09-03-2008, 10:34 PM
Join Date: May 2005
Location: Edmonton Ab, Canada
Total Cats: 8
KNOCK knock!! Sticky valves?
So my engine began knocking real bad this past week..
I thought I had gotten a bad tank of gas after filling up in a remote farmer town (pump said 91 lol) and after emptying the tank and refilling with 94, twice, I still have the problem.
Backround; I've been running on mspnp for a couple weeks with zero kncok issues.
22deg timing in boost above 4k (7psi) 12:1 afr in boost, 14.7-15.5 in cruise
Nothing was touched before the knocking started..
Engine has two stuck intake valves in 2/3 and bad rings in 1(15per leakdown) and 7per in cylinder 4 as per the leakdown/comp test done last month.
Anyway I'm only getting the knock out of boost, either light accel low rpm(2-3k) or cruising at 4k, as soon as I go into boost no knock. I was addvised that the sticking valves could be a likely culprite, seeing as I've changed nothing but the oil in the last while I'm almosy convinced its a mechanical issue. Oh ya I have reloaded the base mspnp file and tried to tune it all over again but the kncok is there even with 15deg timing at 55kpa and 12:1 fuel, crazy right?
Ofcorse I have a race on the 20th and need the car tip-top by then. I have a 99 head w/o cams at home that I was going to put on if the 94 cams are transferrable (I believe they r but don't know for sure). And yes, I know the 94 cams suck but unless I can find a 99set asap for a decent price its all I have..
Soooo, could sticking intake valves cause knock (overheating valve as the knocking goes away when the boost hits..)?
My cheap quick head build consists of new guides, head studs and gasket, maybe springs since I have to disassemble the old head for cleaning first.
Any recommendations on more stuff to do or what could cause the knocking, no msq files as I'm on my blackberry, sorry for grammar or spelling errors also.