asoduk wrote: How old is the O2 sensor? Have you looked at the air flow meter for wear?
Very, very old. That's actually on the "things to change" list, and I should have done that tonight while I was under it, but totally forgot.
I've visually inspected the AFM, and it LOOKS fine, but I'm not sure how much that actually tells me. The flap moves smooth and free.
Did you get the valves done in the head you swapped?
I had a Suzuki g13b engine that had done the crankshaft keway and had slipped timing just enough to nick the valves. It would run like E36 M3 for 30 secs up to a few minutes depending on how cold it was but then would run fine and had basically normal power.
I could never work out why it was such a pig when cold till I was redoing the engine, looked at the head and it looked fine.
I then get a call from my machinist telling me 7 out of the 8 inlet valves are ever so slightly bent. Just enough to make it a dog while cold but ran great once warm
I pulled it all apart and replaced all the valve seals and lapped the valves while I was in there. Some one had done a 3 angle valve grind on the head at some point, so I just lapped them and they lapped in nice and even, and was obviously making good contact all the way around.
Even so, it ran perfect for a week. If the valves where slightly bent, I'd have probably had this issue from day one.
I'll probably pull the cam tower back off this weekend and see if there's anything obvious and flush the lifters while I'm in there. We'll see what happens.
Thanks for playing everyone, but the correct answer was broken valve springs!! Maybe next time.
On my way to work this morning it dropped to three cylinders all the time, not coming and going like it was. So after I got home from work, I did a compression check, and it confirmed what I already knew from listening to it. One dead cylinder. It did let me know which one though, so that was helpful. I pulled the intake to find that #4 intake valve wasn't closing all the way. Then I pulled the cam tower to find several broken valve springs. Like, almost all of them.
When I put this head together it had been sitting on the shelf for a while and had some minor surface rust on the springs. I soaked them in vinegar, then degreaser, and they looked as good as new. I guess they had been significantly weakened. Whoops.
You'll need to log in to post.
