can't get over 7 psi boost pressure! Someone enlighten the newbe
 

Maybe it is because i am new to all of this but i can not seem to get over 7 psi of boost. Even with the boost computer on i'm only getting about 10 psi. To me this seems a little on the low side, could someone please enlighten this newby on what the problem could be!!!

I hit seven on average, and I have the same mods as you and an 87. I put a race pipe on and on cold days I will hit 10 no prob. That is all our little turbos are good for unassisted. With the boost controller should be able to go to about 12 though. I would suggest an upgrade.

Without an FCD or an ECU upgrade you shouldn't be hitting anything over 5.6 psi (don't quote me on that) for an '87 TII. The '89-'91 TII's are higher. The ECU is programmed to cut fuel to the rear rotor and it'll feel like you hit a brick wall. An FCD fools the ECU into thinking it is running lower boost than you really are and will not cut fuel. This may lean out your fuel mixture and blow your motor. There have been many blown motors with people using an FCD and no fuel modifications. I am one of them. Mine is for sale if you want to go this route. An ECU upgrade (GForce, Superchips, Autothority) would be a better choice. And before I go any further its not the best (ok all you stand alone freaks! :p ). The ECU Upgrade will eliminate fuel cut and depending on your chip and model will remap your fuel curve, timing, etc. I use a GForce ECU with 720 cc injectors in the secondaries, a rewired FD pump and a S-AFC. I suggest you stay on this board and read the 2nd gen FAQ located @ http://www.teamfc3s.org

Hope that helps.

yo, darkside. when you get a gforce ecu. do they already have a program setup for us fc's? or is it all diff for everyone that buys one? and how much was it?

im planning on doing the same 720cc's and a walbro, along with the safc.

thanks
brandon:D

hmmm
 

As long as you have the S-AFC you should be ok up to about 10-11 psi with stock injectors and fuel pump right? (If my mixture runs lean at all (eg: goes below stock levels) then I am going to throw on the 720cc's, but isn't the S-AFC sufficient for that? (as well as a pump?) If the AFC cannot handle that and cannot adjust the fuel curve, then it serves no real purpose...from what I can tell anyways...:rolleyes:

Yes, you can run that combo. I don't know how safe it is but at the very least rewire your fuel pump. There's a site with the procedures somewhere. Someone reading this might be able to point you to it. If not I'll find it for you. Testing has shown a decrease in voltage to the fuel pump with something as little as stepping on the brakes.

You'll see it time and time again that it is easier to tune your car with the S-AFC with larger injectors (secondaries) than with the stock injectors. You don't want to risk locking up your stock injectors. New motor vs. new larger injectors. You do the math.

-Ed

its here:

http://2ndgenrx7.freeservers.com/

under tech info and then you'll find it there.

I had thought I read somewhere that 8.7 psi was fuel cut off on the 87-88 T2's....Can anyone state one way or the other for sure?
Thanks.

Here's what I found:

'87-'88 6.2 psi
'89-'91 8.6 psi

This was off of the teamfc3s.org FAQ.

-Ed

6.2 max 0n 87 TII
 

I have an 87 TII and have not hit fuel cut in it. My car isnt stock and is hitting 7-7.5psi of boost.The fuel cut has to be over 7

fuel cut
 

87-88 i believe its in the neighborhood of 8.7 psi<--------that sucks...89 and up are 10 psi i think, much better

DHRP i think what you stated is max boost in stock condition....you know those 2 choking and killing your rotary cats...

You may need to open up your exhaust system a bit. You need to get rid of the pre-cat and also go with at least a high flow cat. I have similar mods to you and I run 10psi on my car. It won't HOLD 10psi in the summer, but you will see it there most of the time. And in the winter you should see some serious boost, should hold 10psi with ease.

Good luck,

yae i just noticed that too, you never listed an exhaust. get a n1 single and a highflow cat, and a dp and you will get more than you ask for. also maybe too much watch out

what!!!!!!!!!!!
 

