CAMARO6 - View Single Post - Stock Intake Valve Seat Failure on TSP PRC Ported Heads with Big Cam

cmitchell17 · 02-20-2021, 02:08 PM

Last night I got a #7 cylinder misfire and a random misfire code after getting on it hard up to 3rd gear. I was hoping it was a loose plug wire but they were all good after checking. I then plugged a test light in series with the plug and it was good too. I started to get really worried and figured it was valve spring breaking time. I pulled the valve cover and everything looked fine.

I let it cool down overnight and pulled the #7 plug and it looked fine and has continuity and about 5 or 6k ohms. I put a borescope down in the #7 and it looks fine as well. I put a compression tester in #7 and cranked it over a few times and after fooling with my Chinese GDS scan tool to try to put it in "compression test" mode I gave up. You can see the compression tester gage bump up a little when its turning over but it will just go quickly right back to zero. Tried the compression tester on #5 and it did the same thing. I guess I just have to pull all the spark plugs for it to turn over fast enough to actually build pressure on the gage? I believe you should be able to hold the throttle to the floor while cranking and the throttle blade should hold itself open and fuel injectors disable, either way I guess I still have to pull all the other plugs and honestly pulling all the plugs is probably half as hard as just pulling the heads and pulling out the lifters.

Anyway I got the scan tool working enough, so I put the plugs back in and cranked it up and disabled the injectors on each cylinder one by one. When I disabled the #7 I could hear a difference in sound which told me my injector was still good which gives me the very bad feeling I have lost a lifter?

Anyone know what should I do? It looks like its time for me to pull the heads and cam and go for a more reliable lower lift cam.

02-20-2021, 02:08 PM	#1
cmitchell17 Drives: 17 2SS, 8L90, Cam, Heads, E85 Join Date: Dec 2016 Location: US Posts: 1,204	Stock Intake Valve Seat Failure on TSP PRC Ported Heads with Big Cam Last night I got a #7 cylinder misfire and a random misfire code after getting on it hard up to 3rd gear. I was hoping it was a loose plug wire but they were all good after checking. I then plugged a test light in series with the plug and it was good too. I started to get really worried and figured it was valve spring breaking time. I pulled the valve cover and everything looked fine. I let it cool down overnight and pulled the #7 plug and it looked fine and has continuity and about 5 or 6k ohms. I put a borescope down in the #7 and it looks fine as well. I put a compression tester in #7 and cranked it over a few times and after fooling with my Chinese GDS scan tool to try to put it in "compression test" mode I gave up. You can see the compression tester gage bump up a little when its turning over but it will just go quickly right back to zero. Tried the compression tester on #5 and it did the same thing. I guess I just have to pull all the spark plugs for it to turn over fast enough to actually build pressure on the gage? I believe you should be able to hold the throttle to the floor while cranking and the throttle blade should hold itself open and fuel injectors disable, either way I guess I still have to pull all the other plugs and honestly pulling all the plugs is probably half as hard as just pulling the heads and pulling out the lifters. Anyway I got the scan tool working enough, so I put the plugs back in and cranked it up and disabled the injectors on each cylinder one by one. When I disabled the #7 I could hear a difference in sound which told me my injector was still good which gives me the very bad feeling I have lost a lifter? Anyone know what should I do? It looks like its time for me to pull the heads and cam and go for a more reliable lower lift cam. Last edited by cmitchell17; 02-27-2021 at 10:55 PM.