Did I just kill my ECU?
 

I think I might have just done somethng really stupid with my '87 TII. I disconnected my battery and pulled out the ECU to look for corrosion, etc. Everything looked fine. I reinstalled it, and made another mod where I added a second ground connection from the boost sensor ground to the chassis (read that this might cure hesitaion problems). I reconnected the battery and tried to start it up. It just cranks - no turnover. It was running real well yesterday and I thought I almost had all my idle/hesitaion problems licked. Now I'm big time frustrated again. I just read another post about holding in the brake for 10 seconds after disconnecting the battery. Is this to bleed the capacitive power out of the ECU? Could I have blown the ECU by not doing this? I tried the ECU checker LEDs and they don't even come on at all when the ignition is turned on. What's the easiest way to tell if the ECU is not working?

Maybe you grounded the wrong wire? I would try reverting it back to stock and disconnect the new ground you made, and see if that works. If not, check to see if you somehow blew a fuse [the ones in the engine bay], but if those all check out, you may have caused something to go wrong in the ECU.

I agree. I would undo whatever you performed, then try again.

Thank, rx7style! The 30A fuse was blown! Unfortunately I don't have a replacement. Look forward to trying it tomorrow.

OK, I pulled the retractor fuse and used it instead. The creature still lives! It seems to run a little rougher at idle than before, though. I guess I'll drive it around some tomorrow and see where I'm at with all this. Thanks everyone for your help with this and all my other problems. If not for this group, I would have given up on my 7 a long time ago and bought a new car. Hmm, now I don't know whether to thank you or curse you ;)

Well, thankfully you didn't scrap your RX-7 because of a blown injector fuse! Glad that fixed the problem, but don't ever ditch your 7 alright? :D

OK, been driving it around for a while now. Since replacing the blown fuse, the tach heads for 0 when take my foot off the throttle (especially with A/C on). If I give the throttle one little tap to bring it back up, it settles in at about 7-800 RPM. Since I disconnected the battery and pulled the ECU, do I need to go through the idle adjust and all that again with the initial set connector jumped? Or do you think I maybe fried a component in the ECU or a sensor somewhere?

It will take the ecu a little bit of driving time to "learn" all its settings and inputs again, Ive found it gets better the longer you drive it, to a point of course. Give it a day or 2. You might indeed wind up readjusting stuff though. FWIW when I did the boost sensor ground it made mine run very rough at anything above 1/4 throttle. I wound up taking my ground loose. Grounding the ecu is a good mod though, just not the boost sensor. I have heard of the boost sensor mod doing well for a few cars though, but not all.