Misfire in #2 after boosting
Thread Starter
Joined: Sep 2004
Posts: 2,552
Likes: 12
From: Visalia, California
Misfire in #2 after boosting Well, could be the end of my ls1, not sure yet, it still runs but dead in #2 hole. It backfires, but not every time, not sure if that's normal. I was able to limp it home, didn't hear any knocking or rattling, but could feel that i was down at least one cylinder. I turned the boost down to 5# yesterday for safety's sake until the new motor is built and guess it gave out. I figured #7 or 8 would be first to go... Wonder if I perhaps have a broken valve spring or burnt valve, kinda strange. What do you all think?
Launching!
Joined: Oct 2002
Posts: 256
Likes: 0
From: Tulsa, OK/Gainesville, Fl
If its just a misfire it could be as simple as a burnt plug wire. Thats what happened to me when i first added the turbo. The inside of the plug wires got melted and no one even noticed until one broke open 
Thread Starter
Joined: Sep 2004
Posts: 2,552
Likes: 12
From: Visalia, California
So weird how it came out of nowhere... I'm gonna take the plug out tonight, and get the compression tester from the old man's house and check it out. The plug wires are MSD's, and relatively new. I know exactly what you mean by the broken/burnt plug wire, it'll break up like hell, same with cracked porcelain on the plug. I hope it doesn't turn out to be something ish-y. My block, and crank should be here this week... Already have the heads torn down and being machined. EESH... this sucks...
Thread Starter
Joined: Sep 2004
Posts: 2,552
Likes: 12
From: Visalia, California
Here's what I found when I pulled the plug on #2... A wet silver fine metallic substance like lapping compound almost on the threads and the spark plug tip was mashed together and had a couple dings like it was smacked around. I'll do a compression test tomorrow, see if the block is toast in that cylinder.
Thread Starter
Joined: Sep 2004
Posts: 2,552
Likes: 12
From: Visalia, California
Well, got the passenger side head off tonight, bad news... piston broke above the ring land. Couldn't find the chunk but I think it was nuclear meltdown... even worse, the block is cracked... Check out the pictures... 
Directory for low and high resolution pictures of the damage...
Directory for low and high resolution pictures of the damage...
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Verdad Gallardo Thread Starter
Joined: Sep 2004
Posts: 2,552
Likes: 12
From: Visalia, California
I have to pull the turbo off... It could be anywhere in the exhaust going to to it... although driving it with 1 hole down, the turbo would spool up some, and sounded fine. I'll have to check and see, that'll ruin my day if it jacked the turbine. Fortunately I already bought a new block, crank, heads, valve springs and timing set... Good portion of a new longblock I guess =\. Just wish it wouldnt've gone like this...
TECH Resident
Joined: Jan 2002
Posts: 956
Likes: 0
From: Phoenix, AZ
That sucks man!! That picture looks EXACTLY like mine when it blew . . . never found any pieces, but there was material on the drain plug. My block also got cracked. That being said, since I've had the new motor in the car, the passenger side turbo has been leaking/smoking oil . . . I wonder if my turbo was damaged in any way. Odd thing is it was #1 piston, yet passenger side turbo is the one with the problem . . .
Thread Starter
Joined: Sep 2004
Posts: 2,552
Likes: 12
From: Visalia, California
I was only running 5#, had it turned down, must've had a bad feeling, was just telling the mrs. that morning that I hate having an engine I have to worry about... So... as a safety precaution, I turned it down... and there it is, blew it to pieces anyway. It was probably from the oil in the top end and more boost, detonation city.
ok i was just talking with my friend about our motors before we go boost like you did-67FIREBIRD....um yea so what we were discussing is before we even turbo it or do heads/cam/manifold swap, we should invest in some nice forged pistons w/ upgraded piston rings to prevent THAT from happening ....and also put in some ARP rod bolts/studs but leave the stock rods....u think that sound like a good idea -forged pistons with stock rods should def. hold right??? 
just wanted to ask especially now that i see what happened to ur piston, sorry to hear it anyways man hope ur turbo's OK, take it easy and hope ur next motor kicks *** 
....and also put in some ARP rod bolts/studs but leave the stock rods....u think that sound like a good idea -forged pistons with stock rods should def. hold right??? just wanted to ask especially now that i see what happened to ur piston, sorry to hear it anyways man hope ur turbo's OK, take it easy and hope ur next motor kicks *** Thread Starter
Joined: Sep 2004
Posts: 2,552
Likes: 12
From: Visalia, California
You can get away with boosting a "stock" motor if #1 the tune is right... #2 You don't have dumped in the top end that would cause detonation. Mine grenaded due to that...
Sorry about your motor. Man your pistons look clean for 97K. I just did a head swap on my motor with about 39K and they looked like this. The motor was pulled out of a 98 vett with 36K. I put about 1K on it running pig rich and 2K on it running tuned. Why are my pistons so black? How can I get rid of all that carbon?
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