so every scan tool i hooekd to me 90 firebird formula 5.7 tpi would read no data.

i checked all ecm grounds and power and 5v reference to aldl. all wires check ok and all is well.

so today for ***** a giggles i hooked up the scan tool again to see if maybe it would work.

Datastream is what im shooting for but it wont read codes either.


anyhow it did the usuall no data. then i left it in datastream and turned the key off and i say the screeen show me live data for like 3 seconds then went to no data.

so i did it again and sure enoguth when i turn the key to on. then off it blips and data shows for a quick couple seconds.

what im trying to figure out is why and how should i go about figuring out why it wont read data with key on engine running or key on engine off.

I need to get some data to further my diag on the rough idle and crappy 14.9 sec 1/4 mile.

whats weird about the idel is that its at 650 in drive and steady but you can feel its rough and has little to no fluxuation.

humm?

thanks