Poppin sound after high rpm decellaration. Should I be worried?
 

Hey,
anyone that was at the Fuddruckers meet today, did you guys hear that popping sound when the I zoomed out of the lot. That didn't sound to good.

It's also happened another time after driving at high rpm and shifting gears.

Anyone know what that was and what I should do about it?

Thanks,

Later

Sebastian

probably a backfire :bigthumb:

what about the sound when you almost hit that lady. :P

it's probably just running rich so the extra fuel in your exhaust is popping...

or hitting ladies will sometimes make the same sound...

if you don't have any cats, you might get some good flames :)

Ignition breakup?

Hey
I just got my 3rd gen a week ago. I don't know too much but I want to learn.

So whats ignition break up? What causes it? How do you fix it?

Is backfire just if its running rich and eventually just ignited in the muffler or something?

I guess if theres any extra gas in the muffler it would ignite after driving at high rpm since everything is extremely hot.

Its wierd that it would be running rich. The ECU was Remapped by Rotary Performance professionals after all the mods.

Also it has a Apexi Air/Fuel Controller. So wouldn't that take care of mixing air fuel properly?

Thanks guys

Seb

yours was the FD right? I don't know about FD's, but I know that a lotta times FC's will do that normally....

When you lift the throttle really fast sometimes the computer can't react fast enough and keeps injecting fuel... the rx7 FC's had some solonoid trickery to help burn off that extra gas (dash pot, and some others, AAV maybe?) but they never completely worked, and especially not when lifting throttle at high revs. Every FC I've ever heard does what you describe on a quick throttle lift. (I haven't heard that many though :p: )

I also don't know what systems the FD had to try to keep this from happening. I know jason's FC 'vert with the megasquirt doesn't do this as bad though, I'm assuming b/c the map sensor reacts a lot faster than the stock AFM to the throttle closing.... that and we have the low load part of his map set fairly lean, and have the MS set to cut some fuel based on the TPS.

some times they set it to run a little rich just so it doesn't run too lean and blow up your engine.

yeah if you had it retuned it's probably running pretty rich.... lean conditions kill turbo engines... it's better to backfire a bit than blow the engine.

Ignition breakup I've only seen on NA RX-7s. (FCs)

If it's an FD, and a single pop, it's probably a backfire. What kind of exhaust does it have?

Dave

Well that's good info guys. Appreciate it. I'm glad its running a little rich than a little blown up.

Well heres a list of what its got. What do you guys think I should put on it next?


Steering Column Mounted Pettit Racing Boost Guage
Apexi Dual Intake
GReddy FMIC w/ custom piping
GReddy Elbow
JDM Efini Y-Pipe
HKS SSQ BOV
Apexi Air/Fuel Controller
GReddy Boost Controller Profec Type S
Remanned Stock Twins Non-Sequential
Remapped ECU by Rotary Performance
PWR Racing Radiator
Hose Techniques Silicone Hoses
Pettit Racing AST
New Yellow Top Battery
Rebuilt Transmission same time as engine (5 Synchro taken care of)
Bonez DP
Bonez High Flow Cat
GReddy Catback
2-Way Viper Alarm w/ Pager

and a smashed backside. DAM YOU RANDOM DRIVER!

Seb

What boost are you running at?

If it's still 10psi, then the ECU would def. be rich.

Dave

Yes, I believe it is. Should I raise it. I guess its about time I figure out how that boost cotroller works.

anyone?

not to be a dick, but there's probably A LOT more information in the third gen section

good luck bro, enjoy the 7 :bigthumb:

Popping on decel is pretty normal for modified FD's especially ones with a close to wide open exhaust...

Do NOT just go raising your boost because you think you have the fuel / mods to support things unless you have $3-$5,000 laying around to put in a new motor.

Only way to really figure out if you have the fuel / mods to support more boost is to hook up a wideband and see for yourself.

Tuning is better left to the pro's. I've figured out how to do a lot of things over the years with my FD ( with the help of some friends ) but tuning is something I would never even attempt.

What color / model / year is you're FD? I've seen 2 this week around here that I have no clue who they belong to...

It's red stock exteriour w/ polished stock rims.

Any suggestions for what my next mod should be?

Were you on 97 with it Friday morning? I saw a VR that was essentially stock and no wing on there maybe between 8-8:30 am...

Maybe get a good ECU ( a remapped ecu has limits ) and definitely get it tuned before you do anything.

No I don't think that was me. I'm usually not up till 12 on weekends.

Really what do you mean by limits? What are some advantages of the a new ECU. I hear the FC Commander is good. Would that be considered an ECU or just fuel management?

Any suggesting on places around here to get it tuned?

