Why does my rx back fire when I let off the gas to shift? I know the timing is right I used my dwell meter to set the timing angle. Please help??????///////

 

all rx-7s backfire... its mostly because of all the unburnt fuel and crap that gets out the exhaust and the exhaust temp... our exhaust temps are alot higher than piston engines.. so especially if you shift after 5k you will get back fire..

 

Welcome to the wonderful world of rotaries.

 

What do you have on the car? All Stock? Any bolt ons etc?

 

Mine is all stock and it will back fire in 1st gear

 

might as well get used to it its a rx thing!!!

 

weak ignition and rich mixture will make the backfiring worse, further modifying your car will make it impressive. check to see your air pump and anti-afterburn valve are in place... these will keep you from shooting flames somewhat.

upgrading to the direct fire ignition system and leaning out your mixture might (logic - no experiance) help keep the pow's down.. but i personally love it. my rx (RB header, 2.5" exast, two chamber econo muffler) shoots foot long flames from the tail pipe when im racing...

 

yeah its really a first gen thing. but if you want to minimize it go for a direct fire ignition. It helped me alot, now I only backfire a little after takin it to redline a few times in a row. 2gcdfis Theres my write-up on installing a 2nd. Gen direct fire ignition. Cheap and easy mod, and not only will it reduce backfires but you'll get more power and better fuel efficiency (instead of going bang in your exhaust the gas will go bang in your engine )

 

Thank you very much. It is over 5k when it backfires. So, everything is as it should be! Thanks for your replies.

PS--it's all stock.

 

If your car is still all stock, it should not be shooting flames. Start by looking at ignition, trailing, timing, A/F ratios, AAV, air pump, and check to see if the cat is gutted.


I take it you haven't spent too much time in the 2nd gen section. The TII's can make us look pretty lame when it comes to flames some days.

 

Leaks in the exhaust system = backfiring

 

i have a leak in the small pipe that goes back from the first exhaust pot to the engine and mix' t there somthing,now i have backfire when the engine is coold

 

hmm, i wonder if you could use theold "one way" valvle from the air injection system to selectivly introduce air into the exaust, so flame shots could be bigger with it open (assuming another, fixed valve is attached) and smaller (or not at all... officer) with it closed

 

true, I havent spent ANY time in the 2nd gen section. Do they ever shoot flames stock though? I didnt think a relatively stock fuel injected car would, but I could be totally wrong.