Hi guys, Noticed in the last couple days that my Z (1990 manual NA) has had a rattle from 3000rpm and above under load. Only on acceleration, not on deceleration or when maintaining engine speed. Performance seems to be normal but have limited going above 3k until it's diagnosed Datascan shows no error codes, everything looks normal except the TPS has .36 instead of .45. I've known that for a while but stripped the bolt :bash: Thinking VCT rattle?
Rattle under load?? So can you free rev it up to 6,000 with no rattle? If so your detonating, pinging, pinking, lots of tiny little cluster bombs going off inside your chambers, etc. Really should find out why. Usually a bad fuel batch for an NA, especially if you det sensor has been bypassed.
Sorry, I meant only while increasing engine speed. So if I free rev past 3k it rattles the same as it does if I rev past 3k while driving. Seems to be coming from up top under the plenum somewhere, but I'm not too sure. Not lifter tick, though it's had some lifter tick for a while intermittently on the rhs bank. Not sure if it is detonation and if so I only run it on 98RON from busy servos so shouldn't be stale fuel. Might have water in it, or something? I did wash it the day before I noticed the rattle and my filler neck is not secure. But would it be rattling at 3100rpm and not 2900rpm as it is now if it were detonating? Any checks to rule out vct?
Detonation will be load dependent, not RPM dependent. You could try disconecting the VTC solonoids. They are the ones with the nylon sleaves on the connecting wires. Might make a difference. If it's only apparent at 3000rpm onwards, then it sounds like it's only when the cams are advanced. So disconnecting them might rule it out...maybe.
I'll try it in the morning before I drive to work (60km of reasonably quiet highway) through the rev range. Filled up with almost a full tank of 98 from a different servo so that *should* rule out fuel. I'm beginning to collect parts for a rebuild anyway, might be sooner than anticipated...
Forgot to mention det sensor is NOT by passed. It's plugged in, and shoeing code 55 spun bearing keeps creeping into my head too but I really hope not. Doing the build and swap now will kill my wallet
