Hey, I'm sure this has come up, but I don't have details about a possible cause and I knew someone would have a quick response for me....

I am looking into buying a '94 touring with some upgrades (blitz intercooler, S-AFC, blitz blow off, blitz exhaust) but the guy says it backfires in hi revs and he doesn't know why. Any suggestions??? Thanks

 

Sure, this:

https://www.rx7club.com/forum/search...der=descending

There are plently of threads on backfiring. Just search around.

Good luck!

 

Just did a search, could be related to the air/fuel ratio correct? If so, maybe it could be as simple as adjusting the S-AFC?

 

Backfiring is normal for a Modified FD.

It's due to a "richer" a/f ratio dictated by the upgraded ECU. Richer = Safer(less, chance for blowing your apex seals due to detonation from "leaning out".

 

Not necessarily. Most FD's backfire some after exhaust mods have been done (downpipe is usually enough to get it going).

You might be able to remove a little fuel out of the S-AFC to remove some of the backfiring, however I doubt you'll get rid of "all" backfires.

Most of the time you'll get backfires on decceration which is typical. It can be programmed out on some fuel management systems, but I don't know anything about the S-AFC. If you are getting backfiring at any point other than decceleration then you should at replacing the spark plugs, wires and O2 sensor.

 

why would you want to get rid of the backfires, there awsome especially when you shoot a flame out the back with it.

 

Dude... go to performance tuning shop and have your A/F ratios checked .... if they're in the 10 : 1 region under boost.... let the guy behind you worry bout the backfires....

 

That is totally normal as most people have already mentioned to you. It is due to you running rich in my experiences. On a side note they are totally awesome when you have some ricer honda kid who thinks he is the shiz and you blow a flame in his face. We are the only car that does it naturally and it is beautiful but you dont want to be doing after every shift just go and get the thing tuned and you will love it.

 

backfiring is NOT normal. it might be common, but not normal. bottom line, the car is running rich, excess fuel is getting spit out and exploding in the exhaust. usually, if you are running a stock cat or high flow cat, and can adjust your a/f, then you can tune it so it doesn't bf. a bit harder if you have straight pipes -

 

The Rx-7 run's rich or should be for that matter......which IS normal.

 

I also get backfiring but my airfuel gauge jumps from normal to lean and it is telling me Iam not running rich, so is my gauge messed up or could I be backfiring when lean?

 

If you are using the stock O2 sensor with that A/F gauge, then it really isn't telling you squat. However, you can get more information in the following thread:

https://www.rx7club.com/forum/showth...hreadid=150756

 

Don't think backfire is something you should worry about unless it backfires alot. Look at racecars and also rally cars like the "wrc". They backfire aswell.

 

Anytime I get back home and into my garage and shut off the engine without letting it idle for 30 seconds or so after stopping. I get a little p*p.

I used to worry, but it seems to do it all the time for the last three years.

 

Rob Robinettes site states an interesting theory on backfiring for an FD. He claims it is related to removing the Air pump. Check it out.