RavenRx7

CAN YOU TAKE A LOOK AT MY MODS AND SEE IF I NEED AN ECU IN THE NEXT FEW MONTHS....I DONT RACE MY CAR THAT MUCH ONLY WHEN A PUNK TA OR Z28 PULLS UP!

1bad7

DEFINATELY!!! with an open exhaust you could spike as high as 16lbs and then kaboom! get an ecu as soon as possible.

Wade

iTrader: (1)

If you keep your max boost below 10psi and nothing is wrong with your car, then you shouldn't need an ECU upgrade. However the only way to be absolutely sure is to put your car on a dyno with a wideband or rent/borrow a wideband and verify your a:f ratio is sufficiently rich, in the 11:1 range or richer.

Wade

RavenRx7

if i buy a boost controller and set it for 12psi. That will stop boost spikes right??? But i still need more fuel and that's were the ecu comes in place right?

Tommy

You'll still get boost creep even with a boost controller wont you? I think you may want to port your wastegate.....that may help.

theman

Just plug in an APEX'i Power FC and you'll be fine, there on sale all over the place. Otherwise to be safe plug the nipple from your wastegate control to the selenoid and run a pleasant 7#s...

legendrx7

iTrader: (12)

I would NEVER run 12psi with a stock ecu and those mods! You are just asking for it. Dangerous.

Also, whenever you type in ALL CAPS, you are yelling. Most people see it as impolite.

1bad7

Also, whenever you type in ALL CAPS, you are yelling. Most people see it as impolite. [/B][/QUOTE]

sorry

legendrx7

iTrader: (12)

1bad7: I was referring to RavenRx7 not yourself. you just said DEFINITELY which should be YELLED in this matter.

RavenRx7: I cannot stress enough that you should upgrade your fuel maps one way or another. With the mods you have listed, at anytime whenever you are at WOT you could just pop your engine. Take it from my dumbass self, I have done it twice.

That is why I have a 3rdengine 3rdgen

rx7eaven

You really should not be running a midpipe without an upgraded ecu. If possible I would put the stock cat back on to be safe till you get an ecu. I would get the apexi, best unit I have found so far for a reasonable price. $1k is a better price than $3-5K for a new engine!

rx7eaven

With a midpipe you will still get creep and spike...just about nothing cures this however porting your wastegate helps a lot.

FastX7

The only reason I'm running a DP and MP on my stock catback is that they were clogged so I had to replace them and I had a MP from a friend already. My turbos are only boosting 7# cause of a broke vacuum line somewhere. My hosetechniques kit got lost too! So, I have to wait even longer to get it fixed.

RavenRx7

Ok thanks guyz, so is it safe to say. The car will be ok till next months when i get paid. Just in the mean time ---do not " run at WOT" .... can i get some input or the ECU u guys chose and why? And what is the procedure ---do you ship it off or do they send a whole new ecu to you...thanks a bunch and no more playing around for me!

rx7eaven

I would go with the apexi, you seem like me! I want to do everything and this ecu lets you do just about that. It will work with stock twins, mods galore, and singles. I wish I had gotten this one. I believe that you get to keep your stock one and they just send you theirs. All that is needed is a tuner around your area and you got it made I got the pettit which is a very nice plug-and-play but it will only handle a certain degree of mods. Furthermore, there is the m2 which I don't recommend b/c you have the different stages and have to send it back all the time for upgrading
Remember, don't race!! and keep the psi under 10 if possible (which I know it is)!
Oh, pricing: apexi-$1100
pettit-$700
m2-$695
Go to www.rotormotorsports.com and told them that Strike sent ya...best price on the apexi power fc that I have found

legendrx7

iTrader: (12)

Yup, you will definitely be ok if you do not race it. Just don't give into temptation, you could really regret it!

My tuned ecu was already in my car when I bought it. If it was not, then by now I would have something more like the APEXi PFC, Haltech, TEC-III, etc. It will cost you about $700 to tune your ecu and you will be without your ecu for close to a week while it is gone to be reprogrammed. The APEXi unit replaces the ecu so there will be no downtime. But, if you go standalone, you will HAVE to get a knowledgeable shop to tune it for you.

good luck

Sleeper

KNow the feeling about boost and stuff I was at 15lbs, 3' intake/exhaust and cracked a seal. Only problem Is im auto and dont know of any ecu stuff for autos'

Wade

iTrader: (1)

RavenRX7,

You can't raise the boost safely with the stock ECU. If your boost level is above 10psi for more than a few seconds, the ECU will induce fuel cut to the rear rotor to let you know something is wrong. Hitting fuel cut repeatedly will cause problems.

I don't know why I keep repeating this, but I'll say it again anyway. An FD that doesn't have anything wrong with it will run sufficiently rich even with some mods, as long as the boost is at 10psi or below. I own a wideband and have tested this on a few cars. Stock cars max out my wideband at 10:1, actual a/f is probably richer. There is PLENTY of room for mods and increased airflow.