Thanks

Seb

I disagree. You can learn a huge amount by tuning your own engine. It'll bring you to a whole new level of understanding. Especially if you use the Megasquirt :bigthumb:

I can honestly say there are TONS of people out there that tuned their own engines, boosted or not, with megasquirt, and all of them are extremely knowledgable about how their engines work, and about tuning theory because of their megasquirt experiences. Most of the people who work on/use megasquirt are not pro tuners; but have still managed to get very good results from the megasquirt at a fraction of the cost of one of the more expensive ECU's; myself included..... tofuball's install isn't done (still prototype and messy) but it runs great. Once he gets his transmission install done, and his new intake (so we can put in a proper air temperature sensor) and gets his fuel-pump issue taken care of, I'll update his firmware to include the trailing ignition fixes I made, and we'll do a final tune, and dyno his car...

The point is, as long as you're careful and do your homework before attempting anything, tuning your own engine is fine.... and you'll learn a huge amount in the process... If you have a lot of money to blow, and don't care how anything works, then I recommend letting someone else do it for you.

Umm, you realize he said he had an FD right? And that I was talking about tuning an FD right?

A real ECU is for tuners, Megasquirt is for people with much less experience as you mentioned. I don't know of a single FD owner that's using MegaSquirt and there IS a reason for that.

Plus doesn't the MegaSquirt only do fuel only for rotaries? and have no ignition control?

Yes, I realized that.

Megasquirt is a real ECU, it does fuel, ignition, extra outputs, etc... all the same stuff that your "real" ecu's do. 13Beast REW is going to be using megasquirt to tune his FD.... The only "reason" nobody has used it on an FD is because the ignition code for rotaries only recently became viable. That and ignorance.... everyone just heard (as you probably did) that megasquirt is fuel only, and stopped thinking about it there.

It's not FOR people with less experience... but it IS a good learning experience for those who have less... There are pro tuners running these things too, I recall one guy on the megasquirt forums running over 1000 hp although I'm not sure of the details (aside from the fact that it wasn't a rotary). At this point it's not for those who want something easy or plug 'n play, but that's why you learn so much.

Fairly soon (tomorrow most likely) I'll be writing up a configuration guide for rotary engines using the MSnS-extra firmware (With my bug fix for trailing, and my code for FD trailing) for those who want to try it out.

Megasquirt in stock form with the standard firmware is only good for fuel on ANY engine... BUT... with the MSnS-extra firmware, there is a huge list of extra features including: Staged injection, fuel/spark based rev-limiting, Overboost protection, AFR table (use with wideband O2), traction control, overrun fuel cut, and the big one, the toothed wheel decoder, which can decode up to a 60-2 wheel, and includes support for the Denso style 12 + 1 wheel. (or 24 + 2 on the FC CAS, which is really 12+1 since the CAS spins at half e-shaft speed)... also included are: up to 4 extra outputs for things like aux ports/VDI on an NA 7, which can be actuated based on RPM, coolant temp, or almost anything else the megasquirt keeps track of, launch control, boost control, etc...

The only thing is for some of these features, extra circuits need to be added to the megasquirt, which is pretty trivial.

We are doing leading only on tofuball's car right now, and I have tested the trailing code on the oscilloscope for both FC and FD type trailing... (the ignition signals are different, FC uses a single IGt signal, and a coil select signal for trailing where FD's just have 2 IGt's, each associated with one of the trailing coils).

13Beast REW will probably be the first to test FD ignition on his car... and I don't think it'll be difficult.

A friend in florida (pmrobert on this forum) is going to be testing FC trailing soon, and I'll be testing it on tofuball's car soon as well. You should read up on the megasquirt threads in the ECU forum to see the details of the testing going on.

Leading only is fully tested on tofuball's FC... FD and FC do pretty much the same thing for leading.

The point is still, as it was before, even if you're not using megasquirt, and you're using haltech or something like that, you can still install and tune yourself if you do the required homework and are very careful.... and I would recommend this to anyone who is willing to learn. Megasquirt is just a better learning experience because of the openness of the project,... (it's open source after all.... the source code is freely available to anyone who is willing to look).

well this was going to be a scathing post about how even some "professional" tuners manage to kill cars, but I will just say this instead.

Tuning is not magic. With enough time and resources spent learning about how to tune a vehicle, everyone can do it. The harm comes when someone chooses to tune their own vehicle without understanding what they are doing (or a shop professes intimate knowledge about tuning a specific vehicle when all they've previously done has been bolt-on ecu's and chip swaps tuned by the ecu/chip manufacturer).

well put, that was the point I was going for... even if I didn't say it exactly that way...

My point was just that why would someone who is obviously inexperienced want to risk that much money just to do something on his own.

Megasquirt may be a real ecu by some definitions, that's fine. Open Source, blah blah blah.
I wouldn't encourage anyone who doesn't have years and years of turbo rotary experience to go out and start trying to tune and learn on the fly. I wouldn't encourage ANYONE to use an open source ECU in their FD. When there are so many other proven ECU's why mess around?

Again, IMO there are somethings better left to people who do this for a living. They have and will always have far more experience and practice. Just wait till one of you pops your motor because you made a small error on a map.