PROBLEMS WITH '01 CAMRY - Please Help

[divine]

I have an '01 Toyota Camry LE [4-cyl].

Recently, the engine light on the bottom right corner of the speedometer window came on, and I understand there are more than a hundred possible problems in the car when this light goes on, from what I've been told. The light is probably a manifestation of one of these [unexplained] problems:

1. When I go about 49 MPH, there is a pulsating "hum" in the car underneath which does tend to vibrate the floorboard a little.

2. Also, when I drive the car from a parked position and go about 5 mph, there's usually one [1] pretty audible hum at this speed that does vibrate the car [just for a brief second]. Then over above the 5 mph the car is quiet - up until 49 mph [the "magical" number] when the pulsating hum mentioned above [in #1] starts.

THINGS I'VE ALREADY DONE:

A.) I just put 4 new tires on 2 days ago - all were speed balanced. So, I can't figure out what's causing these two problems.

B.) I also put a set of NGK Tridium plugs in.

When I let the engine idle in a parked position, the engine itself sounds very smooth.

Could anyone "shed some possible light" on what could be causing these hums?

Thanks so much.

[ASG14]

Go to AutoZone and ask them to read the code (Check Engine Light (CEL, also called MIL for Malfucntion indicator Light), and write it down. They do it for free. The dealer wil charge 1 hour labor for it. Then tell us what it is. That will norrow it down 100 fold, and may give you the EXACT issue.

Also, I do not think the hum has anything to do with the CEL light being on. But we will know when you let us know what the code is.

[marc780]

1. When I go about 49 MPH, there is a pulsating "hum" in the car underneath which does tend to vibrate the floorboard a little.

Did the hum come before or after you replaced the tires? I'd check for: wheels out of balance (maybe the shop screwed it up, wouldnt be the first time). Bent wheel, or damaged tire.

This hum can also be cause by the exhaust system: a leak (you can feel them with your hands, i try to do it with the system cold as it is more comfortable to do); damaged exhaust system, missing or broken hangars from exhaust system and need to put some on. (These are usually made of thick rubber, i'd crawl underneath and look at the existing hangers and the hooks they go on, then look for some hooks with no rubber piece holding them together. Or a broken rubber piece.)

As for the engine CEL codes, i simply bought a scanner from harbor freight for $30, to meit costs less than one time-wasting visit to the shop and alot of times you can just fix the problem yourself if you know roughly wear to look based on the code.
http://www.harborfreight.com/cpi/cta...emnumber=95210