People who say that 3 mods and stock ECU are sure to blow the engine don't know what they are talking about, they are just repeating what others have told them. If their own engines blew in this manner then somethine else was wrong. Also, getting a Power FC or other programmable computer isn't such a good idea unless you have a dyno and wideband so you can tune it. If you have a wideband and dyno at your disposal, you can test your a/f ratio and find out for yourself that you don't need an ECU.

Now if you want to raise your boost level, you will need a host of other upgrades to do it safely. But that is not the topic of this thread.

The points others have brought up about boost creep is valid, a lot of cars will have boost creep with an open exhaust. Some do, some don't. If you have true boost creep (caused by too much flow and too small of a wastegate) then there is no boost controller or ECU that will cure the problem. It is a mechanical issue that can only be fixed by enlarging the wastegate or adding a restriction back into the exhaust or intake.

Wade

RavenRx7

Wade,

Thank you so much for the information. I'm all new to this and I take in what ever my fellow peers are saying. I believe what your saying is correct, do to the fact that my car does smell rich at times. The car has a new motor with 8k on it already.
So what your saying is dont buy the apexi PFC and save my money unless I know somebody around here to tune the chip. Instead port the wastegate.
Honestly I dont know what a wideband is, but I sure like to know. I dont have any dyno tools but I know a few shops that do. So is there an aftermarket wastegate I can buy?? I learning here-- help me out please

pweizman

This is interesting Wade. How long to you have to be above 10psi for the stock ECU to introduce fuel cut?

Maybe I am just lucky but my car is pretty much stock, with the exception of a DP, and Cat-back...and I push 11 psi. Granted, it usually doesn't hold 11psi, but it does hit 11, and drop down to about 10.

I am going to be installing Holley Jets instead of my stock pills soon...to hopefully bring the boost back down to 10psi..

Any info would be good.

Thanks,
Patrick

Wade

iTrader: (1)

Check out Derek Vanditmar's RX-7 website, it has a page right out of the manual about this: http://home.istar.ca/~dvandit/ecu.htm

As you can see, more than 10psi is allowed around 4500 RPM. Also, there is a time factor involved - boost must be in the overboost fuel cut zone somewhere around 2-3 seconds before the ECU will fuel cut.

Wade

Wade

iTrader: (1)

No problem. Maybe I should add more about basic tuning to my webpage so I can just direct people to it, saves typing.

Giving that you are learning, I definitely wouldn't recommend using a Power FC or another programmable ECU unless you have access to a specific tuner you trust who can set your car up properly for you. Otherwise you'd better just keep your boost down or go with a reprogrammed ECU (fortunately, these are dirt cheap used nowadays).

A wideband lambda is a precision device that measures the air:fuel ratio in exhaust gas. Using one is really the only way to verify your car has the correct amount of fuel supplied to it while boosting. People who tune programmable ECU's rely on them. People who have bought bolt-on parts and want to make sure their car is running properly also use them. Some people with stock cars will even use them, since a failure of an injector, fuel pump, fuel pressure regulator or another component can make your car run lean when boosting. Running too lean when boosting will shorten engine life, sometimes *dramatically*.

Usually dyno shops will have a wideband, some shops will rent them out, and nowadays a lot of individuals own them, too. Most widebands can have a probe inserted into the tailpipe or the sensor can be put in the stock O2 sensor location.

Hope this helps,
Wade

pweizman

Thanks for the info...

I am a bit confused reading the diagram though.

It looks to me like below 111 KPa you are fine....however 111 KPa is ~16 Psi...

Maybe I am missing how the throttle position plays a role in it...

Am I miss reading the diagram or what?

Patrick

KevinK2

so the top line for fuel cut starts (at left) at 54 in hg. subtract 30 (14.7 psi) for ambient, and that's 24 in hg on gage at sea level. Same as 11.8 psi.

another link for table:

http://www.scuderiaciriani.com/rx7/fuel_cut_info.html

wade's right about stock oem is set rich. but, if the mods include mid pipe, or big IC in cool weather, good to at least check with std o2 meter in cabin. should stay above .9V at wot.

usually need to open the wg pill with mods, to avoid fuel cut. this also covered in the link.

Tommy

I'm running a dp, catback and intake on the stock ecu. my car runs rich at idle and also still pretty rich at WOT. My friends say they can smell it running fairly rich when i'm on the throttle. I'm getting a fuel cut though but only in fifth gear. No reason to chance it though......i should upgrade my ecu soon.

eurautodave

i'm also running dp, cb and open airbox. i just put my car together this fall so when i added my boost guage i was surprised to learn my boost spiked at times near 15 psi. usually it settles quickly back to 10 but sometimes 12 or 8. i put all new silicone on the engine but this car used to be an auto and i don't know what kind of crazyness i built into it. i'm thinking about the pfc just to help trouble shoot. any ideas?