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Running Single on Stock Computer

Old Mar 26, 2006 | 02:00 AM
  #1  
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From: Houston Tx
Running Single on Stock Computer

I have been wondering why you can run single on a stock computer if you only run 8-10psi of boost, I am plaining on getting a power fc soon, but all read have the turbo stuff to install on my car.

My setup as of now is,
93 Turing Auto-Manual conversion, Intake,Intercooler,DP,MP,Cat-Back,Non-seq,koyo,fan-mod,ignition-mod,fuel-pump, Running on the stock wastegate spring,running 8psi of boost

So if i install the single turbo and run the same boost then i really dont see what would be the problem.


Another question also, my secondary injectors are stock 850's, well when i had the cleaned they where flowing right at 900, so why can i upgrade them to 1300 on the stock computer also. If they are the same Ohm's the only draw back that i see it when they come online the car may become really rich.
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Old Mar 26, 2006 | 02:10 AM
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with a full exhaust and single turbo I would upgrade to a Pettit ECU at the absolute minimum and stay at 10 psi or less

you cannot run larger injectors on the stock ECU or a chipped ECU
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Old Mar 26, 2006 | 02:10 AM
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no you cant run a single or 1300cc inj on stock ECU, there are a lot of threads on this and I would do a search
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Old Mar 26, 2006 | 04:22 AM
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I just dont understand why you cant run a larger sec injector if the stock computer doesnt no what size it is, just like running 1300cc on a stock Turbo II Computer, same princeable. Right?
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Old Mar 26, 2006 | 09:07 AM
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The FD uses a MAP system. The stock computer is thinking the secondaries are 850cc, if it's opening them at 80%; 80% on 1300 secondaries is dumping in a LOT more fuel then what the ECU is expecting.

The car will be running rich and running like crap (if at all). You also run the risk of dumping so much fuel into the engine that you wash away the lubricating oil in the cumbustion chamber.

As far running just a single turbo on the stock ECU, it has to do with CFM. Unless your single flows the same or similar CFM at 10 PSI like the stock twins, then it's not going to work.
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Old Mar 26, 2006 | 09:22 AM
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Just bad idea..

Just remember that Stock ECU have set MAP from the factory and can not be reprogrammed unless you get it chipped by M2(no longer) or Pettit.

The reason why most people go with PFC is because its tuneable.

With all the mods you listed, you should definitely use upgraded ECU.
PFC is one of the first thing I recommend to other new rotary owners because not only you could tune it, you could also observe whats going on, ie intake temp, boost, water, inj duty, etc. etc..
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Old Mar 26, 2006 | 09:37 AM
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If you are asking these questions you may want to rethink your diy approach and enlist some local support, there are several individuals in the Houston area that can help. I had a guy call me the other day because he wondered why his car ran like sh*t when he put in 1200 secondaries, yes he had a PFC. While trying not to laugh I mentioned that the ECU was setup for 850's and that he was now running so rich once the secondaries come online there was no way the ignition could light off the rich mix(we're talking 20-40% too much fuel!!!!!!!!!!!!). He put in 1200 as the secondary size in the PFC and he thought it ran great. Well, once I got my datalogit on the car I found he was still running so rich the car would pull lazily thru the rpms under full boost, as in richer than a 10:1 AFR. After a bit of tuning to lean it out and making a bunch of other changes it ran like a top and it will get at least another 2-3 mpg. There is simply no comparison between a crisp running turbo rotary setup right with a conservative tune and a pig rich lazy running money pit that can barely pull to redline.
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Old Mar 26, 2006 | 11:43 AM
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From: NC
^^^ great post
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Old Mar 27, 2006 | 12:25 AM
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10psi on stock twins is not the same as 10psi on a t78. The presure (psi) is the same but the flow rate (cfm) is vastly different. The only way you can run a single setup on the stock computer is it the single is rather small, this keep the cfm proportionately the same. If you are going to spend the money to convert to a single setup, save yourself the rebuild cost and upgrade the comp and fule system as well. It cost far less to do that then get a new motor.
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Old Mar 27, 2006 | 12:29 AM
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Re-A knows the dance. Pressure has nothing to do with flow, hence why your engine blows up when you remove the cat and decrese backpressure (increasing flow thru engine @ 10psi and leaning out)
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Old Mar 27, 2006 | 01:35 AM
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From: Tejas
I step away for a year and see nothing has changed. I swear that people buying fd's should be given tests for intelligence and told to begin researching immediately.

for those of you with beautiful sevens...hold on to them...because eventually there will be very very few left.

mahjik..glad to see you still providing the love around here.


j
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Old Mar 27, 2006 | 04:30 AM
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Single turbo + Stock ECU = Kabooooomm !!
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Old Mar 27, 2006 | 05:59 AM
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From: Houston Tx
Ok Lets drop it, I just bought a Power Fc about 15 Hours ago, So now i started to read the manual for it, and dam it is big.



Always can use more reading material


I am a FB,FC Guru but still working on the FD's, I have done alot of mods on Fc's, Have only blown one, A 190,000 mile Turbo 6-Port, But rebuilt it and it is running strong now at 10K on the rebuilt(Running S5 Rotors,s4Iron and Turbo II Housing) running 10psi of boost. Only fuel mod is 550 Pri amd gslse secondarys with a AFC and turbo II Computer.

Next project after or if i ever get my FD the way i want it is, a Monster Bridge port 13B in my FB, No turbo

Last edited by Rx7_Nut13B; Mar 27, 2006 at 06:01 AM.
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