spark plug gap chart

Denso is an OEM supplier to Toyota/Lexus
I located this Spark Plug Gap Chart on their website;

www.globaldenso.com/cgi-bin/global/plug/usa/4w/plug.cgi?name=LS400&filename=4w-37.txt&action=search

Earlier in this post it was suggested 1995 and 1996 LS400 require a shorter spark plug gap...
Anyone care to field this one?

Last edited by YODAONE; Jan 9, 2017 at 03:29 PM.

Jan 9, 2017 | 08:47 PM

#36

Yamae

CL Community Team

Joined: Aug 2011

Posts: 4,181

Likes: 1,010

From: Japan

Toyota has changed the design in August 1996 to use spark plugs that have the gap of 1.0-1.1mm (0.0394-0.0433in)
Below is from a JDM manual. It indicates the limit 1.3mm (0.0512in).

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Jan 11, 2017 | 06:32 AM

#37

Oseberg

Rookie

Joined: Jan 2017

Posts: 51

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From: CA

The required gap depends on the compression ratio, air fuel ratio, coil voltage and spark plug temperature. A bigger gap can only make a bigger spark if there is enough voltage to cause a spark under all these conditions, so a bigger gap may create no spark at all under some conditions. But, if the gap is too small, the plug is easier to faul. So, you should follow the instructions and purchase proper temperature spark plugs and properly adjust the gap.