Longhornxtreme

First off a little background...

I just bought my 8 and am loving it... but I'm finding that I need more power (as usual)

I really don't like the emanage solutions as of now... the resolution is too small and the idea of Ford's stock computer's short and long term trims scare me especially in an FI setup.

So the goal is homebrew turbo... Greddy's turbo is just too small... I really don't think I want to hit full boost till 5k RPM or so... tune for power not 60'. I know this thing won't ever truly hook up and it will NEVER see a 'real' dragstrip. My last sports car was a 99z28 that did an 11.4 on the bottle and a 12.5 motor... but the thing couldn't handle for junk... I want to build a true all rounder... something that will put my dad's '03 911 c2 cab to shame. The 8 pretty much already does that except when we're in the straights....

Accessory function is completely necessary. I need my AC, my electronic assist to work, I wouldn't mind the DSC and TCS to work but then again I've driven live rear axle cars before with drag radials in the rain so I think I can handle not having it.

Cooling fan control is easy to hardwire something to regulate it... The key is deciding whether the stock ECU will play ball with a more robust piggyback such as the Megasquirt... I'm aware that the Msquirt can act as a complete standalone system but I'd still like to 'fool' the ECU into thinking it was still running the engine to retain things like port actuation.

Basically I'm aksing do any of ya'll think that Megasquirt would fit into all of this for running fuel, spark, warmup enrichment, etc... functioning as a standalone EXCEPT for port actuation and accessory function.

Ditching the throttle by wire is no problem... in fact I think that's the problem with the inconsistencies in power delivery that i've noticed but that's butt dyno and an issue for another day and another thread.

I like the idea of learning how to use the megasquirt and calculating base maps myself etc... I like the community... I like the price... I like the opensourceness of it as I have the choice of actually tuning under Linux (i know... i know... I'm a comp nerd sometimes) but that linux option will allow me to keep a laptop in the car permanently...

If any of ya'll can think of why this won't work... Why we couldn't rig up some sort of resistor network to fake an engine that really isn't there to the stock ECU...

I'm looking for any potential problems, pitfalls, AND areas that people think could be improved upon...


Thanks in advance...
And lets keep this thread solely focused on a finding out if this super cost effective and super controllable EMS is a viable solution for the renesis...

swoope

iTrader: (5)

im an ulta hardware comp dork. i am learning linux just to hack directivo. as i said i am a hardware dork, paid my way through school street racing in the late 70s.

i will help all i can with your project, but the rx8 box is controlling the whole car. from lights to dsc, not saying it cant be done, but without the help of the ford motor co to get you throught the encription you are way behind the power curve.

got hardware am willing to share.

beers

rotarygod

I have a Megasquirt running my RX-7. Getting it to run good isn't that hard to do. I can tell you haow to set it up where it will start on the very first attempt. The maps will need to be fine tuned though. I have been looking into the Megasquirt/RX-8 problem and am having a hard time finding a way into tricking the stock ecu into thinking it is still controlling the car. This is important as I don't want it to throw a CEL. The goal is to be able to still have an emissions station hook up to OBD-II and have no error codes so it passes inspection. Making the different intake runner actuators work at their respective point's isn't that hard as you have a few outputs on the Megasquirt that can be programmed however you want them. The electronic oil metering system is not able to be controlled at this time by Megasquirt and obviously neither is the drive by wire. The idea at this point is to retrofit a pre-'89 RX-7 mechanical oil metering pump onto the Renesis front cover and have it directly controlled by the position of the throttle plate. Leave the stock pump hooked up to the factory ecu and just tuck it out of the way. A standard throttlebody would be used but the stock electic motor would still have to be hooked up to the ecu and also tucked out of the way. This should be enough to get full control. The big question is will the stock ecu have any problems with it all? Maybe, maybe not. Megasquirt also has the capability to control rotary timing on both leading and trailing. This is brand new. At this time it can only do a fixed timing split such as 5 degrees all across the board or 10 degrees. You get the picture. I personally like to run a fixed split of 10 degrees nonturbo anyways so this is fine with me. With a turbo you might want 15 or so. It all really depends. Megasquirt can only read the 2nd gen or the 3rd gen RX-7 ignition pickups right now. I'm not sure if it would work with the RX-8 yet or not. It shouldn't be too hard to get it too though. That should be about it or at least an idea of what it will take to get it or any other standalone working with the stock ecu.

Longhornxtreme

So I'm going to need to add my own ignition such as an MSD box? As far as the stock oil metering pump... If we can still have the ECU thinking its controlling the car... can't we just have it meter as usual in a NA setup? I don't think it'd be too hard either to build a new metering pump with some sort of software control (independent of Msquirt) to meter out oil dependant on RPM and any other parameter if necessary... do you know if the stock ECU is only RPM dependant or is it dependant on load, temp, etc?

