Engine is a built 2.4 stroker with 2,000 miles. Makes 621whp on e85 477whp on 91 octane.

Car blew a turbo water line and I did not catch it and I overheated the engine. I did not pay attention to the water temps. By the time I relised it water temps were at 240. Radiator was full of super thick sludge. I pulled the head and changed the head gasket. I checked the head and block with a straight edge and it looks good.

Now My engine has been having a misfire problem. The compression is 240psi in all 4 cylinders by I also did a leak down test and it shows 30psi leak down in 2 cylinders and the other 2 are about 10%. Is this possible?

Car sounds like a Subaru at low rpm. Sounds like it misfiring. And it breaks up sometimes under boost. Still looses traction in 3rd gear so it's still making big power.

Important note. When I first dynoed this new engine it was having a very similar misfire problem for about 30 mins and all of a sudden. It went away. And it was fine for the 2,000 miles. And now it back after I pulled the head. My tuner things it's a pinch of cut somewhere in the wire harness.

 

For a sleeved forged built motor, 10% leak down is considered good/normal. 30% isn't at all. The next step is to isolate where those cylinders are leaking, wether it be through the crank breather or valves. I suspect if this is related to recent events, it is top end related, through the valves. Its always best to skim the head after blowing a head gasket. It doesn't take much to warp aluminum.

 

motor is running stocked sleeves with the mahle frm pistons and inline pro f24 rods.

i check the head and block with a straight edge per the helms manual and it looked fine. The past few days i have drained the radiator 5 time to try to get most of the sledge out and i think i got most of it out. No more new oil is mixing with the coolent. The car also does not smoke or anything. During the leak down test i saw no bubbles coming out of the radiator.

If you saying the head is not straight shouldent it be leaking out the headgasket? If thats the case shouldent i be seeing bubbles out the radiator when i do a leak down test.

 

You may have a crack in the cylinder head or block. Need to closely inspect the surfaces. I believe there are dyes to test for cracks.
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Ok I fixed it. It turned out to be the pos plug and play clips on the 2000cc injectors. Car runs like a dream again. As for the leak down I don't know I'm thinking the Pistons might not be exactly at too dead center when I did the test.

 

That's strange to me. Don't the injectors technically seal on the system upstream of the intake valves? But if you werent at tdc then I guess it would slip through the intakes and out the injectors seals? But if that were the case I would assume you'd hear some pretty loud hissing in your face... Glad to hear it's running well again though.

 

^ IIRC the injectors clips were causing the misfire.