less engine braking with iridium plug

[Stig / Major Tom]

Hello, OK, don't know if I'm going to stay with this new NGK iridium spark plug. There is a marked loss of the engine braking that I've been accustomed to .

Has anyone else experienced this with iridium plugs?

 Whatever I might be gaining in MPG's, MPH , etc. will be lost in the price of replacing brake shoes! Plus I must learn to ride differently now.

Not sure at all that it idles faster - just that the fuel injection is dealing differently with my rolled off throttle.
Without a tach I'm just guessing by the sound that my scoot is idling quicker maybe not,  or is it just smoother with the iridium plug?
The rear wheel does not turn at idle - but the delay in slowing when I roll completely off the throttle while riding at speed is quite noticeable with this  iridium plug. It does come back down to idle ---- but with a noticeable delay. Less 'engine braking'.

The scoot runs fine otherwise.......

Your thoughts......

[tclhb]

Engine braking is important to me. When there's light traffic I get my kicks by seeing how many miles I can travel with out touching my brakes. Both by timing the lights and engine braking.

[TroutBum]

Doing a search I found nothing that would change your engine braking characteristic when using different types of spark plugs. Could it be that when you adjusted the valve gap that the braking compression you once had is now lost do to the adjustment that you made?

[Vivo]

Stig, spark plugs just spark... it's a split second job...and Iridium just does it efficiently... meaning, no misfires... nothing to do with other things...   

[Stig / Major Tom]

Doing a search I found nothing that would change your engine braking characteristic when using different types of spark plugs. Could it be that when you adjusted the valve gap that the braking compression you once had is now lost do to the adjustment that you made?

No, the valves were done awhile ago....no change - just a nice Singer Sewing Machine noise down there.
Days later I put in the iridium plug, and the idle has increased....which is quite noticeable when you roll off the throttle with increased idle...you simply do not slow down as quickly with an even slightly increased idle speed.
Modernbuddy folks suggested trying to re-set the ecu to 'learn' this new & different spark plug (because it is a different electrical piece in the system). They suggested disconnecting the battery; and switching on and off w/out starting 3 times at 3 second intervals. These had no effect.

[MaryK]

Did you try putting the old plug back in ?

Or a new std.plug ?

[Stig / Major Tom]

Stig, spark plugs just spark... it's a split second job...and Iridium just does it efficiently... meaning, no misfires... nothing to do with other things...   

My two centimes :  I have read reports from various scooter owners that installing an iridium plug has raised their idle speed (around 300rpm)
That is nice---- a cleaner little ball of super-spark "making nice" with the fuel and the compression and electricity, etc., etc. to the extent that the idle increases a bit. Same draw is going to the plug, which needs less = idle up.
However, turn the idle up on any vehicle and you will notice a different response when you take your foot off the gas pedal! Engine braking will be different.
Modern fuel injected engines generally have much less engine braking than non injected engines (lots of polluting going on during engine braking) Less engine braking, less pollution from the engine. There is always a delay when you roll off the throttle on modern engines ( big difference between my 25 yr old VW Jetta and a new Toyota. Need lots more brakes on the new Toyota due to loss of engine braking.

OK, so this new plug ( and all 3 service people I've talked with say that if you stay with the same heat range number from the manufacturer - stock plug vs iridium plug - operating temps are a non--issue. "Manufacturers list plugs in the proper heat ranges. If an iridium plug operates hotter than a copper plug - this is not news to the company - they build/sell the iridium plug to match the correct (read "SAME") heat range for the engine."

i.e. : "....a 7 is a 7 , an 8 is an 8."  Same brand plug = different type construction, a 7 is a 7, and 8 is an 8. They are constructed this way.

Failing a simple method to re-set to the fuel injection/ ecu - I'm likely going to pull out the  iridium plug for the stock plug. Changing heat ranges is not the issue, engine speed is.







 

[Stig / Major Tom]

Did you try putting the old plug back in ?

Or a new std.plug ?

That's next, if I don't find a simple solution to lowering the idle speed.