Eagle7

I got my '86 FC running with the V3 board over the weekend. Everything connected to MS is stock - except I started with the MS MAP sensor. I'll be switching to the RX-7 boost sensor when I get a little farther in tuning.

It took me quite a while to get it so it would run more then a couple seconds. Issues were timing and mixture (duh!). I had to restab the CAS to get the Megatune advance gauge to agree with the timing light. I'll post a picture later of how it's set.

I had to give it a lot more fuel than I expected - 18 ms crank pulse and REQ_FUEL of 13 with the VE table I copied from some posting on this forum. My engine has the 6-port sleeves removed and a full-out racing exhaust - don't know if that would contribute or not. I'm using a Tech-Edge wideband O2, and it likes to run at about 13.5 AFR. Haven't driven it yet, and probably won't until spring.

My idle is about 700 RPM, and my tach drops out periodically (because the trailing spark is dropping out). The lowest idle I could get with the stock ECU was about 900 RPM.

Now the fun begins. Lots of tuning to do, and lots to learn in the process.

Muy, thanks very much for your help with this. I know I could not have done it without you.

custom13B

Well congrats! My MS equipped 7 is doing the same thing yours did. It will occasionally run a few secends and thats it. Im suspecting timing issues and fuel. What size injectors are you using? Im using 4-720cc on a turbo 13B so no one can help me..yet. Im looking forward to reading what you had to do with your CAS. I installed mine by lining up the yellow tining mark on the pulley and indicator. Then lining up the CAS gear and the mark on the CAS body. I set my trigger angle to 60. I recalculated my req fuel with the 720cc injectors and it came up to 6.4 down from 9 if it had stock injectors. Ive changed my cranking pulse width a few times and have it set to 9 currently. Im thinking about changing to your numbers and just dumping a ton of fuel into it just to get it running then drop them back slowly. Any tips would be great. Thanks in advance,Shawn

Eagle7

I've still got lots of questions, so this may be bad advice, but here's what I did for timing. I started with your approach, and I was way off. You've got to have a timing light. If you don't have one, you shouldn't be installing a MS, so go buy one. Set the "Fixed Angle" on the "Spark Settings" menu to -5, which fixes the spark advance at 5 ATDC. Crank the engine and watch the timing. Rotate the CAS until the timing light indicates 5 ATDC (yellow mark?) - restab the CAS if necessary. Then set the "Fixed Angle" back to -10, which makes it use your spark map. There's probably a better way to do this from within MegaTune, but I didn't try to figure that out.

My injectors are stock '88 NA - I think that's 460.

I was trying small adjustments to fuel without much success. My engine would occasionally backfire out the tailpipe, which I eventually figured out was lean, so I tried a lot more fuel in the cranking pulse widths, the afterstart enrichment, and the warmup enrichment. I misspoke previouly, my cranking pulse widths are now 22 ms and my Required Fuel is at 12.0. I'll be lowering that and raising the VE table settings as I proceed.

My wideband O2 wasn't much help, because when I crank the engine it wants to reboot, and the engine would die before the O2 gauge came back online. Once I got it to keep running the O2 gauge is invaluable.

custom13B

Guess what..I got it running tonight! My wideband (innovative LC-1) does the exact same thing. Yea your injectors are 460cc mine are 720 so I need almost half the fuel setting youll be using. I do own a timing light. I have many issues to resolve as well this is just the beginning. Gonna try and get some sleep...difficult I smell like exhaust. Had it running for over a hour idles a bit high at 1,100 but Im not complaining. Ttyl

muythaibxr

This is basically what you're supposed to do. it can be a little easier to do if you do this first though:

Take the cover off of your CAS, and when you stab it, make sure that if you followed my settings in the FAQ, tooth #2 (to the right of the G wheel's reset tab) is lined up with the 24 tooth VR sensor (this should be the stock position). When you stab it, normally the wheel will move over one whole tooth, and I think the factory computer expects that (I'm going to re-figure my settings taking that into account at some point, so I can come up with settings that don't require a CAS restab). So when you stab it, stab it while holding the wheel in place, and after you've stabbed it, make sure tooth #2 is still aligned with the 24 tooth vr sensor. Do all this with the engine on the 5ATDC mark.

Using this method, I've been able to set the timing in a matter of minutes, and get it working perfectly the way I expect.

If your cranking pulse-width is that high, you may want to consider increasing the priming pulse. Thats like adding a scalar to the values in the cranking pulse-width table. Also, I hope that 22 ms is just when the engine's really cold. In order to get the car to run properly with the calculated req_fuel (should be 9.4 with your injectors), there is a way to scale your whole ve table.

open up Your ve table, and in that table go to "Tools->VE Specific->Reset ReqFuel"

Your current req_fuel should be displayed in the first box. Put 9.4 in the second box, and leave the reset req_fuel checkbox checked. Click OK, and the whole table will be scaled. Send to ECU just to make sure it is saved, and go to the constants page and make sure your req_fuel value is changed. If it's not, change it to 9.4. That should get you running with the calculated req_fuel value, and then you'll be ready to tune.

Eagle7

Oh, I think I was off by one tooth.
I'll have to check that out - I thought the priming pulse was just a single shot at turn-on.
40 - 60 degrees.
Cool. I was hoping I didn't have to manually enter everything.

Once again you've demonstrated why we appreciate you so much.

muythaibxr

1 tooth on the wheel is 30 degrees of engine rotation, so that can cause some problems

It is, and it really helps... when I'm trying to tune cranking pulse-widths, I turn the car completely off between tries just to make sure I'm taking the priming pulse into account. I guess it's not quite a scalar since it only squirts that on megasquirt boot, but it does make a fairly large difference.

Yeah, that's way higher than mine at that temperature, I'm at 12-14 ms in that range. but my priming pulse right now is 13 ms... it's not the quickest start-up, but it's still 2-3 seconds on cold-start.

Eagle7

Thought I'd post an update. I got the idle tuned pretty well tonight - better than that car has ever idled for me before.
026i_mod, MT 2.25b717
S4 harness, S5 intake and rotors, 460 cc injectors, 45 PSI fuel pressure.
ReqFuel is 9.4
VE is 42
AFR is about 12.5
Spark is 0 BTDC
MAP is 41