Fellow Camrymen,
There was a loud `pop' or little `boom' then smoke from under the
hood on startup this morning & I was @ a loss where to continue the
search.
After recovering from the initial shock, getting out and opening the
hood, I began to look @ driver side corner closest to me, where
smoke seemed concentrated, also checking fuses but nothing was
present or obvious.
I then realized with strong winds swirling, where `it' began could be
different than where smoke appeared.
It started on 1st try w/out any obvious leaks, smells, smoke, etc. so after revving it awhile, gauging the blue smoke to be slightly greater and not definitely related, I drove about 30 miles and returned home.

I did notice a prominent rhythmic electric `click' mostly linked to engine speed, but which was not entirely constant.

Past history has seen several alternators/batteries(former owner),
which I found were due to incorrectly installed car alarm. This battery
& alternator were swapped from a parts car, and were strained also.

A search has me focused on the ignition coil, leading to several ?s:

> Did I possibly do any other damage driving w/ the bad(?) coil ?

> Do coils go `bad' gradually, or all at once ?

> A followup thought; might it be linked to my bad cat/EGR valve...
I did not get any specific smells , due to the wind unfortunately.

Thanx for any assistance
JMCamry

Could it have been a small backfire through the throttle-body and air filter? It is possible with an older car. How many miles do you have?

As far as your questions, I had coil problems on my 90 Camry and they went bad gradually. I had to replace them at about 75,000, and again about 145,000. I don't know if that was just my car or if it's common. I don't think you'd do any damage driving with bad coils, but the power and performance suffers. I noticed a real lack of power climbing hills when mine were going bad. A bad one might cause a backfire, too, if it was a weak spark.