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How to tweak the stock computer?

Old 04-26-06, 08:11 PM
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How to tweak the stock computer?

Hey guys, i've got an 87' N/A that i'm running in SCCA ITS class. I have to keep the stock computer box Housing but i can do anything to the computer itself inside as long as it can be concealed inside the housing w/o modifications.


So my question is, are there any computers out there or tuning programs that can either go inside the computer housing or can tune the computer but not stay connected to it? or places i can send my PCM to for it to get worked on? My car outhandles most of the competition in my class but i lose a bunch of speed down the straights.

Oh and piggybacks wont work because that's not legal in the class. I know some of the top guys run a computer called Motec because it actually fits inside of the housing, but i'd like to try and see what yall's take on that computer is or if there is something that is better out there.

Hope that wasn't confusing, thanks for any help!
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Old 04-26-06, 08:27 PM
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Megasquirt is your friend. Have a look around at the megasquirt section, there's a few people who've installed them in the stock case, and even one guy did it to his ITS car. Be prepared to do it all yourself though, it's totally DIY, but it's fairly well developped and there's lots of information and knowledge.
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Old 04-27-06, 07:13 PM
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iirc microtech's also fit inside the stock case. therse a thread around here somewhere of a guy taking a pic of there setup
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Old 04-27-06, 07:15 PM
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I know a guy that runs ITS with a Motec inside the stock computer box.
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Old 05-01-06, 11:24 AM
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thanks for the responses guys, i'll be sure to look into that stuff.
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Old 05-01-06, 03:38 PM
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You could talk to our friends at SpeedSource. They have done several MoTec conversions. Some of the aftermarket boxes require running a vacuum line into the new computer--not legal. Others eliminate the Mass Air Sensor-also not legal. Don't forget that you are not allowed to modify the harness either.

Jim
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Old 05-01-06, 04:37 PM
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Although the MegaSquirt in standard form takes a vacuum line, it is easily modified to use the stock MAP sensor. (one of the benefits of a completely open source design)

Unfortunately the first round MegaSquirt plug n play group buy is already filled.
https://www.rx7club.com/showthread.p...95#post5574295

You could wait for the second round or build your own by copying their design. They have already figured out all the hardware and software changes to make it completely compatible with the stock ECU box and wiring harness. (plus one modification to read the stock MAP)

ed
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Old 05-01-06, 08:28 PM
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I don't think the plug-n-play MegaSquirt will work for you, because I don't think it will fit inside the stock ECU box. They're building a MS box and providing an adapter cable to attach to the stock harness. If you want to go MS I think you'll have to build a custom configuration. There's a couple of examples in the ECU forum of people that have done that.
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Old 05-02-06, 12:16 PM
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we ran an e6x haltech in the stock case, worked great. we ran it in NASA so the harness is open, and no afm was ok.
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Old 05-02-06, 12:25 PM
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Originally Posted by its66
You could talk to our friends at SpeedSource. They have done several MoTec conversions. Some of the aftermarket boxes require running a vacuum line into the new computer--not legal. Others eliminate the Mass Air Sensor-also not legal. Don't forget that you are not allowed to modify the harness either.

Jim
Hey Jim,

By "emliminate" do you mean "ignore" or "replace with MAP"? I know the GCR says that you cannot add sensors, but I didn't think that there was any problem with ignoring inputs from existing sensors.

-bill
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Old 05-02-06, 12:37 PM
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Originally Posted by Xenogenesis402
My car outhandles most of the competition in my class but i lose a bunch of speed down the straights.
Someone else running ITS may want to chime in here, but I woudn't expect the competition to pull that easily on you on the straights, even with the aftermarket CPU. Especially if your corner exit speeds are good.

(ummm, are you talking about other ITS 7's as competition, or are you looking at the BMW's?)

I assume that you have an S5 engine - are you running the .48 or the .512 rear end?

Have you been up on the dyno recently? What are your numbers?

How old is the engine? For what you would pay for a Motec solution, a fresh engine may be a cheaper alternative.

-bill
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Old 05-02-06, 02:55 PM
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Originally Posted by wrankin
Someone else running ITS may want to chime in here, but I woudn't expect the competition to pull that easily on you on the straights, even with the aftermarket CPU. Especially if your corner exit speeds are good.


-bill

Good point. Speedsource had been quoted on other sites as saying their Motec is worth 5-10hp across the rev range versus a stock ECU. There are also some gray areas that open up easily for power production when the Motec is used that I won't go into. Having not used their ECU and knowing where my car stands in terms of tune and power output I would guess that these gray areas are responsible for a good deal of that power and I'm guessing 10hp is optimistic.

Having said that, in our experience "tune" is largely responsible for the power difference between a front running car and a mid pack car. Meaning Speedsource could send you an engine and if you install it with stock electronics and don't attempt any kind of optimization you'll be down on power to someone with a stock shortblock that's spent time on the dyno and knows what to make of that time.
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Old 05-03-06, 11:00 AM
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Bill,
I worded that poorly. MY interpretation would be that as long as you use the stock, unmodified wiring harness, and the stock, unmodified ECU case, what ever happened to the signal inside the case would be legal. I was thinking that someone might feel it legal to removed the MAS since their aftermarket system didn't require it.

Bill is right on his assumption that the other ITS 7's are probably not pulling you that hard just because of ECU. What do you have for Exhaust? That is the single biggest gain. S5 rotors, housings and intake? 5.12 diff. 225/45 tires? Shocks? The motec equiped cars I hav run against(mine is not) are faster. But only a portion of that speed is from the motec. I've been better by better drivers in lesser cars also.

Dyno?? Dyno plots with A/F readings will help determine if there is an actual problem with the car/tuning, or show where there is some opoortunity.

Jim
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Old 05-09-06, 02:27 AM
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Originally Posted by its66
Bill,
I worded that poorly. MY interpretation would be that as long as you use the stock, unmodified wiring harness, and the stock, unmodified ECU case, what ever happened to the signal inside the case would be legal. I was thinking that someone might feel it legal to removed the MAS since their aftermarket system didn't require it.

Yep stock ECU box, with the aftermarket computer hooked to the FACTORY harness you are golden.
You can also add resistors etc to the existing stock ECU or aftermarket to make things work.

There are a LOT of people out there with aftermarket ECUs in their FI cars. We with RX-7s are lucky.. we have a large box that we can get silly with the internals of.

I know you get a lot of performance from a aftermarket ECU. Pick one.
Tuned a friends 88 AUTOMATIC!!!!! With a Wolf 3D 3.0.. and it would bark the tires nicely into 3rd. (Yes an auto)
You can get a lot more performance with nearly any aftermarket ECU.

Remember.. The factory ECU has to make the car drivable for your grandmother.. and zippy enough for you to enjoy it... while still getting good mileage, and low emissions.
Re-tune it for max power to the wheels on a dyno, and you will be surprised.
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Old 05-09-06, 08:54 PM
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going from an s5 ecu to the haltech gained us a bunch of power in the off peak areas, also it let us rev it higher. this did get us off the corners a bunch faster.
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