Ok I have been around /worked on many fc's before all with smog **** removed, yadda yadda and the one constant factor all of them shared was backfiring and shooting flames in high rmps.

Well i just brought my car home, i got the engine rebuilt with everything brand new from mazda except the actual rotors and the e.shaft. Well My license is suspended and i am not gonna insure it till january when i get my license back so i am letting it run a bit every day in my garage to help everything settle. SO i figured i would see how my bad my new baby backfires so ill know not to be caught off guard and.....nothing.
Its been a couple weeks since the engine been installed so i figured it wouldnt be horrible for me to rev her a bit. I brought her right before 7grand several times and back but no backfire whatsoever. I have straight 2.5 pipes and no cats. I know backfiring is bad but i kind of miss it. It feels good to rev so high sooooo smoothly but the flames are like a 7 trademark.
I know im not running lean becasue i had that problem when the engine was first installed an it was fixed with a new harness and injectors.Plus n/a's notoriously run rich.
How should i feel about this?? And why wouldnt my car be doing it? is something wrong here? Is it just the rebuild needing to break in more? Any ideas?
<shakes head>

 

Haha! Thread jack! I have a qustion about backfiring on a rebuild to throw in here. How long will it backfire? The engine has about 3,000 miles on it now. I have cats removed so is it going to continue to backfire?

Sorry bout the threadjack!

 

I have the same 'problem...'

Before my rebuild it backfired like crazy, and now with a streetport with cleaned/balanced injectors it rarely backfires unless its been running for about an hour or driving "hard." The engine only has about 500 miles on it and i've been shifting at or below 4000, so maybe its just not revving high enough to backfire...

Its not really a concearn of mine, but i'm curious.

-Andrew

 

You see me and you ^^ have opposite situations. Yours is backfiring too much and mine isnt backfiring at all. Im not sure I ahve a problem, just afraid it may be a sign of a bigger issue. Mine only backfired in the beginning when i needed starter fluid to fire her up.

 

Why would it be a bigger issue? A backfire is simply unburned fuel igniting due to the heat of the exhaust. Lack of backfiring means lack of unburnt fuel exiting through the exhaust. I don't understand why you would be worried.

 

Well considering that n/a's are known to run rich and backfire lack of backfiring could mean a few possible things according to common sense

1) everything is in perfect harmony

2) lack of fuel, possibly a secondary injector issue

3) who the **** knows

It just makes me uneasy knowing that every fc (approx. 10) I have ever come in contact with backfires (including this one before the new engine) and this one does not. if this is a good thing then I appreciate it but i was just tryign to rule out any possible problem that this unusual behavior can be a sign of.

 

I was actually wandering the same thing about my car....except mine was after I swapped in my Jspec TII motor, and it don't backfire anymore, and it shot killer flames before, all the time. and also I know mine is running super rich, since it won't even come close to passing emissions...

so...bump for this thread! hopefully there's no problems here.

 

How many miles on the rebuild? Because if its less then 1500 you should be taking it easy on the motor till its broken in.

 

It backfires better when you let off the gas suddenly after being under load. Under load it's shooting more gas than in neutral at the same RPM. Mine only backfires if I hit the rev limiter in neutral (not recommended) because it gets more gas at a high rpm and the rev limiter cuts the fuel very suddenly. It seems that when the throttle is abrubtly closed is when the fuel gets "stuck" in the exhaust. There is some trick about revving real high and shutting the engine off and then turning the key back on on the ACC. (NOT START!) position before the revs drop but I don't want to backfire bad enough to do that. Just let it backfire when it wants to. Bad spark plugs help too.

 

Ya know, I thought for sure that after I opened up my exhaust (got rid of cats completely) that it would backfire nicely. It didn't for the longest time then all the sudden it started backfiring like crazy and not running right.

Hooked up a loose connector and it won't even backfire if I hit 8k under load then let off or shift hard. I dont' get it. Seems it's getting just the right mixture to not backfire.

I'm not gonna complain, but you're right. Those of us without flames always seems to feel like something's wrong.

