I don't know if this is good for the car or not, but the car shoots 3-ft. flames and it constantly backfires from 4k-6k rpm. What's wrong with my car?

 

Running without a cat requires some attention to tuning and boost levels.

Wait, did you install just the downpipe, or did you replace the main cat as well? What other mods do you have?

Dave

 

be careful. sounds like you are at risk of blowing an engine.

 

lol, stop watching F&F.

 

All I have is an exhaust and downpipe. I removed the cats. The damn car sounds like a popcorn machine and is not building boost at all.

 

OK, so a stock ECU, stock boost control, and you have an aftermarket downpipe and midpipe. That is a very bad idea if you're not certain your boost levels are still under control. Have you taken it out on the road yet, or is what you're reporting just the first start in the driveway?

I'm gonna hope you haven't already blown your engine. Does it idle ok? Do you have a boost gauge?

Dave

 

Yes you are correct, everything is stock except for the downpipe and exhaust. The first drive was amazing; pulled really hard, but after that everything became crappy. The car idles fine, but will stall at times if I rev the engine. If I go WOT, the whole car sputters; kinda like its hitting a rev limiter. The turbo doesn't even spool. Or if it tries to, its like the ECU is cutting the fuel or something. Man I hope its not blown! No boost guage btw.

 

Uh, ohhh... that doesn't sound good.

 

dude you popped the engine

 

Did your car stall by itself before??

 

Yep, I bet its blown. Read the FAQ and then take it for a compression check. At least be smart enough this time to take it to a rotary shop for the rebuild and new turbos, because dealers are stupidly expensive and not good.

Dave

 

ouch...

 

get a boost guage.. well, vacuume really... check howmuch vac you are getting at idle... if its anywhere above 10 and stable, its ok... it should really be at around 15 inHG.. if its stock.. but if your getting vacuume thats not holding well or jumping all over the place, its blown.. also, by the way that you described it, i think your motor is blown.... you probibly detonated on the first run.. and blew or chipped an apex or side seal... an easy way to tell is take out one of the spark plugs and crank the engine... the noise should be equal... it should pump out air in equal sounding patterns.. if you get a high, low low on either the front or the rear rotor, the motor is blown... thats the faster way of knowing it until you get a real compression check

 

I didn't intend to put you down here - but there is a truth with RX-7s, where a few things that seem logical aren't.

1) The bolt-on mods that you can buy cheaply, are not as simple as bolting them on. The midpipe is extremely dangerous without proper boost management
2) The Mazda dealer would seem to be a safe place to take your car - it's not.

The bottom line is you must research every thing you do on this car before doing it - the simple answer is sometimes very wrong. Some people come in here, ignore the warnings, and blow and engine or wreck the car doing something stupid. If this is your first time dealing with the special character of the FD, you can't be blamed. But from this point on it's vital to follow the collective knowledge and do extra homework.

Dave

 

Oh man I was hoping the replies wouldn't lead to this!! The idle is fine; it sounds normal, just a bit louder due to the addition of the downpipe. The only time it stalls is when I rev standing still; just to little over 1k rpm, on its way down. I mean the temperature level is fine and the car drives. It's just that I can't build anyboost because it "knocks" I'm gonna get this checked out. Damn man, I never knew something like this can happen with a simple mod! Thanks for your help guys!

 

Don't assume your engine blown! I know everyone on here is saying that it might be. But I had all the signs of a blown motor and it turned out to be a stuck side seal, which most of times you can rev them back out.

 

I thought their were no worries if you just add a downpipe plus catback, with the stock ecu. My only performance mod is downpipe and catback, I should be fine with everything else stock right, accoring to the 3 mod rule?

 

The fact that the engine idles fine is a GOOD sign. If they are blown BAD they won't idle without extra gas if at all.

 

Generally yes it's ok. (Although the 3 mod rule is falling out of favor vs. the 10psi rule).

Adding a downpipe and midpipe together are a much bigger step - the elimination of both catalytic elements can lead to much higher boost that the stock ECU isn't programmed to handle. If I understood Importuner correctly, he has a downpipe, midpipe, and cat-back - which can often be trouble - and is an unknown danger without at least a boost gauge to monitor the boost level.

Dave

 

Well he should of read the forums, it is common knowledge, if you add a aftermarket mid pipe than you are going to get boost spike.

 

If "common sense were common, everyone would have it" guess this could be said for common knowledge too.