bee

93touring..

What would cause minor backfiring(more than normal) during rapid deceleration. Also what does detonation/knocking sound like, what are the signs..
Motor only has 30k on it, im sure its not knocking, any help would be appreciated..

btw..
mazda south screwed up my hoses and the wastegate wasnt opening. hit 15 psi one time.. I re-did the hoses my self and now I get the perfect 10-8-10. Only went over the stock boost levels one time so im pretty sure I didnt blow anything. The car has no mods other than a cat back and a turbo timer..

bee

^

P'cola FD

rotaries run rich on decel, and the catback lets you hear it.

Mahjik

iTrader: (1)

Bee,

If you have a downpipe installed that replaced the pre-cat, then you will get some backfiring. Now how much, that's another thing.

I usually only have backfiring during deceleration. If you are experiencing more than that, you might want to check and see when the last time your spark plugs were changed as well as your O2 sensor.

As far as detonation, I've heard it described as popcorn popping in the engine. However, they say it's usually not heard from inside the cockpit.

jspecracer7

My old ECU backfired like CRAZY before I retuned the fuel on decel with an S-AFC. A buddy of mine could hear it when he was in FRONT of me!

93TTRX7

all it takes is for the car to detonate once...there is no way you can survive a detonation

jspecracer7

That's BS. From personal experience, my FD was detonating before I had my datalogit. I knew I was detonating because I would do the run, hear it, and then when it was over, I would see readings as high as 100. Once I hooked up the datalogit, and could see what cells I needed to add fuel to, I retuned fuel/leading and trailing timing, and now my knock sensor NEVER reads anything over 25...unless I hit a pothole in the road or something.

My friend(FD Okinawa) had readings as high as 200(T-04R) before we figured out his RRFPR wasn't set high enough. It was knocking like that for over 2 months. Once we realized what we did wrong, we fixed it, and redid the fuel map, and now he reads knock readings around 50.

SilvioRX7

My engine detonated once and the sucker blew.

93TTRX7

very rarely anyone survives detonation...you got 3mm seals? even with 3 mm's constant detonation should destroy it...maybe your fd is on steroids or something...if everyone's motor was that indestructable who'd want a supra?

skunks

how did you retuned the fuel on decel with an S-AFC? did you use the the Deceleration Air Flow Correction function (cuz i though that was only for hot-wire air flow meters type cars and ours are pressure) or did you just lower the high/low fuel settings?

jspecracer7

two words...un-lucky...

I feel for ya Bro!

jspecracer7

Stock Engine for me. FD Okinawa's engine was street ported/exhaust ported, but the internals were stock. That whole 3mm debate is CRAP. Machining the rotors to fit 3mm seals is worthless unless I want to reuse them. Either way, 200 on the PFC knock reading HAS to be detonation. He had that for two months like I said, and then we fixed it. The manual says that 50 knock reading is not necessarily detonation, so that's what we stuck with.

We all know(as rotary owners) that these engine's are far from indestructable. But they can take some beating. Not much...but some. I am VERY careful with my engine, but I rail on it every day. I set my exhaust temps low, watch my PFC for any abnormal readings, and LISTEN to the engine for anything unusual. Maybe the Pope put his blessing on my engine so that it won't blow(but still knocking on wood).

jspecracer7

Deceleration AFC is only used for maf meters. I lowered the low throttle settings.

maxpesce

Old Plugs will also cause increased AFTERBURN - Mine was poping 5-10 times every time I slowed to a stop but now that I put in new plugs it hardly does it all except when chopping the throttle from high RPMs.