06 LS2 - Random misfire and metal in engine

4963 Views 61 Replies 13 Participants Last post by BRZN, 15 d ago

SkiPopeye36

Discussion Starter · 5 mo ago

4

Long story short, it looks like a 14k mile LS2 in a friends GTO (Dave “BRZN”) is beginning to consume itself.

We’ve been chasing an intermittent random misfire for years. All the typical electrical items were checked (plugs, wires, coils) to no avail. Swapped on some new Kooks headers last month as well as some new plugs. Winter hit here and didn’t get a chance to take it out for a drive and do some data logging to see if somehow the headers and new plugs miraculously fixed the issue.

Last week Dave decided to do an oil change as it’s been awhile since he last did one (roughly 1k miles and a couple of years as it’s a summer garage queen). Found some crap on the magnetic drain plug and thought he’d open up the oil filter.

I can’t upload the video, but attached is a still picture of the video. There’s a lot of glitter in there. Took the valve covers off and saw what you see circled on the passenger-side. These are SLP 1.85 rockers if that makes any difference.

We’re already prepared to pull the engine in the spring, but anyone want to guess what’s going on? This is a bolt-on LS2 with the stock cam and heads, so nothing more than the aforementioned rockers and headers on the car.

Rockers deteriorating? Lifter failure resulting in taking out a cam lobe? Bearing failure?

We did a compression check last weekend and all cylinders were down 5-10lbs from when we last checked the compression in 2016. Began a leak down test before I had to leave and those results all seemed around the same as previous and within the normal range, so we don’t believe it’s a dead cylinder somewhere.

Planning to pull the rockers next to see if one of those SLP rockers is destroying itself.

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Nothubertjfarnsworth

· #41 · 4 mo ago

Mr. Black said:
You messing with me?

It's simple math.

no. he's not changing his lift that much. he's at like .571" valve lift or so with the 1.85 rockers. the rocker tip is in the exact same spot as a stock rocker. it's the same tip weight and overall weight as a stock rocker. it's still the stock cam. his springs are basically just a slight upgrade to handle the increased lift.

so, i dunno, educate me on what you're talking about?

Mr. Black

· #42 · 4 mo ago

Leverage is leverage. Anytime you increase leverage there is a load change on the pivot.

Nothubertjfarnsworth

· #43 · 4 mo ago

Mr. Black said:
Leverage is leverage. Anytime you increase leverage there is a load change on the pivot.

so get a better trunnion setup. these types of trunnions self destruct on stock rockers, too.

Nothubertjfarnsworth

· #44 · 4 mo ago

you don't think guys running 400+ lb springs with aggressive ramp rates put much more than the stock load on the trunnion?

Mr. Black

· #45 · 4 mo ago

Nothubertjfarnsworth said:
so get a better trunnion setup. these types of trunnions self destruct on stock rockers, too.

one out of every 1 million?

Mr. Black

· #46 · 4 mo ago

Nothubertjfarnsworth said:
you don't think guys running 400+ lb springs with aggressive ramp rates put much more than the stock load on the trunnion?

I'd be running aftermarket big boy shaft rockers at that point but that's just me.

Reactions: 1

Nothubertjfarnsworth

· #47 · 4 mo ago

Mr. Black said:
one out of every 1 million?

nope. this failure is common with the comp style trunnion setups, which is basically what SLP used.

Reactions: 1

Nothubertjfarnsworth

· #48 · 4 mo ago

Mr. Black said:
I'd be running aftermarket big boy shaft rockers at that point but that's just me.

lots of folks do fine with this sort of stuff, again, it's pretty common. stock rockers have proven themselves. some of the aftermarket trunnion setups, have not.

Mr. Black

· #49 · 4 mo ago

Nothubertjfarnsworth said:
nope. this failure is common with the comp style trunnion setups, which is basically what SLP used.

I was thinking stock not the comp crap.

Reactions: 1

Nothubertjfarnsworth

· #50 · 4 mo ago

Mr. Black said:
I was thinking stock not the comp crap.

well call up SLP and complain they didn't use stock trunnions.

it's not the ratio causing his issue.

Mr. Black

· #51 · 4 mo ago

No not my beef lol.

Reactions: 1

Nothubertjfarnsworth

· #52 · 4 mo ago

TBH, though, i don't think SLP could have if they had wanted too.

everyone believed that the style of trunnion shaft and enclosed needle bearings that comp (and all the copycats) used was superior. i think it was the only thing available back then, anyway...

Mr. Black

· #53 · 4 mo ago

The reality of my comment or thoughts is I just want to make this car go and see if it's fixed. This essentially a stock engine. Don't over complicate things and keep it simple. KISS

Nothubertjfarnsworth

· #54 · 4 mo ago

Mr. Black said:
The reality of my comment or thoughts is I just want to make this car go and see if it's fixed. This essentially a stock engine. Don't over complicate things and keep it simple. KISS

it's his car. i think all the options have been laid out on the table.

i really don't think there's anything wrong with either putting completely stock rockers in or just putting a different trunnion kit in the SLPs.

BRZN

· #55 · 4 mo ago

4

Believe I found where the metal flakes were coming from:

The needle bearings looked fine, however every trunnion showed evidence of heat stress and each was gouged on the bottom side. I'm still believing oil starvation due to the unnecessary AFM valve opening at WOT dropping the oil pressure when it was needed most.

Picked these up a couple weeks ago and now have them installed in the 1.85 ratio rockers. SkyPopeye's coming over next Saturday and we'll put everything back together and start trying to flush out the engine of any leftover metal flakes.

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Nothubertjfarnsworth

· #56 · 4 mo ago

BRZN said:
I'm still believing oil starvation due to the unnecessary AFM valve opening at WOT dropping the oil pressure when it was needed most.

that's pretty typical wear of that type of trunnion. it just sucks. there's a whole thread about it on ls1tech.

the SLP 1.85:1 rockers i bought on ebay and dissasembled looked very much like that.

Reactions: 1

BRZN

· #57 · 2 mo ago (Edited)

Update
Everything's all back together. A few weeks ago SkiPopeye came over and we ran the car on 5 quarts 0W-16 for one heat cycle, with his HP Tuners hooked up, at idle while still up on the Quick Jack lift. Drained the oil while still warm and found only a tiny bit of metal flakes on the magnetic oil drain plug, the NAPA Gold oil filter looked clear of metal. Refilled the crankcase with 6 quarts 0W-20 and a new NAPA Gold oil filter. SkiPopeye was back over with his HP Tuners last Sunday and we went for a pretty mellow ride, 91 miles monitoring oil pressure, engine temp and misfires. All was good with the exception of a few random misfires shown on the laptop but not felt while driving. Drained the oil while still warm and again found just a wee bit of metal flakes on the magnetic drain plug. The oil filter did have some small specks of metal flakes on it this time. The crankcase is now filled with 6.5 quarts of Mobil 1 5W-30 and has another new NAPA Gold oil filter installed. I've been out on two drives now, one 100 mile, the other 65 miles; no misfires felt, she ran strong. I'll drain this oil and replace the filter after 500 miles.

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Reactions: 4

SkiPopeye36

Discussion Starter · #58 · 2 mo ago

🤞🏽

Reactions: 1

Mr. Black

· #59 · 2 mo ago

That is great news! Now go out and drive the wheels off it!

Reactions: 1

crvtfan

· #60 · 21 d ago

I found my random misfire
, checked only one plug and called them all good. That was a mistake.

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