Boost Problems at high Psi - Spark Plugs???

**LinerR33** · 10-18-2011, 05:33 PM

So my RB25DET is running a Fuzzy Boost Controller and Apexi SAFC, and all last year and up until recently i was running about 0.8 bar fine all the time. I had a tune-up done and had some spark plugs replaced from the copper to some high performance ones (cant remember if theyre iridium or not...)

Shortly after this anything above 0.6 bar causes severe jerking/flat spots/backfires at high revs, and the higher the boost the lower revs it happens at. Yet if the FBC is off there is no issue.

The only thing changed was the spark plugs, i didnt mess with the ECU or SAFC, yet its fine without the boost turned on!?!?

Ive looked around and seen it might be coil packs or gapping the spark plugs smaller. Or i was thinking changing the spark plugs back to copper ones might fix it??

Any insight is greatly appreciated

**DarkCaporaL** · 10-19-2011, 08:43 AM

Start by pulling your plugs and making sure they are gapped at 0.8mm.

For future reference you can stick to copper, it's cheaper and it does the job.

**Supraclean** · 10-19-2011, 10:52 AM

Originally Posted by DarkCaporaL

Start by pulling your plugs and making sure they are gapped at 0.8mm.

For future reference you can stick to copper, it's cheaper and it does the job.

What Dark said. I run my car hard at 13.5 psi all day long on coppers. Work great have spares or spares for the price of Iriduims

**frankiman** · 10-19-2011, 12:00 PM

try reducing the spark plug gap

**MKIV** · 10-19-2011, 06:53 PM

While this topic is open, are spark plug upgrades needed based on boost or hp?

When do RB25 usually need better sp's? Thanks

**TyrelLee** · 10-19-2011, 09:06 PM

I had the same issue with my rb20 and it ended up being a vac leak. See if you forgot to hook up a line and/or if one blew up.

**ChezoGTR** · 10-19-2011, 11:48 PM

had the exact came issue. pulled the so called high performance iridium plug tossed em, put copper plug gapped to 0.8mm and she runs like a magical unicorn now

**trickey1991** · 10-20-2011, 12:35 AM

the guy that tunes my car told me its always good to run better then needed spark plugs, I run NGK BKR7E plugs in my 20, gapped to .8 i believe and it made a HUGE difference when i got the car tuned It was breaking up because of the spark plugs not being gapped so almasi told me to gap them and run just like 9lbs until i did gap them, well i forgot and cranked it to 12lbs and it backfired and broke up so bad. Gapped them the next day and it runs like a dream

lol

Originally Posted by MKIV

While this topic is open, are spark plug upgrades needed based on boost or hp?

When do RB25 usually need better sp's? Thanks

**Skym** · 10-20-2011, 07:18 AM

MKIV, roughly every 75-100hp go one heat range colder. Or change heat range when engine is too rich (hot) or too lean (cold).

Read FAQ section of NGK website -

http://www.ngksparkplugs.com/tech_su...x.asp?mode=nml

**MKIV** · 10-20-2011, 05:34 PM

Originally Posted by Skym

MKIV, roughly every 75-100hp go one heat range colder. Or change heat range when engine is too rich (hot) or too lean (cold).

Read FAQ section of NGK website -

http://www.ngksparkplugs.com/tech_su...x.asp?mode=nml

Thanks good info!

Are RB20 & RB25 interchangable?