 

how come i aint shootin flames out. i have an NA with gutted cats, and a nice single exhaust, i mean it pops but it aint shootin flames. I WANT FLAMES! hehe. but yes, what is the problem?

 

Why are you revving it up to 7k right after it's been rebuilt and you just got it back in your car?

 

Thats what I was wondering. I guess you can do whatever you want to your own car. I know that when I get my rebuild done I'll be babying it for quite awhile.

 

Don't do this. Either drive the car, or don't. A few minutes of initial idling are enough to bed in the seals, but the actual breakin should take place with the engine under load and at operating temp.

Which means that your emission systems are working properly. The exhuast probably isn't hot enough either.

If you had new bearings installed, DON'T do this. You need several thousand miles before they get to the point where you can take the engine to redline.

No, there's nothing wrong with your car. As long as you don't break it.

 

It has about 30 miles on it and the builder told me to let it run a bit every day. I had it running for almost a half hour before I started gently raising the rpms till around 6500 and then let off. I wasnt mashing the gas or anything. Ill just let her run idle a bit every day from now on until i can drive her again. Meanwhile i have some electrical issues ill tend to rather than worryign bout this(headlights wont pop up, Fog lights dont work) I gotta try to work with one hand seeing how I cut my fingertip off my right ring finger yesterday and got ti reattached, my whole hand is bandaged up. Talk about bad timing.

EDIT^^^bout the emmisions^^^ I have none, no cats, no air pump, nothing.

 

You're an idiot. Do you even know what the break-in procedures are? At a BARE minimum you need to give 1500 miles to it without going over 4krpms and then 500 more GRADUALLY increasing the revs to redline by 2k miles, with oil changes at 500 and 2k miles. This doesn't even include if you have new bearings, which will probably need more to be safe. 30 miles does not justify going to redline, and even if you "gently raise" the rpms to 6500 that means ****, 6500 rpms is 6500 no matter if you mashed it or gently raised it.

Hope you didn't do any permanent damage...

 

OK, im gonna look for a writeup on breakin procedures right now. What kind of damage can be done that way? It was only that one time and now i know better so i wont be doing that again. Thanks for the warning. I am unclear what your referrign to with bearings but i assume i got them considerign the only thing kept form the original engine was the rotors and e shaft.

 

Here are two.

http://fc3spro.com/TECH/FAQ/breakin.html
http://www.rotaryresurrection.com/ro...r/breakin.html


Damage? Seals warping/breaking from not being fully seated, seals not seating properly, etc. I don't know what would happen to the bearings because I haven't replaced mine or looked into it, but I'm sure it's something like warping.

 

The point is not HOW you get to redline, it's just that you SHOULD NOT!! You're going to detroy the engine if you keep running it about 4.5K without letting it break in! What the hell?? This isn't even rotary specific ANY rebuilt engine you need to take it easy on!!

 

You're wrong. With lots of piston rebuilds you run it HARDER for the first few hours after the first startup to accelerate the seating of the rings and ****.

 

Please keep it friendly....No reason for insults. I think he knows by now the error of his ways...

 

Sorry, been a frustrating past couple days

I just hate to see people ruining a basically new engine. Besides, being nice and friendly may not get your point across always, or they might take it lightly, being rude and abrupt will make them pay more attention to what you're saying

 

Take a deep breath, and go visit, '"Resurection of Thong Thursday"!
ahhhhh, works for me!

 

Its ok i totally understand now and i will be paying close attention to the breakin guides I was linked to. It seems to be running fine as it ever was, Ill just be as more careful now and hope everything is ok.

 

How come when tuners rebuild your motor and don't have time to put thousands of miles on your car before they dyno just let it idle for a while and drive it a couple hudred miles, then tune the car with less than a thousand miles on a completely rebuilt motor, redlining and boosting several times? I would like to know this since I have been in this situation before and will be again in the future. Also, the most important thing is to baby the car, watch all the gauges and frequent oil changes but some tuners recommend "stretching" the engine out to a high rpm only every once in a while so the engine seats in all positions of it's future operation? I am curious