Detonation?

[laqn]

What's wrong with my car: when I start it, there is a big pop, just once, sounds like detonation. After that it runs fine. Happens only when the engine is warm. It's a 94 V6 1MZ, (auto). Thanks.

[Luckynumber5]

DEtonation is quieter than you think, a big pop isnt very descriptive either. Does it come from the intake or the exhaust? Does the car smoke at all when it happens?

[toyomoho]

The fuel may be igniting in the exhaust system. Too much fuel (cold start injector on), hole or leak in exhaust system. Not sure what effect this would have on the CAT.

[laqn]

Originally Posted by Luckynumber5

DEtonation is quieter than you think, a big pop isnt very descriptive either. Does it come from the intake or the exhaust? Does the car smoke at all when it happens?

It's definitely coming from the engine, not the exhaust or intake. It sounds like dieseling, so that's why I thought it was detonation. Anyways, one metallic/dieseling-sounding knock on start up.