speckamp

As some of you know, I've been toying with the idea of installing a Megasquirt into my 85 GSL-SE. And as most of you that knew about that know, I've done very little about it since I got the MS, almost 7 months ago. Well much to even my suprise, the install is progressing quickly towards the end. As we speak the car is warming up on what is probably it's last time ever with the stock ECU firing the injectors. The megasquirt is about 1/2 wired in and is monitoring a variety of stock sensors as it does warm up. This ECU seems well suited for this car, and there are quite a few people installing them on rotaries. We've got a couple GSL-SE's, a couple NA 2nd gens, and one very intresting 4-port 13B in a lotus 7 clone . Anyway, I think I heard the idle kick down so it's time for me to go cut some more wires and solder stuff. More updates as this progresses. My website is www.ub3rgeek.net, and the install log I'm keeping is at http://www.ub3rgeek.net/~mernisse/RX...tle=MegaSquirt

wish me luck
matt

Bruceman

iTrader: (5)

Excellent!!
Keep us up to date and post pics

David88vert

Mine is half wired in. It's all assembled. making fine changes to it now.

David88vert

Where did you take your MAP vacuum from? Pic?

I haven't done the Wing Diode mod and the Zener flyback mod, do I have to do it for certain? Any more info?

One of the guys sent me a .s19 file that should allow the stock temp senders to work. Did you try that file first?

speckamp

David, no, you probably don't have to run the flyback mod, since you're running 4x480cc/min injectors. The GSL-SE's run 2x 680 or 720 depending on year, which means my idle pulsewidth is going to be REALLY short, so I figured it'd be a good idea to just start off w/ the flyback mod and not even have to worry about the idle problems later. (I hope)

I took the MAP line off the old dizzy advance line. I had eliminated the vac advance a while ago, as well as the vac control for the BAC valve (the solenoid that controlled the vac signal to the BAC was DEAD, this solved a hunting idle problem) so I tee'd into that line to put my vac gauge on in the cabin. This is the same line I took the MAP signal from. I'll try and get a digi cam later to snap pics with.

I only cut 2 wires (well 3, but I only needed to cut 2 in retrospect), INJ10 and INJ20, the MS is hooked into the stock ECU harness w/ a 12 pin molex. The 2 wires I cut go into an indentical molex of the opposite gender, so I can just pull the carpet back and swap between stock and MS ECU. This is prolly a moot point since I don't think I'll really ever switch back. (originally I was going to leave myself the option so I could continue to have a functional car that I could drive normally while tuning, but it's almost winter and I've got my winter car up and running finally so it's not really nessicary.

I didn't try the CTS or MAT sensors, since I think the 2nd gen ones are different from the 1st. If you wanna take a look for me, see if you've got 2 wires going to the CTS and MAT sensors on your car. If so see if one's +5v and the other's ~1-2v , if so I'll try and flash the new .inc files into the MS and see if that works. I just don't want to dump + voltage into a line on the MS that's expecting a sink to ground.

slowly but surely
--matt

David88vert

Actually, I have several 7's. Mine is going in a GSL-SE as well, not my convertible.

renns

Hey guys, good to hear there's some MS progress! I've got mine pretty well sorted out now in my n/a '86. I was running the beta dual table code, but discovered some glitches, so I'm back on the standard code running primaries only. I can still run WOT to nearly 6k before hitting 80% duty cycle. Seems Mazda runs their injectors pretty conservatively from that standpoint. Once I've got the car stable, I'll back up my settings, and work further on the dual table side. I'm seeing a decent idle without the flyback mods. Pulsewidth about 1.4-1.5 ms at warm idle.

I'd recommend sticking with the stock sensors (gsl-se coolant and mat sensors are same as early 2nd gen) if at all possible. I wrote a program (EasyTherm), that allows the user to key in temp/resistance pairs for the stock sensor (data from manual or test), and it generates new include files, and will also update the .s19 and download to the MS. Grab a copy from the files section of the Yahoo site. It'll save you loads of grief.

