EM2661

Possible: bad ECM? Bad crankshaft positioning sensor?
Car turns on does this, but when when I drive past 3k Rpms car Boggs (limp mode) sometimes dies on me, battery light on, but alternator is good, all connections are good, and battery is good. isnt the alternator fuse computer controlled? can it be bad ECM causing this?

I did go into limp mode 2x before this while I was redlining (in a hurry to work/school ) but resolved when I reset ECM, now this third time it does this , read on forms it's a bad ECM but before I pay to get a ECM reprogrammed at the dealer would like to rule out as much as possible any ideas ?

ezone

Alternator mounting bolts were left loose and it's gonna fry the PCM (if it hasn't already) if you don't fix it.

EM2661

Not to be rude but how do you know? I actually read that somewhere about these civics, just what to know what leads you to believe that? as i read that i check everything that has to do with alternator, when in and tightens all bolts and reinstalled , same things happens which is why i think its a bad ecm, one bolt was slightly loose, but nothing major, I read that even a slightly loose bolt will not ground alternator right.

Thank you for your comment though, makes me feel confident it was that and now that its tightened i can swap out the ecm without frying it again

ezone

Now that you have the alternator bolt(s) tight you need to see if the current PCM is actually damaged before you bother buying and swapping. You DID tighten that, right?
If the car goes back to normal you save a whole bunch of time and money.

Biggest clue is if the PCM can still communicate with a scanner. If it can, chances are you caught it in time and saved the PCM.
If no communication and the weird screwy symptoms persist, it's probably a goner.