Hey everybody

I just wanted to thank everybody for there help in getting my megasquirt project running. It has been a crazy and emotional ride getting it running but it has been sooo worth it. The car desperately needs a tune but it is so much faster than it was with the stock ecu.

Here's a video of it running




Again thanks to Aaroncake and Matt from diy autotune for the help.


Now, I do have a question. Im not getting any response from the bac valve. Ive tried all the frequency values i could find and still nothing. When i was using the ms1, I totally followed aarons writeup for wiring the engine including the diode between the wires on the valve. Now that im using a MS2 on a 3.57 board, do i need this diode? Could this be why its not working?

Thanks

 

The correct freq is 122 Hz... that'd be "4" in your settings. Use the diode... though you may need to replace the transistor now if you tried operating the BAC without the diode.

 

Thanks.

Ive been following your thread and have tried 3 and 8 and have gotten nothing but ill try 4 tomorrow. I havent tried it without the diode but i didnt see any wiring diagrams using the 3.57 board. Guess its good I asked first.

 

So I came home from work today and tried using "4" for the frequency setting and it still had no response. Next Ill make sure I have voltage at the valve.

I tried to get gas today and a new problem arose. I guess it heard me bragging about it and decided to prove me wrong. I am suddenly loosing sync with the cas. This seems to happen at random times but its happening more and more. I got all the way (2 miles) to the gas station with no problems but forgot to bring the premix. oops. So i drove back home and it happened a few times. Got home and checked the connections and tried it again, this time with the logger on and it confirmed my worst fear.


Screenshot:


I followed all the recommendations for canceling noise problems like using shielded cable and running the cas wires away from the ignition. I guess next I should check to make sure the shielding is grounded.

 

Now Ive really pissed it off. Im not getting any rpm signal anymore. I dont understand how one second i am running just fine and the next something major isnt responding. Guess its a good thing i have this weekend off.

 

I had a pretty crazy "no rpm signal" thread a while back. ..

 

Make sure the shield is only grounded at one end.

CAS connector and wiring in good shape? Is the CAS worn out (slop in the rotors)?

As for the BAC, check to make sure you have 12V at one side with the key on. The 3.57 board already has the high current idle mod but you will need the diode. May have damaged the transistor otherwise so you might have to switch to the idle circuit on the Zeal.

 

Wasnt able to get any work done yesterday due to an unexpected funeral but got a few minutes to work on it today.

I took my jimstim and hooked it to the cas and plugged it into my old ms1. Got a strong rpm signal. So i took the ms1 and plugged it into the harness and didnt get any signal again. Checked the cas connector and im getting continuity through the contacts so i guess that means i have to tear into the harness and see where i f'ed up.

And of course ive already wrapped the harness.

 

So I finally had some free time yesterday to get work done on the car. Started tearing into the harness and found one of the wires to the cas broken where I stripped off the insulation. Oops. Resoldered the connection and she fired right back up.

I also verified Im getting 12v on one side of the bac valve and still getting no response. Just to clarify, I didnt try it without the diode. Was just curious if that was the problem. Iv tried all the frequency settings I could find on these forums.

 

Try setting the idle as an on/off valve and see if you can make the BAC click by changing the high/low idle temp settings. That will verify the driver circuit is working.

As for frequency, I've run them from 75HZ up to 200HZ and they have always worked fine. Tried 60Hz on an FD BAC (same as FC basically) on the MS3-Pro on my Cosmo and seemed to get good lift from the valve (but it was noisy).

 

I was using something over 200Hz on my 7 with MS3. MS3 has hardware PWM outputs which means you can run the higher frequencies and not suffer any resolution problems with the duty output.

Ken

 

Thanks for all the responses. I've really enjoyed this project. I drove it to work the past few days and it has really transformed the car. Even with the rough tune, its so much more responsive than with the stock ecu.

I tried aarons suggestion of setting it to an on/off valve and couldn't get it to make a sound.

When the valve should've been "on" (the "fast idle temperature" set to 140 with a coolant temp of 60) I got a reading of 600k ohms between the fidle wire and ground. Tomorrow Ill tear into the harness and double check the wiring and throw the megasquirt on the stim to make sure its working properly.

 

8 months later....


The car runs pretty good. Much better than she did with the stock ecu and wiring. I just got around to throwing the megasquirt on the stimulator and still cant get the ecu to respond with the fidle output. Im guessing that I got a bad board or something.

I am running a 3.57 board with a Zeal daughterboard. Can I just wire in the pwm bits on the zeal card and effectively bypass the busted onboard circuits?

Another problem I'm having is with the tune. I can spend an entire day driving around and tuning the car, stop for dinner, and when I fire it back up, the tune is off again. Not by much but a good +/- 0.5 afr at idle. Im not sure where to even start with this one.

Thanks guys!

 

Yes, you can just use the FIdle circuit on the Zeal. I believe it's the same as the one on the 3.57 board.

As for your idle, are you leaving enough time for it to stabilize before you compare the AFRs? It may take a little while before conditions are the same the last time it was tuned. Or they may never line up, because for example, the idle was tuned as the car sat stationary and heat soaked.

This is where the corrections come into play. You'll likely need to adjust the air temp correction.

Is the idle speed or MAP value changing? If the idle was tuned with the fans on, then once the engine has cooled they are off, you may be running in a different VE bin. Without a working idle valve, this can certainly be the case.

 

Yeah, the idle speed changes by about 200 rpm depending on load from headlights and blower motor. It very well could be that I'm paranoid and worried about the smallest changes. I have messed with the correction table but not too sure how much to add or take away. I'll start paying more attention to the Mat readings and going from there.

It seems like it would be best to focus on that when i get the idle valve straightened out. I can't seem to access the megamanual site right now to get the schematics for the 3.57 board but as soon as I get them, I'll crack it open and get that all working.


Thanks Aaron!

 

The idle variation under load is definitely normal without an idle valve. You can compensate a little for it by running the idle slightly higher, slightly richer, and creating a little timing ledge "below" the idle so that if it begins to fall, the engine will catch itself. But these things are no substitute for an idle valve and all of its wonderfulness.