I've also got the Palm interface running now, and am mounting a hacked cradle semi-permanently in the car so I can datalog and /or tweak settingsany time.

I'm letting the stock ECU run the ignition and IAC, so I get the stock fast idle operation. Seems to work just fine. At this point I am pulling air through the MAF, so it's switch is still controlling the fuel pump. That'll go eventually, but given that this car is test mule only, I'll likely leave it as-is for the winter. One area to take a look at is TPS. You'll likely want a full-range unit. I adapted a spare I had laying about (GM, I think).

speckamp

Lucky

Anyway, the schematics I've got for what someone posted as an "85-88" lists things that the GSL-SE cpu doesn't have, like 4 injectors I don't have a shop manual for a second gen (I don't own one, therefore... ) so I don't know how the 2nd gen temp senders work.

In your case, since you are putting this in a GSL-SE, you might need the flyback. You might get away without it, I don't know, I havn't gotten the car running quite yet to find the pulsewidths at idle yet.

renns

I've got the FSM for 2nd gen cars and 1984 GSL-SE. The temp-resistance data for the air temp sensor in the intake plenum and the coolant temp sensor by the thermostat are identical.

Go to http://www.iluvmyrx7.com/ and download the appropriate FSM for your vehicle so you can verify the above statement for yourself. IMO it's a waste of time to try to adapt incompatible GM sensors unless you have some other reason to do so.

jayroc

cool, i never saw that page before. some good info there.... thx

speckamp

I found the FSM for 88 last night by googling, and couldn't quite tell from the manual, but is one leg of the temp sensors pulled to ground or +5v? on the -SE it's pulled to +5v so the other leg shows ~1-2v, which worries me, like I said, since the MS is expecting the sensor to be pulled to ground not +5v. However if the 2nd gens pull the sensors to +5v as well, then I'll happily use them.

Btw, I followed your install on the yahoo group and that was what finally kicked me in the **** to get mine going.

oh, and idle pulsewidths of 1.4ms? what injector sizes are you running? I'm scared to see what mine would be...

--matt

edit: oh, and I love the palm app. I'm probably going to mount my palm in the car so I can have real time data available.

renns

I was working on the assumption that those sensors were grounded to the engine block like your typical thermistor. I made that assumption, and it seems to be working fine, ie air temps and coolant temps seem realistic (actually, air temp seems to read about 20 degF high right now, but that's not a significant issue presently). Idle pulse width is something like 1.4 to 1.6 ms depending on idle speed. I'm running the stock 460's right now.

I've put together three more palm apps that address 90% of the settings needed, so I should be laptop free by the end of the weekend. I hate the laptop!!!! Battery dies, it slide all over the place, and makes me glow at night like I'm Homer Simpson coming home from work... The good news is that it logs forever. I'm still working out the issues with the Palm to be able to write to the full available free memory.

Where abouts are you located in NY? I'm on the Canadian side, about 1.5 hrs from Buffalo.

If you like I can send you my present maps and constant setting. Contact me at renns_99@yahoo.com, or on the megasquirt list. PM is a redundant feature for me...

speckamp

Hrm, the 2nd gen sensors might be the same part, but it looks like the second gen's ground them which makes them compatible to the MS, wheras the 1st gen's pull 1 side of the sensor to +5v. Put a DVM on the CTS and see if it reads a resistance to ground or if it reads a posative voltage.

The temp sensors on the GSL-SE are 2 pin jobbers, so no, they're not grounded to the block. I don't care about replacing the AIT sensor with a GM part if I have to, I just don't want to replace the CTS sensor, since that means I'll have to get a new coolant gauge, or I'll have to drill and tap a hole in the water pump for the GM sensor. (which I'd rather not have to do)

In other news, I ordered the replacement MOSFETS and Zener diodes, I'll have them late next week, so in the mean time I'll clean up the wiring harness I made and snap some pics. I'll post a howto on my site when I get there.

btw, I'm in Rochester, Ny, ~1.5hrs east of Buffalo. I'll drop ya an e-mail a little later, I'd be intrested in looking at your maps.

