Here is an excellent thread explaining the IAT2: https://www.svtperformance.com/threads/lets-talk-iat2.1017427/page-2
Post # 36, SKUD does a great job explaining everything.
Post # 36, SKUD does a great job explaining everything.
Self Tuning With SCT Pro Racer
- Thread starter 03cobra#2
- Start date
That's such great info. I wonder it's ok delaying the retard to start at like 130 as opposed to 100....and keep the -60 value at 150.
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I have heard of people delaying the retard and then making the adjustments on the tables but that's something I haven't tried. e85 might give you more room to play with since it's more knock resistant.
Did a little more datalog going and I'm trying to wrap my head around these spark tables. I hear people say that the ecu will choose the lower of the 2 tables between borderline knock and mbt.
It was a little cooler out today so I did a couple wot pulls. With Iat2's at 110 I saw 20* of timing at 6300 rpm. Which sounds about right. In my borderline knock and mbt table it's set for 19* @ 5000 rpm and 21* at 6500 rpm max load row. I'm pretty satisfied with what my spark is doing at wot.
Now where i get confused is what spark table is the ecu pulling from and what is acceptable spark advance for E85 at part throttle / medium acceleration. When I datalog spark source during acceleration I'm at spark source 2 mostly and sometimes spark source 1 for a brief time here and there. I'm thinking spark source 1 is the mbt table and spark source 2 is the borderline knock table? If anyone has some clarification on how this works that would be great.
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It was a little cooler out today so I did a couple wot pulls. With Iat2's at 110 I saw 20* of timing at 6300 rpm. Which sounds about right. In my borderline knock and mbt table it's set for 19* @ 5000 rpm and 21* at 6500 rpm max load row. I'm pretty satisfied with what my spark is doing at wot.
Now where i get confused is what spark table is the ecu pulling from and what is acceptable spark advance for E85 at part throttle / medium acceleration. When I datalog spark source during acceleration I'm at spark source 2 mostly and sometimes spark source 1 for a brief time here and there. I'm thinking spark source 1 is the mbt table and spark source 2 is the borderline knock table? If anyone has some clarification on how this works that would be great.
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Found this in another thread I have saved on my computer that has my SCT stuff.
Fuel Source:
0 - Closed Loop
1 - Startup Open Loop
2 - Base Fuel Open Loop
Spark Source:
0 - Cranking
1 - Max Allowed/MBT
2 - Borderline Knock
3 - Torque Control
6 - Low Load
7 - Cold/Low Load
8 - Idle Control Sitting on Min
9 - Idle Control in Control
FWIW I've always made the spark tables match. No guessing that way. For 91 I think I increased my part throttle spark 3 or 4 degrees from SCT's base 91 settings. Made the throttle response really good. I imagine E85 can go way more than that. Maybe try 5 or 6 degrees from base?
Fuel Source:
0 - Closed Loop
1 - Startup Open Loop
2 - Base Fuel Open Loop
Spark Source:
0 - Cranking
1 - Max Allowed/MBT
2 - Borderline Knock
3 - Torque Control
6 - Low Load
7 - Cold/Low Load
8 - Idle Control Sitting on Min
9 - Idle Control in Control
FWIW I've always made the spark tables match. No guessing that way. For 91 I think I increased my part throttle spark 3 or 4 degrees from SCT's base 91 settings. Made the throttle response really good. I imagine E85 can go way more than that. Maybe try 5 or 6 degrees from base?
Thank you for posting that. I think what I need to do is compare my spark table to a stock cobra, take a look at the sct race gas value file, and see where I'm at.
Most of my normal driving seems to be in the mid 20's to mid 30's.
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For E85 and 8.5/1 compression....20 degrees is conservative timing. You can easily dial in a couple more than that. As far as IAT2, no need to retard any timing before 150. Zero. Maybe even further.
Thank you. So should I start the act retard at say 150? Then have it pull 4-5 degrees by the time it reaches 160-170? Right now my spark tables max out at 21.
Edit: these spark tables are the last part of my tune I have not really touched.
I think that's a reasonable setup to start off. Probably erring on the side of caution, but a bit looser than retarding at 100 or even 130. That was way too conservative. The benefit of ethanol is occurring well down below the IAT2 sensor, so it's a different ball game regarding e85 timing retard vs pump gas.
Now the pump gas tune? Absolutely start retarding at 100. 150 game over, cut it off at the knees.
Cool. I'll adjust my tune. Appreciate the insight.
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FWIW, my short time of research showed some tuners not pulling tuning until 175°. Not sure I'd ever run that high myself.
For my pump gas tune I have it pulling timing at 130. But it pulls it pretty drastically. Basically by 150 there's no power left. And I'm still on conservative timing.
For my pump gas tune I have it pulling timing at 130. But it pulls it pretty drastically. Basically by 150 there's no power left. And I'm still on conservative timing.
Thanks for sharing. I changed to start pulling at 150 and have -80 set at 175, then -100 at 200. That should allow me to hit max timing and still be safe.
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Just curious, how much timing do you have set to pull by 150*?
It's 6 or 8 degrees. I'd have to double check. But I'm also only running 14 degrees to begin with.
Nice. The other factor to probably err safe is the aftermarket cams. I'm not sure if the grind you have create higher cylinder temps or not versus factory cams. Something to consider. You can always push the timing retard further out as you see more data over time.
They are off the shelf. Increased cylinder temps are a possibility I suppose. The car runs really well and seems that any adjustments I make to dial in the car in really is just to satisfy my ocd when looking at my logs lol. So this fall when we have cooler weather I'll head back to the dyno and throw ice in the intercooler tank. Then I can play with max timing a bit and see what my hp number is.
Back a few weeks ago I made just a bit over 700 on a mustang dyno with timing maxing out at only 17* because of the heat. Should end up being mid 700's on that mustang dyno when it's all said and done with cooler temps and timing at 21 or so. Overall I'm pretty happy with those numbers.
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For sure. I knew when you said it "only" made 700, the tune was max safe. Timing and retard. If the IAT2s were elevated and the tune at that time had retard coming in sub150 like a pump gas tune......it could have been extremely soft result.
The shop I took it to they tune a lot of cars and get them on / off the dyno as fast as they can and apparently tune on the safe side. That's understandable. They did a good job of getting the tune safe and in the ballpark. But the tune was rough around the edges and have done a lot of tweaking in a lot of areas.
Self tuning sucks and is kind of fun all at once.
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On the flip side of that think of the power you made at "low" timing. I'd say over 700 with that timing is pretty impressive. Even more so if it was hot outside.
Yes, it was 90 plus outside and he said iats were 150 plus the whole session.
Mustang dyno are heart breakers for sure. With my old combo I had 601 & 602 at the wheels on 2 different dyno jets. Put it on a mustang dyno and made 480 at the wheels. I was shocked at the difference.
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