Technical > Automotive > [Help] New Spark Plugs = Worse mileage

[Help] New Spark Plugs = Worse mileage

What spark plug does the vehicle manufacturer specify for that vehicle? I have run into many situations where Platinum plugs were installed when not indicated and resulted in reduced performance. If it is the correct application, then I would confirm that they have been properly gapped per specs.

I concur, I had a 95 Civic that spec NGK and I stuck in some Bosch Platinum and my MPG dropped like a rock. Went back to the manual and got the specified ones and it went up and slightly above previous MPG.

reply to simiglen
Do you have a 4 cyl or V6? Ex or Lx on the trim level? Also do you know if you have a 48 state emissions or California emissions? makes a difference on the plug needed.
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reply to simiglen
1mpg is very small difference especially at only 5k sample. So many different things that could be factor.
Heavier foot.
Different gas.
Weather.

Myself I wouldn't worry about it.
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In need of a Vegas vacation.

reply to santy
I have the EX v6. I have the California Emissions

As for other questions this was the plug specified.

reply to simiglen
Obvious question: did you gap the new plugs as per factory spec before you installed them?

reply to simiglen
Are you sure that is the plug specified in the owners manual?

Hondas catalog shows only one plug for a EX V6 Cali emissions vehicle and that is SKJ20DR-M11 (DENSO) HONDA NUMBER IS: 9807B-5615W

you can go here www.bkhondaparts.com and see for yourself.. you can put in the vin number also if you want... Cali emissions is defined as KL in the transmission selection. KL5AT for the auto and KL6MT for the manual.

and yes I work at that dealership.
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You don't quit playing 'cause you're OLD. You're old BECAUSE you quit playing!!

reply to simiglen
Seriously? 1 MPG? or slightly less than 1 MPG? OK...

I would not have used other than the Honda OE plug or the direct replacement equivalent, In many cases, a plug "upgrade" isn't.
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"from a broken heart to a hole in the sky"

He thought he got the super-duper performance/ economy plugs.

quote:

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The gap adjustment can be crucial to proper engine operation. A narrow gap may give too small and weak a spark to effectively ignite the fuel-air mixture, while a gap that is too wide might prevent a spark from firing at all. Either way, a spark which only intermittently fails to ignite the fuel-air mixture may not be noticeable directly, but will show up as a reduction in the engine's power and fuel efficiency.

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The -11 in that spark plug number means 1.1mm gap ...PRESET, exactly perfectly, and it is boxed with a very durable sleeve over the business end.
I have never seen one fubar, not once.
I've probably handled 10,000 of them, honestly. Perhaps not that exact part number, but close enough.

I'll lay it out like it was spelled out to me by a guy with the name of Drake (yea, Drake from Offenhauser...that Drake).

"If there is enough spark to light the fire (no misfires) there is enough spark, more will not light the fire better, it is just wasted energy (drag from the alternator and lesser power to other devices)."

1 mpg is really impossible to gauge, too many variables.
Like say a different batch of fuel at the local pump ????

reply to simiglen

Doc, as always, you're the man!

reply to simiglen
Sometimes it's wise to pull a plug first and check the part number BEFORE you shop. My first new car was a 1986 Plymouth Colt GTS Turbo that had ND plugs with a number slightly different from the under hood label; I ALWAYS replace what I pull with an exact match and have never gone wrong with this.
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