I just picked up a copy of the shop manual on CD and I need to go buy an oscilloscope to start looking at what the ECU needs to see to not throw lights... My gdad is a retired Elect Engineer who would probably have fun helping me rig up an engine simulator for any controls that would throw CEL's in the end....

I realize that I might be wasting my money but I think fairly soon I'm going to try setting up the Msquirt NA just to see if this whole thing is feasible before I start buying up my turbo parts...

RG - in your opinion what would I actually lose by moving away from the throttle by wire to a conventional tbody? Do you have any recommendations on what tbody to use? New or junkyard... either way is just fine...

EDIT: the shop manual shows the duty cycle of so many diff parameters and what they should be showing... Now if for a couple hundred bucks I can make a simulator to fool the ECU on everything I need it to... hmm... this sounds like a fun summer project

brillo

RG's reason for the mechanical metering pump is that since there is some uncertainty over what the ECU would due if it was "unplugged",therefore, to be safe, premixing or a mechancial pump would be safer.

To be honest, If we attempt this, I'm leaning towards replacing the TB with a conventional cable throttle, which takes the Drive By Wire problem out of the picture, mechanical pump based on that conventional TB, and powering the variable intake ports with the MS.

I'd leave the computer attached to power the radio and other since features, but assume as much control over the car as I can. If you have TCS, I'm not sure what to do there.

Richard Paul

iTrader: (5)

Hey Fred, how do you think this would work for my problem. All I want is for it to control two aux nozzles when in boost. Leave the stock ECU to do it's thing all the time. The only problem I see is that the MAF will see the extra air and fuel it up to the point it has maps for then freak out. We need to make the stock system stay with it's own map and ignore all excess airflow.

If there were no limit on the MAF reading airflow then it would just run fine without doing anything. But we know life is not that kind. And for sure Mazda isn't.
How could we find the limit of the factory programed airflow?
Could that map be extended by other then the factory?
Do I need to start looking up all my old buddies from Ford Racing Development?
Nah, I don't thing racing div has anything to doo with the stock type ECU etc.
They use Motec.

rotarygod

Since Megasquirt is map based, it might work very well for your application. The key is going to be whether or not the factory ecu does anything dumb based on added airflow through the maf. Set the car up to run only 2 psi of pressure. Then take it out for a drive to see how the ecu responds. It seems to undo alot of things by trying to keep the a/f ratios inline with any mods. See if it will learn to compensate boost too.

MazdaManiac

iTrader: (3)

This is for any ECU application:

The RX-8 ECU doesn't care if the injectors and/or coils are disconnected. All it cares about are sensor readings.
You can hook up and fuel computer to control the injectors and ignition and all that will matter to the PCM is that it can still see the sensors and A/F.
So, the ONLY hurdle to be cleared is clamping the O2 sensors. That is it.
Don't trouble yourself with the throttle FBW or induction valving. It will all take care of itself.

rotarygod

So Richard could be jsut fine using the stock ecu to run the car when not under boost and then just merely adding fuel as boost increases to hold the a/f correct? That should be simple for him then. If this is the case, what is everyone who is dealing with forced induction's problem?

Longhornxtreme

So Maniac, In the situation of using the Megasquirt to run the entire fuel and spark, There won't be anything to worry about the TBW? How will the MS get TPS from the TBW?

Or even in Richards case, I guess the TBW is the biggest problem for me... I'd hate to lose cruise control but then again I'm most likely just wanting my cake and eating it too...

EDIT: I just reread my post and I've realized I didn't make much sense..

In order to use MS as a standalone, I just need to keep every factory sensor still relaying information to the factory ECU. Then I need to disconnect the factory ECU from the injectors and coils and figure out some sort of voltage clamp system to keep the stock WB o2 sensor (or do I just need to get everything tuned correctly and then clear any CEL's and then the system will be hunky dory... ) I need to find a conventional TB and rig a cable system to the existing gas pedal, but I need to leave the Pedal position sensor and the TBW TPS system hidden but active. I need to rig up the MS MAP sensor... then I need to go through the whole MS tuning procedure. (Somewhere in there rig up a WB02 setup)

Richard Paul

iTrader: (5)

Their problem is they are blowing throgh the MAF.
I still see a problem if there is a lot more air going throgh the MAF. Unless it just can't see it and does nothing to the additional air. I'll take care of that with the othe nozzles. The O2 sensors will not freak out because we will be within reasonable mixtures for open loop.

MazdaManiac

iTrader: (3)

Leave the FBW system in place and tap into the TPS for throttle position on the MS. No need for a throttle cable. Leave the MAF on the intake side of the turbo and put the MAP on a nipple behind the TB.


