Recently purchased car ( runabout for the duchess so only does about  30miles a week )

Car done 69K miles and when originally bought it would always start up without accelerator pressure, t'other day it wouldn't start unless about 1/3 throttle applied and now it sometimes starts without  and sometimes needs it,  Cold -warm -hot engine makes no difference.  Other than this  after starting the car idles and runs great.   Onlty work done under bonnet iin last few days was all fluids checked  during which I noticed the uppermost plastic lugs on the battery housing which an ECU locates to was almost cracked through.  I made up a temp aluminium bracket and fastened the ECU through the respective bolt hole with a strong nylon tie wrap.. Please note that I did not unplug the ECU and it was still held in place with the other fastenings.

Everything else on the car works fine 

OK guys..  Is this explainable....  when I did the temp fix on my "floating ecu" I used an aluminium bracket bolted to the body structure which effectively earthed the ECU metal body. this was the only difference from the original mounting, which didn't earth it. In view of this  I decided  to make a new bracket from nylon bar to eliminate the earthing and Lo & Behold the car starting reverted back to it's normal operation  with no other issues.

can't explain it.  If it musn't be earthed I would have thought it would have all that bear metal accessible on show. And if it was earthed when it shoudn't be I would have thought it would not work at all (any maybe damage it).