Long story short : Hit a bump and car died, whenever you try to start it while cranking over it backfires LOUD and wont start


full story :

ok so this is a friends FD

hes had this intermittent problem where the car will just randomly start backfiring and losing power, then he says he usually downshifts and its fine, and mostly happens when he hits a hard pothole or bump on the road

Well the other day we checked his plugs , the leadings were quite carbony and black, trailings looked okay no carbon buildup, less than 2,000kms on these plugs so we cleaned them off and put them back in, car run perfect for 2 days

then today he said he hit a huge bump on the road and the car backfired like a **** , he pulled over and said he heard almost like a vac leak, boost gauge was sitting at -10 and then car died

when he tries to start it now the car backfires LOUD and does not start, sounds like a broken 2 step lol a cop actually just came because they got reports of gunfire, whatever his intermittent problem is now its constant, any ideas? all the wiring for sensors and what not look okay.

car is a 93 jdm fd, with a power fc commander installed here, and single turbo if that helps.

 

Something came lose when he hit that pothole, check map sensor?

I thought we have a lot of pothole in Chicago, guess Vancouver isn't that much better.

 

Haha vancouver is a city of potholes basically. Especially the suburbs here so much road work everywhere

Found the problem as i was taking a video haha. A vac line popped off on the upper intake mani. Soon as i plugged it, ran perfect. Never knew a vac leak could make that big of a issue on a fd!! Got it running before i Found the issue and it sounded like the motor was blown lol backfiring very loud while idling.