--matt

renns

Matt,

You got me thinking with your last post, so I dug out the FSM's.

The sensors in my 86 are 2-pin versions visually and electrically identical to those from my GSL-SE parts car. Rather than simply grounding to the engine block, these sensors ground through the ECU. You see a voltage at the harness connector because the thermistor is connected in series with a bias resistor, which is held at some regulated voltage inside the ECU.

I'm attempting to attach snippets from '86 and '84 FSM's below:

On the '86 schematic note that pin 2C is used as a dedicated signal ground for the sensors. The arrow beside the conductor indicates current flow.

On the '84 schematic the setup is similar, grounding through pin T in your GSL-SE ECU.

In other words, no worries, mate! The sensors work as expected.

Also, if you look closely, I think you'll find TWO coolant temp thermistors on your engine. The one at the thermostat is the ECU input, the one below the oil filter is dedicated to your coolant temperature gauge. No worries here either!

Hope this helps.

renns

Here's the other attachment.

speckamp

outstanding, well I guess that solves my remaining input problems I ordered the mosfets to replace the ones I lost that came with the MS, and they'll be here thursday so I have a little while to tweak the startup values of the MS, and cleanup the wiring in the car a little.

I need to check the datalog I made with your palm app to see what the tpos does at the moment, I know it shows WOT early, but I've noticed that the vac gauge goes to almost 0 inHg vac around 1/2 throttle so I'm not worried, I figure the only thing the tpos is used for is accel enrich and closed loop cutoff, so I'm not worried since I cruise at 1/8-1/4th throttle and the accel shot should be okay as well (i've never "mashed" the gas from over 1/2 throttle anyway ).

But other than waiting on parts I think I'm almost ready to start tuning. Now if only the linux PCC was ready, i'd be golden

Oh yeah, if I replace the .inc files easytherm generates with the ones for the RX-7 (without entering the values into easytherm) can I send them to the MS w/ easytherm?

so close..

matt

renns

I don't know for certain, but my feeling is that the stock TPS will not function well in our application. Take a look at the range of motion, and you can see that the cam comes off the TPS plunger very early in its range of motion. I had a few misc tps's kicking around from other applications, and adapted one. I adapted the stock three-pronged connector to my new TPS, so it fits like stock. I also can revert back if I wish, although that priority is dropping quickly as I fine-tune the MS install.

Regarding ET3: No, it will not send your .inc files, only the ET3-generated ones. Just use the data from the FSM for the sensors, and key it in. It takes 2 minutes or less to update your MS to suit. Be sure to copy the ET3-created .inc files into your MegaTune directory so that MT can convert to proper engineering units for the display.

In case you don't have the FSM data, see attached.

Felix Wankel

If it helps any, the S5 RX-7's have a dual plunger full range TPS. The older ones are all the way open at like 30% throttle.

abeomid

Thanks Felix

speckamp

S5 as in 89-91? At first that looked like an 85 on my monitor

Now the trick is finding one, anyone got one for sale?

--matt

slinges

I'm just curious - what are you guys using to control the spark?

fatboy7

Actually, I've got a S5 TPS from my Jspec 13BT. I'm going haltech, so I'd be willing to sell it. PM me if your interested

Felix Wankel

GSL-SE's have distributors. No ECU intervention. I'd imagine you would just leave it alone.

speckamp

Right now spark is handled by the stock dizzy via an MSD setup to direct fire the leading plugs.

As for the TPS, after alot of thought and some testing here's what I've come up with.

Stock is fine. It rails out at about 40% throttle like Felix said, but the only reason the MS needs it (alot of VW people don't even use it) is for acceleration enrich, flood clear and decel enleanment. It uses MAP values for everything really important. So for right now I'm sticking with stock. Seems fine for me. I've got the car running, but still need to finish a few things before I can take her out an tune her (leaky diff is #1, well... it stopped leaking... so there's probably no fluid left in it.)

--matt

David88vert

So you're using the stock TPS? Hmm, that's the only reason that I haven't finished mine.