Well I have been having a stumbling problem i beleive to be ecu related with my old PR4... so i bought a new dizzy, conversion harneses and p75 ecu that had an unknown chip in it so i could go to OBD1... well i test the ecu in my buddies OBD1 CRX with same exact motor as i have and it ran like it was supposed to and seemed to be fine, so i call it good. well tonight i install it all into my car and get it running... well i revved it a couple of times to see if it was being responsive and the ecu was making it run better on my car. all seemed good but i had a bad tach connection and it was bouncing all over the place, well it smoothed out and i revved it... 6,500 6,700 6,800 7,000 7,200 7,500 7,800 8,000 8,500 9,000 9,500 bout that time i realized "oh crap let off" as i did i hear this all to familiar rattling noise and i shut it down... pull plug #2... it was fine #3 fine as well oh i forgot #1 pull it.... it doesnt anna come... unfortunatly i knew exactly what this meant... get the plug out the electrode was smashed in pretty bad and of course plug ruined. pull #4 it was fine. So now i get to pull the head on the motor i havent had in the car for even a full month yet... joy... now i have to hope the head is fine and pray the piston isnt damaged anymore than some very minor dings, then spend money on something that i didnt have to originally cause i screwed up and found out the hard way cause i wasnt paying attention that the ECU chip has no rev limiter aparently.