OK lets make this real simple--without having to spend all your hard earned money on fuel injectors and boost controllers and on and on,Eld performance in crofton may not know everything about rx7s but they are very good at turbos,i have a 87 t2 took it in to let brian play with it.He put a fuel diffuser switch on it,took the cats off --replaced with one high flow cat took all the exhaust off and replaced it with 2 1/2 stainless steel to 2 bosani mufflers.the car already had a msd ignition system on it before they touched it.for only 300.00--the car makes 11.5 pounds of boost with no lag ---ever---so what im saying is --if you have fuel cut probs ,dont change the ecu--fuel cut diffuser--- and your set-

Re: what!!!!!!!!!!!
 

i couldnt have said it any better;)

Killer_Ride,

Let me explain something here, before you go off and blow an engine. With the stock ECU, you cannot make more than 8.6 or 8.7 psi boost without fuel cut kicking in. What many people do to overcome this is install a fuel cut defenser (I believe that is the "diffuser" that loudazzrx7 is referring to). It is the only way to overcome this if you continue to use only the stock ECU. That said, let me explain how one of these gizmos work.

The ECU decides how much fuel to inject into the engine under boost mainly by two inputs: pressure and RPM. Other inputs will cause minor adjustments, but we won't get into that here. What this gizmo is going to do is intercept the actual pressure (boost) signal from the pressure sensor when it goes over 8 psi and substitute 8 psi for it. Now, let us say, for example, that you are at 11.5 psi of boost at 6000 rpm. The ECU receives its 2 inputs - pressure 8 psi, rpm 6000. It will set the amount of fuel it injects to the proper amount for 8 psi and 6000 rpm. Since the actual condition is 11.5 psi of boost, YOU WILL RUN LEAN - and it is only a matter of time before detonation will shatter a seal - blown engine. Note, this discussion assumes 87-88, substitute 10 psi for 89-91 (it will still run lean, but not as bad). The only situation where an FCD can be used imho is one in which additional fuel provisions have been made (Adding an Apexi AFC for example) for this area where the ECU will not inject the correct amount of fuel. Please, don't do this so you can enjoy your TII for a long time.

loudazzrx7, I know you have confidence in your shop, but please, rethink what you are doing! I hope I do not read about your blown engine in a future post.

Take care all,

Irv, Keith's dad

Couldn't agree more. He will definitely need more fuel to ensure he doesn't grenade his motor. I guess I assumed that he knew that... but I still think his boost problem is his restrictive exhaust system.

Re: hmmm
 

Is the S-AFC sufficient for running stock injectors? Yes it should be fine for 10psi, however you will be running close to max duty on them, and injetor lock may be not far off. Your best bet is bigger injectors, a higher flowing pump, and a S-AFC to tune it all. Bigger injectors with a higher flowing pump, but no S-AFC will let your run richer butmajorly inefficient. Do it right the first time get all three. Now with that said I'm running 9psi on stock injectors and pump and no S-AFC, but it's all comming this winter:D

I plan on getting

a S-AFC
then 720 secs
then exhaust and TID

In that order...Just to play it safe. My only question to those that have AFC's, does the Apexi S-AFC require a FCD or does it take care of that function. I'd hate to spend 320 on the whole shizbang and need a FCD too.

iagree
 

your right,i do not want to blow the thing,and your also correct on possible damage,its not a street car and is only taken to the track .I have yet to grenade it ---but when it does happen---i will be making a trip to crazy rays junk yard ,taking one out of there place f0r 100.00 ---yep a 100 dollars--you take it out yourself the only prob is they only get 1 or 2 in every couple of months

The problem now is, a junkyard motor will be bad as well. The best advice is to take care of your good running motor now, while its still good!

No, the S-AFC does not remove fuel cut. So you'll need to get an FCD or reprogrammed ECU.

-Ed

That is correct S-AFC does not have a fuel cut function so an FCD or reprogramed ECU is neccessary.