Julien Scherer

My car started recently to puff a lot of oil (like 1L/100km) and the car was misfiring big time with huge clouds of oil (like gray/blue) so I did a compression test and checked my sparkplugs at the same time to see if there was oil in the cylinders. 1 and 3 were ok but 2 and 4 had a lot of oil on it. Compression test read 120-80-120-70 which is really bad. My question is could it be the pistons rings that are leaking or more like the valves seals?

63 Nova SS

iTrader: (3)

I highly doubt it's the valve seals. You probably have worn out rings or have issues with the ring lands. Either way those numbers don't look good, even on the higher cylinders. You should see 150-160 provided you aren't at high altitude.

ECaulk

iTrader: (6)

Get a leak down tester and take the valve cover off and see where the pressure is going on cylinders 2 and 4. That will tell you quickly if the valve seals are leaking or if the issue is in the rotating assembly. How many miles are on your SS?

Julien Scherer

The car has 83 xxx miles but it was running on a Trifecta tune for "I don't know how long" for stock map sensor before BUT with a 2.5 bar lsj map sensor on the intake manifold and a 3 bar on the cold side with a **** ton of misfires when I bought it. The engine didn't have it easy on that for sure. The last owner was a complete moron who didn't know how to tune his car properly. I changed everything to 3 bar map sensor and I got rid of trifecta for an hptuner tune but was always having misfires during nls. I changed the spark plugs and coil packs for stock ones. The car started puffing oil after a nls 2-3 a couple months later (this weekend) and it was really bad..

keiserX13

iTrader: (3)

if it misfired during NLS why did you keep doing them?

Slowbalt2000

iTrader: (1)

Julien Scherer

It was misfiring only during a 3-4 nls, 2-3 I didn't have a single misfire

Julien Scherer

I will need a complete rebuid for sure, but I just want to know what can cause the low compression in cylinders and oil in cylinder 2-4

ECaulk

iTrader: (6)

See above.


But honestly fucked ringlands, fucked headgasket, valve guides may allow oil. But either way that motor is either being replaced or rebuild in which case you should start buying parts needed to at least tear it down. (head bolts, head gasket, would recommend a full timing kit since you'll need to re-time it anyways)

umrdyldo

iTrader: (1)

If he ran the Trifecta tune for long enough, I'm guessing the ringlands were on the way out when you bought it. It's known for being too rich and killing rings.

Easiest path from here is to just buy an LDK or similar from ZZP and move on. A rebuild is just as much work or more and not guaranteed to be perfect.

I'd do a tear down to see exactly what failed or if it is in fact the rings. Could be valve seats from oil coking on the valves, could be a ton of things really. PCV system is probably screwed.

I still can't believe someone ran it with different map sensors. Does that even work? I have never heard of someone doing that.

Julien Scherer

Above 5500rpm on each gear the car misfired with no possibilities of power at all, like if i was in neutral with the foot on the floor but with misfire noises lol

jdbaugh1

iTrader: (1)

What exactly does the excess fuel do to the rings or ringlands? Does it make them wear prematurely or what?

umrdyldo

iTrader: (1)

I was always under the impression that it washed the cylinder walls and reduced the oil lubrication which increases wear.

Julien Scherer

Trifecta also does a **** ton of knock retard

ECaulk

iTrader: (6)

That's the issue, and increased soot with the direct injection

jdbaugh1

iTrader: (1)

Makes sense. I'm on Trifecta tune but I think mine is more dialed than the old standard tune. Steven has told me that most tunes were usually 3 to 5 revisions and case closed. For this time on my car we had probably near 30-40 revisions. My AFR is around 11.8-12 at WOT. Running 22 degrees ignition timing. I don't even have my knock sensor plugged in because it pulls all the timing all the time because my ECU detection method is way overly sensitive. My knock sensor is my ears and my IAT2 sensor is standalone. Idle is a little funky at times but damn it seems to run good when I'm on the throttle. It's not ideal but I haven't bitten the bullet to go standalone ECU yet.

Julien Scherer

What is better between rebuilding my actual engine or buying a used one with low mileage? If we don't talk about the budget range obviously. I found a LHU engine with 3000 km on it for 1725$ CAD near me, maybe I will swap it in my car but rebuilding my LNF will cost me 1500$ CAD (I have a friend working at GM)

Henry3959

Nothing another rebuild won't fix
Some enjoy rebuilding rather than properly tuning.

jdbaugh1

iTrader: (1)

Lol I know you're poking that at me but doing a couple pulls while running rich isn't what he was talking about. I was running 10.5 for a couple pulls I did while street tuning, which is completely necessary before it can be adjusted leaner. I made that video while data logging. Also it wasn't far away from stock LSJ AFR on stage 2. Surely if running 10.8 was going to ruin your engine in seconds, GM would have set them to run a little leaner.
Reference:



Edit: Sorry to thread jack y'all.

Henry3959

No... but if the shoe fits