What can make a motor detonate? Other then the obvious lean conditions and spark advance. My motor started detonating a few days ago. Really bad. I changed the timing belt yesterday and set timing perfectly. Checked a/f ratio and it's perfect. What else could cause this? I mean it's so bad that it won't tach above 3k. I can't even press the accelerator under load or it sounds like a freakin box of marbles rattling around inside there. It's a perfectly healthy motor otherwise with low miles. I don't understand. Someone help please!

 

shitty gas

 

also, check for boost leaks. My DSM did the same thing when it had a boost leak

 

I think i'll try putting some premium in it, but it's the same gas I've been using all my life. Maybe I got a bad batch. Thanks.

Could it maybe be spark plugs?

 

possibly, yank those bitches out.

 

replace the cap and the rotor

 

Did you do a head swap or MPFI conversion?

 

whats the last thing you did to it before it started detonating?
also, are you sure its detonation? greengsxinnova said it sounded like his was detonating, but it turns out he spun a bearing.

 

yeah if you can post a pic of what they look like we will at least be able to point you in the right direction.

 

Yeah they're definately not looking good, they're covered in black carbon deposits. I just bought a new set I shall install tomorrow. I'll take a pic of the other ones if they don't fix the problem.

It's definately detonating, not rod knock lol.