taylorgang

iTrader: (5)

I've been getting my car tuned and I noticed a kind of popping sound around 3500 rpm... then noticed under boost at higher rpms the car would backfire a lot. I was told the popping sound was spark blowout.

In my mind it would make sense if the spark plug has blown out then there's a lot of unburned fuel being sent through the exhaust which is resulting in the backfire. Does that sound right?

Also... after reading tons of threads I know there's a lot of mixed opinions on this... what spark plugs are best for an evo 8 around 400whp?

I got a set of NGK BPR8ES from autozone and will be gapping them to .022


I just want some peace of mind and want to be sure I'm not damaging the turbo/engine. If someone cares to explain the details of a spark plug blowing out that'd be great too (obviously it's bad to drive with a blown spark plug but what exactly happens?)

awdordie

iTrader: (1)

Doubt it can be "bad" you just aren't making the power you would be. Your explanation of the problem sounds about right. When I had this problem I also noticed a huge cloud of black smoke like a diesel. I think it can also raise egts if im not mistaken.

BoosTyEVO

I make 381 whp 386 wheel tq and I use the bpr7es gap to 20 thousands I realise i will have to change them probly every other or every couple oil changes as they really do fowl somewhat quickly but havent had the spark blow out issue

taylorgang

iTrader: (5)

Thanks for the replies guys I think I'm gonna try these bpr8es gapped at .022 and see how it is

Jwhalen07

iTrader: (6)

I think the 8s are too cold. I would spend the 10 bucks and buy the 7s. Try .22 but don't be afraid to go into the .18-.20 range. You might notice a miss at idle but the WOT miss should disappear.

1UpMoto

iTrader: (14)

try the Br8es instead of the Bpr8es. Some people seem to have better luck with them than the bpr8es.

D-VO

iTrader: (1)

+1^^

I'm using the BR8eix in mine and I'm making around the same power.

taylorgang

iTrader: (5)

I just installed bpr8es.

Attached my old plugs in the pics... too rich right?

There was tons of gap too like .030ish


I think I gapped it around .022 - .024 does it need to be loose around the area you want?
Or should it be so tight that it doesn't go past .022 when I want .022?

taylorgang

iTrader: (5)

keep in mind I'm gonna be running e85... not sure if they're supposed to be gapped down more for e85?

novem

iTrader: (2)

They look rich for sure! Spark blow out is a combination of high boost and, or plug gap, type.

N

kanyonkid

iTrader: (33)

ur right on the money for BPR8ES at .022.... put em in and listen to her purr

Hardware

iTrader: (17)

You should really talk to someone who knows what they are doing. Don't take the blow out lightly. I had a similar scenario in high boost with the exhaust popping and before I figured it out it threw a rod. My problem could have been totally different, but I'd still be very careful.

The way I understand it is that if you have a cylinder running without spark the internal parts (rod for sure) take additional stress and break. Hope you get it sorted out.

ProPilot04

iTrader: (11)

Spark blowout is definitely bad.

To be more specific, anything happening aside from the normal suck squish bang blow is bad.

If your spark is getting blown out, it is typically caused by high boost applications and a plug that is not properly gapped. There is no situation where "some" spark blowout is acceptable.

What is ultimately happening is that there is an injected fuel charge that is not being burned in one cylinder. This means that for that stroke, there is no combustion in that cylinder. With no combustion, the cylinder is not being forced down. That means that for that particular revolution, the motor is basically only moving due to momentum. This is bad for a myriad of reasons. There will also be that unburnt fuel going into your exhaust system which is also bad as it can create detonation in the exhaust (this is different from detonation within the motor) often referred to as afterburn.

So then... a couple of things.

1. You said you were getting tuned. If your tuner let your vehicle leave with this condition, I would probably find another tuner. Does spark blowout happen? Yes. But any reputable tuner should be able to quell this problem before leaving it with their stamp of approval. Of course... bear in mind, we're only hearing your side of the story here.

2. Check to make sure your plugs are gapped appropriately.

3. I would either not drive your car until you can fix this problem, or keep it as out of boost as possible until its fixed.

4. The FIRST thing I would do, is a boost leak test (properly). Then I'd pull the plugs to examine them and see what they're gapped at. If the car passed the boost leak test, (so you can rule out the a boost leak was what caused this) I'd be very critical of the plugs and talk with the tuner immediately. If the plugs look fine, and the boost leak test was ok... seek professional diagnosis.

taylorgang

iTrader: (5)

I got new plugs

And the car is being tuned by a very reputable tuner. He was the one that discovered the problem, so if it wasn't for him I'd still be driving around with blown plugs

Thanks for all the replies though hopefully this thread can help out people who encounter the same problems that I did.

taylorgang

iTrader: (5)

And can anyone tell me how to properly gap using the coin gapper? Does the middle of the tip need to line up with the gap number you want?