Draw through the MAF. The MAF is still in range at the current HP levels. My peak MAF voltage is about 4.2v which is .8v below maximum and .3v over typical maximum N/A.

The reasonable mixtures aren't the issue, it is the taget values that will freak out the PCM. You will want 11:1 or slightly more across the high load line, but the PCM will insist on 13:1 or leaner in some ranges regarless of load. If it sees that it might throw a CEL. Might not. I guess I'll know soon enough.

Longhornxtreme

I hope that works... I can't find it again but I read somewhere that there was a problem with tapping the FBW TPS. If that works then that makes this whole thing so much easier...

I think I'm going to order up one of the $140 kits as soon as I get my paycheck this week... Its going to be one of the ones without Ignition control and It will just be going on the bonestock Renesis... I guess I'll need to order up some sort of canscan to check codes etc or I need to think about setting up my own Wbo2... I'd rather use the stock one for now since I won't be tuning any richer than 12:1...

Anyone got any good posts to doing a DIY wbO2 for not that much money?

Does the shop manual give the corresponding voltages to AFR on the stock wbo2?

Longhornxtreme

YES! MS will work with our throttle by wire system... so we'll be able to keep Cruise control etc...

Check out the pic... there is a TPS calibration setting inside the Megatune software...

So RG, we don't have to worry about throttle by wire anymore... yeah the stock ECU will be changing the pedal position vs TB opening ratio per gear... but that's a whole slew of issues that are going to be avoided by not having to mess with a new TB.

Now to sort out all the different o2 sensor options...

rotarygod

I have a Megasquirt on my RX-7. That's why I want to try it on an RX-8. I already have experience with it. That does not control drive by wire. Different throttle position sensors send out different voltage ranges. You merely calibrate the one you have with the ecu that way. When mine is fully closed it reads 8. Fully open on mine is 220. In order to calibrate the MS TPS with the RX-8 TPS, you need to first send it a signal when the throttle is completely closed. Easy to do with ignition on but the engine not running. To get the top count you will need to have the throttle body itself all the way open. I'm not sure if just flooring the gas pedal with the engine off but ignition on will do this. Someone go check.

MS can read a wideband but only if you have a wideband controller. You can not just plug one directly into the MS. At least not yet. That will be available on the future Ultra Megasquirt project. MSII is a daughterboard upgrade to the existing board which gives you basically 90% of what UMS will be. A future option will be in regards to maps. Instead of entering values which work out to how much fuel is getting added, you will be able to enter in a/f ratios for each load and rpm. With a wideband 02 sensor, it will automatically shoot for that number without you having to go figure it all out. That is in the near future and definitely light years ahead of the other guys.

Longhornxtreme

@RG... I'm aware it won't 'drive' the throttle by wire... but the stock ecu will still be there doing that... BUT it will be able to get the TPS (and then calibrate it... that's what my pic was showing... the calribration setting) from the throttle by wire so we can have working accel and decel maps...

Think of the MSquirt as the most glorious of piggybacks and not a standalone...

MazdaManiac

iTrader: (3)

It does. This is how we calibrate the throttle position for the E-Manage as well.

Exactly. This is what I was getting at.

Marietta 8

Or you could really play ball and go with MoTeC. It's kept me rollin since 1994 without a hickup. I think it could be set up piggyback with stock pcm allowing dsc, eps, etc. to run. The 8 need the m800 though and that's gonna leave a mark where your wallet used to be for sure but it's worth every last cent.

Longhornxtreme

why use a motec when a $500 solution (that figure includes WBo2) does the same stuff?

rotarygod

Using a Motec as a piggyback is really no different than using any other ecu for a piggyback.

Marietta 8

Never mind, no point bringing a gun to a knife fight.

MazdaManiac

iTrader: (3)

More like a Swiss Army knife when a machete will do.

Richard Paul

iTrader: (5)

I'm getting a little old for a knife fight so if I could afford it I'd bring a 12 gauge.
Just to be sure I get to go home make it an 8 round pump with 00 buck.

Shadowscales

with a lot of effort and some know how you can fix all the problemss you are encountering. However i don't have that know how :D

but i do have a .50cal BMG an M16 and at least 3 knives for my fights and if they really want to get nasty a 60 ton tank

Longhornxtreme

RG, do you see any problems with Msquirt or the stock ECU not getting along for the fuel system? As far as I understand the Msquirt can only control two stages of injectors while the RX8 has 3 per rotor...

Also do you foresee any problems with the FastIdle type stuff in the Msquirt?

EDIT: Took out the word cyl and replaced with rotor... I know... blasphemy...