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My Engine Does Not Like Colder Plugs

limpus

By limpus,
in Engines & Forced Induction

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limpus Mentor

limpus

Posted
Posted

Hi guys, I was wondering if you had any input on this problem i am facing at the moment.

I just got a hks 2535 onto my rb20 and got a dyno tune...during which we found the current plugs were too hot and so we whacked some heat range 7 plugs on which were gapped at 0.8mm...when that was done the tune was all good but i have found that the car now idles terribly now...it constantly hunts between 700-1000rpm and misses occasionally...the car however idles fine with heat range 6 plugs...does anyone have any suggestions? what can i do to improve idle quality?

Russco Proficient

Russco

Posted
Posted
Anyone? I was thinking of splurging on some SPITFIRES but i'm not keen to do so if the coilpacks aren't the problem...

Splitfires won't help if it's fouling all 6 plugs. I;'d check your AFR at idle/light throttle to see if it's running rich - this will foul plugs quickly. 7's s/be ok on the street if you give it some full throttle a couple of times per week to clean off the plugs. I found copper 7's gave me a lumpy idle/slight fouling wheras platinum 7's ran smoother & didn't foul as much (but blew out under high psi unlike the coppers).

Risking Grand Master

Risking

Posted
Posted

How did you come to the conclusion the plugs were to hot??

I have used 6's in 350-400Kw engines and never ran into problems. All said engines run 7's when they are on the track but for most use they are happy with 6's

However id be looking at the AFR at idle and going from there. Its goingto be tunning issue if you really do need to run 7's

limpus Mentor

limpus

Posted
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Posted

It was to reduce detonation...we were getting decent results at 14psi with 6s but then when i wound in 18psi and after several power runs detonation got pretty bad...so you say that you have run high powered engines on 6s with no issues? if so then i might have to look deeper into this matter...i kinda figured that the coils were fine as the engine idled flawlessly with 6s...

Cubes Grand Master

Cubes

Posted
Posted

What were the water temps like?

Possibly that was partially the cause of det.

6's are fine as said for 300rwkw, I've seen one push close to 400rwkw on 6's without problems.

When I ran 7's I had to put a bit of work in to the temp correct table as the defaults were simply too rich and would foul the plugs.

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