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Misfire under boost - Updated w/ ugly plug pic and new problems

EfiniX

Well-known member
Joined
Oct 18, 2012
Messages
647
Location
portland, or
The last time this happened, it was on a dyno and English Racing re-gapped the plugs. All was well after that. Now it's started to misfire again about a 4 months later. I'm not sure how old the plugs are, but I've got 4 new BPR7ES plugs sitting on my kitchen table. I'm running 20PSI right now on 92 with cams and an intercooler, 950cc injectors, and other assorted bits. I swear ER said they gapped to .021, but that sounds VERY small to me.

What's the consensus here? Gap for BPR7ES=...

My guess is 0.028
 
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EfiniX

Well-known member
Joined
Oct 18, 2012
Messages
647
Location
portland, or
Well this is interesting. Cly #3. Looks like detonation to me (the electrodes are actually pitted a bit). The plugs were old, so I'm wondering if this one fouled, then misfired and detonated itself to death today. New plugs gapped to .028 installed and the car seems happy again.

So, thoughts on what could cause this ickiness.? I verified I don't have coolant in my oil, and my A/F (Innovate WB) looks fine and has been fine since the last tune under all loads.


 
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slugsgomoo

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Joined
Oct 16, 2003
Messages
3,776
Location
Tacoma, WA
go to the non projected tip plug. BR7ES > BPR7ES.

without seeing a log I couldn't say but that plug looks like it's been lean to me.
 

turbowop

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Joined
Apr 29, 2001
Messages
11,971
Location
Yakima, WA
I use non-projected 7's in my car @ .020 with methanol injection. Before methanol injection, I just ran normal projected plugs at around .022 or so.
 

EfiniX

Well-known member
Joined
Oct 18, 2012
Messages
647
Location
portland, or
Quoting slugsgomoo:
go to the non projected tip plug. BR7ES > BPR7ES.

without seeing a log I couldn't say but that plug looks like it's been lean to me.



I should point out that the other plugs came out looking fine.
 

EfiniX

Well-known member
Joined
Oct 18, 2012
Messages
647
Location
portland, or
So it gets better...

I drove around for about 2 hours today before noticing the same issue I had yesterday. First, the car isn't running as well as it did a few days ago. Just not pulling the same and it sounds a little funny. A/F looks good and I'm not seeing knock, but it just doesn't have the same get up and go. Well I was driving up a hill and went to pass a Camry. Hit the gas in 4th and as I hit 10psi, the car started to stumble again. i backed off and headed right on home. The car holds idle just fine, and when it's running, it seems to be running agreeably. Still, a little sluggish all-around, and acting like a punk when I put load on it.

One other thing happened of note... For the first time since I got a new dipstick about 6 months ago, the stick blew out and sprayed oil under my hood. Now I didn't come close to the 20PSI I was running just a few days ago fine before this problem cropped up. So now I'm wondering if I've lost compression in cyl. #3 (where the ugly plug came from) and now I'm getting blow-by and consequently, more pressure in the sump. I'm no expert in these things, so I don't know if blow-by could have also hosed the plug, but it seems possible.

Or maybe I have a bad injector and this one cylinder is running lean?

At this point I think I'm going to have the head pulled, check the pistons and sleeves, check the head gasket, and have the #3 plug threads repaired as they were pretty munched up by the last owner.

Oh, and once last observation. My walbro 255 was noisy as hell while idling in my driveway when I got home. I don't know if it's normally that noisy, or if I'm just hyper-sensitive to this stuff right now, but it seemed loud.





 
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