Stussy

I just recently got my s4 tii running on the ms3x. Im having some issues. I followed Aaron cakes guide.
On startup the idle raises to 3000 rpm, and slowly goes down as the temp warms up. After driving for a while, it sits and idles at ~900 rpm.
I have 775cc primaries and 1050 cc secondaries

Now for the questions

1. Does the Req_Fuel value matter for much anything
   1. I used the calculator, 2 injectors, 775cc, 1308 ccs. I get a value of 5.4, The car starts and runs, but then dies about two seconds after. When I change the required fuel value to 9.5, it runs (the rest of this is used with 9.5 required fuel).
2. Is there a value where I set my idle speed, or do i do it with the throttle stop?
   1. I dont have the idle control being utilized right now
   2. after warming up, I can drive and it returns to around 950 rpm.
3. Why am I having the 3000rpm thing
   1. It is also reading lean while its warming up with this issue, ~16afr
   2. I have cold started with the WUE autotune, but had no luck
4. How far should cells be apart (VE wise), just want to make sure im safely going into boost.

Attached is my msq, please look and let me know if you see anything strange.

elturbonitroso

im going to say this again dont use the vr signal conditioners on the ms3x card they dont work good on this CAS get a jbperf board or something similar and the lost sync problems would go way if everything its done right.

Stussy

thatks for the reply, I have a FFE trigger wheel, getting no sync loss

elturbonitroso

are you using the hall or the vr sensor on the FFE kit

Stussy

I have the hall kit

think I found some issues
the required fuel value the calc uses ram well when the engine was warm, so I think it’s dying because the warm up enrichment wasn’t enough, that or something about fuel after cranking.

Malic

I am guessing that you still have the thermowax plunger that does the cold startups attached to the throttle body that water flows though?

With the default TPS, if you calibrate it when warm to be at 0, when cold, the plunger will open the throttle a tiny bit, leading to the high idle. The TPS will display like 16% or something when it is cold.

The stock computer, will lower it when you put it into gear, but the Megasquirt does not do that.

I have a 1987 non-turbo RX7. On mine, I removed the throttle body, and completely removed that cold idle plunger valve and the brackets and arms that it attached to, so my throttle is at 0 at all times, and use the idle air control valve to maintain a high cold idle that tapers down. With it, I can mimic a high RPM start when using higher cranking values, but that is what I have been adjusting the last few mornings so the car does not rev up high and annoy my neighbors, but still cranks on the first try.





Other things I noticed in the tune, your Stoichiometric value is at 13.2, not the default 14.7 for a gas powered car.

I am confused on the use of the MAF, are you not using a MAP sensor to read intake manifold pressure? That stupid flapper door MAF thing on the RX7 is 70-80's tech that can be ditched with a Megasquirt, just need to rewire the fuel pump wires that run though it that detect airflow before it sends power to the pump. MS can handle all of that.

In your timing settings, you have a -10 for fixed timing, the RX-7 requires -5 when setting base timing, not sure if your different sensor ring changes that part, if you still have the default marks to compare, just don't want that base timing to be off by 5 degrees.

I have always been confused about Aaroncakes split timing values on the how to megasquirt website, as he says on the forums here ( https://www.rx7club.com/megasquirt-f.../#post11601929 ) that

I use negative split, and because I am not turbo, it reaches 0 degrees at atmospheric full throttle, which is around 98-100 KpH for a turbo setup.

Your default barometric pressure is 100. I live in MN and for my altitude, 98.4 is default, not sure if that is throwing off fueling calculation if it defaults to 100 every time and expecting that. If you set up tuner studio to show the barometric pressure, you can make sure it is not defaulting to 100 while you are in ND
I used to live in Utah, and barometric pressure there at 7000ft was 88KpH, so I had both of my Megasquirted cars tuned for it. This is the barometric table I run on both cars that I tuned when going up and down in altitude on the way to Vegas, which is closer to 2000ft. , because the idle gas law that MS has is not perfect and I have secondary barometric sensors on my cars that change it on the fly. Single sensor cars will take a reading upon key on, and use that value until the engine is stopped and the MS is restarted again:




I am running 650cc injectors for both primary and secondary, and have a 6.7 required fuel calculation, I've seen that the larger the injector, that number tends to go down, not up. My Turbo Miata is around values of 3.1 with 1000cc injectors , so the value of 5.4 does seem more accurate for your application. That Required fuel number needs to be set for your application and can be throwing off a lot of other calculations because of it.

The injector timing table is 360 across the board for both primary and secondary, they might be firing when the sides ports are blocked by the rotor, so just pooling on the walls instead of atomizing.

Be aware that I am running a 6 port non-turbo car, so my secondary to intake port length might be different then a turbo intake runner, I do not have one in person to see. These numbers are based on the FSM: https://www.rx7club.com/engine-manag...agrams-734262/

This is what I use for primary injector timing, I would think this would be close to the same:

Secondary see note above on nonturbo to turbo difference:



Your ignition table around idle is 18-19 degrees of timing, I have closer to 15, and use timing to control the idle speed, not the idle valve. Not sure if that is making it harder to keep the idle stable.

These are just the things that stand out to me when comparing to my tune.