The car does not start

Will the starter crank? One possibility is the security system. I'm not sure what you mean about computer not showing anything? If you used a scanner that showed live engine data, it should have showed plenty. If you can't communicate, maybe something wrong with the datalink connector?

Scan for codes and check fuelpressure with a gauge auto parts rent them.

Those are both converter problems could be the converter or an O2 sensor or an air leak in exhaust before converters. Have a pro scan it as he can check to see if it's the converter or not. But it's probably the converters are bad. It's about $415 for both converters which you will need at rock auto less shipping.

Likely check fuelpressure as well though. Auto parts rent the gauge.

Hi, If it cranks good but won't start, when the problem occurs, have a helper crank it, while you visually check for spark at the plugs. If you have spark everywhere, use a gage and check fuel pressure. How long since a tun-up? You need to test when the problem occurs.

Did you ever get a chance to do any testing?

Ok--i reckon you don't mean "no spark" (associated with turning over and no electricity thru the spark plugs)

The way i read this is, when you turn the key to "start" absolutely nothing happens.

Please read my answer in this link.

I am assuming that the wiring from the key down to the starter relay/ solenoid is good,

And the neutral safety switch is good too.

Http://www.2carpros.com/questions/1999-chevrolet-lumina-wont-start

If this does not help, return and we will continue.....really give it your all. There's nothing like going thru a million motions, and finding out it was something overlooked days ago

Return with a voltmeter, someone on your end able to use it.

The medic

Missed that--has the battery been tested?

Headlights work good?

The medic

Drop the starter motor and get it load tested-sounds like the overrunning clutch is slipping-