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909 Posts
Discussion Starter #1 (Edited)
Whats happening supra forums. Long time reader…first time poster… Lets pop this cherry. I wanted to post on my NA-t setup as I potentially did some things that are unique. No, I am not the first one to do any of the below – but I have read a lot of posts and wanted to get this all in one spot for you all. Please ask any questions you want, rip on me and my setup, whatever you see fit 

Engine setup
• 7mge long block rebuilt with 7mgte cast pistons
• ARP studs and felpro gasket
• 7mgte exhaust manifold / ct26
• 3” downpipe / exhaust from all the way back
• 2.5” hard pipes, large FMIC
• 440 CC 7mgte injectors / new 7mgte pump and filter
• Bosch BOV venting into turbo inlet
• Innova wideband 02
• Base timing moved back 5 degrees

fuel system on Phase 1 of the swap
• Stock computer with flapper AFM tightened down, 440cc injectors
• Megasquirt 1 (v3 board) running only as datalogger
Ok I know you’re all thinking WTF you have a megasquirt and are not using it to run your injectors….read on 
I decided to break in the rebuild with the stock computer, the turbo was bypassed (AFM connected direct to throttle body). This setup actually ran ok once I was able to set the AFM spring to accommodate the much larger injectors. Initial tuning was done with Toyota ecu not seeing an 02 sensor. That way I was able to adjust the AFM spring without the computer trying to compensate / go into closed loop mode. At this point it was actually running ok. When I connected the 02 sensor up it would cruise at 15 or so, and WOT (remember no boost yet) would richen up to 12 ish
It actually ran so well that I decided to run boost on the stock computer / tight AFM / 440cc combo. Here is a log of just that. Now before you think “this guy is nuts”…there are a few factors that pushed me into trying this. first I was stepping into this slowly, pulling to 3.5 / 4k / 4.5 etc, and I had data to see what was going on. Did I mention readily available 100 octane Sunoco race gas too? I wanted to run on boost for the last few months of the summer and didn’t have time to rewire/tune etc. I would be happy with 6psi for a short while…if it was safe (and the wideband / megasquirt allowed me to see just that)
Here is a full pull (street). Added a washer to the wastgate by this point. Phone app and datalog show a 7 second 0-60.

7mge ecu log.jpg

Hmm ….seems too good to be true right, how on earth can the stock 7mge computer run so well. The above log is accelerating from a standing stop. Lets see what happens when we roll into some boost, with partial throttle (aka real world driving going up a hill etc)

7mge lean.jpg

Not good at all. For the rest of the summer I was committed to running 50/50 premium / race….and NEVER boosting unless my foot was on the floorboard!
Fast forward to this spring. Megasquirt is now running my 440 injectors in a fuel only setup. Just beginning to tune. Every bit as complicated and time consuming as I expected (and hoped) – Im into this stuff bigtime as I currently work in the technology industry, and previously made a living turning wrenches in the late 90’s.
But….looking to a few Supra Stand Alone ECU pro’s on here to consult on what I am seeing with my logs now. Basically I am wondering
1. Looking at the data log below, Is my injector pulse width reasonable for 440’s (considering my mods). Seems like I am close to maxing out
2. Is my stock fuel pressure a problem – I have the vac hose disconnected from the regulator. Am I loosing fuel pressure (via increased manifold pressure difference) at boost? I do have the fuel relay setup to always output full voltage to the pump.

7mge megasquirt max duty.jpg

3. Feeling surging / bucking now (absolutely no timing changes from previous non-megasquirt setup, stock 7mge timing bumped back 5 degrees). Is my hella rich issue sticking my injectors open / causing misfire ? the lean spikes match up with the stumbles I feel now
data from recent run

549 Posts
If you're using the MS for fuel, swap the afm for a map sensor. Flapper afms are not very accurate, the MAP sensor will be easier to tune with.

909 Posts
Discussion Starter #4
The 7mge ECU is running timing, flapper AFM is hooked up so it has a somewhat reasonable timing curve.

the megasquirt is using map sensor along with the other usual sensors : tps spliced into stock harness, add on gm coolant temp sensor, gm intake air temp sensor right after intercooler)

totally new to posting on here and not sure my images made it up - they show the logged MAP pressures, fuel ratio, duty cycle etc
my tune is primitive at best, 2 hours into my ve table...when I run closed loop with target o2 tables it not too bad off boost
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