Hi all, I just got this 93 RX7, got all of the cooloing system repaired, but now it runs extremely rich and won't clear out and of course now it won't start. I put in new plugs and it started right away and immediatly went to rich and won't clear out. Any Ideas. Oh no check engine light. BTW, I looked for this same topic till I couln't see straight so I'm posting it, hope some one can help. Thanks

 

Check your O2 sensor

 

Thanks, will do!

 

O2 sensor replacement can often help with 3k hesitation too. Let is know if it works.

 

Even with the o2 sensor going out the car generally wont be rich enough to foul the plugs. Are you running the stock ecu? You might also check the MAP sensor, which is mounted on the drivers side firewall and has a vaccum hose attached to it...or should. Other reasons of running rich could be a stuck or leaking injector.