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Discussion Starter #1 (Edited)
Do you guys that move from Stock ECUs to AEMs find that for the most part the timing numbers you end up with are similar to the stock ECUs timing numbers?

I know the stock ECU runs 23deg advance if it detects no knock. Ofcourse thats a bit much in the peak torque regions with high boost...

Most cars with stock ECUs run around ~19deg on stock twins and 17psi and pump gas. I can't get away with nearly that much on the AEM. More like 12-14deg on pump gas with that boost.
 

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phorcefed00 said:
Do you guys that move from Stock ECUs to AEMs find that for the most part the timing numbers you end up with are similar to the stock ECUs timing numbers?

I know the stock ECU runs 23deg advance if it detects no knock. Ofcourse thats a bit much in the peak torque regions with high boost...

Most cars with stock ECUs run around ~19deg on stock twins and 17psi and pump gas. I can't get away with nearly that much on the AEM. More like 12-14deg on pump gas with that boost.


Stock computer runs much more timing than I do with the AEM. I like to be safe...... Id rather turn it up one psi, than risk detonation through timing.
 

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Discussion Starter #3
Ditto...I'm pretty used to just giving an engine what it wants in terms of timing..and always end up much lower and still make good power. I was just curious on the discrepency on the numbers of the stock ECU vs AEM. I wonder if they correlate at all?
 

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Sound Performance said:
Stock computer runs much more timing than I do with the AEM. I like to be safe...... Id rather turn it up one psi, than risk detonation through timing.
Larry, did you ever experiment with changing the timing on the stock ECU...it CAN be done through the diag port and an adjustment tool.

Jason
 
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phorcefed00 said:
Do you guys that move from Stock ECUs to AEMs find that for the most part the timing numbers you end up with are similar to the stock ECUs timing numbers?

I know the stock ECU runs 23deg advance if it detects no knock. Ofcourse thats a bit much in the peak torque regions with high boost...

Most cars with stock ECUs run around ~19deg on stock twins and 17psi and pump gas. I can't get away with nearly that much on the AEM. More like 12-14deg on pump gas with that boost.
This is a bogus question. IF you run afr's like the stock ecu, you can run the same timing....but why would you want to?
 

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You CANNOT adjust anything through the DLC on any Supra (JDM or Domestic). Only a few models of Toyota vehicles were reflashable until 01MY and not all systems/software were/are reprogramable. Some ECMs like the Tundra and IS's in the first few years had both 16 and 32 bit processors in the hardware could only be partially changed.

Now changing the MAF input to "tune" the car will affect timing through making the ECM think the engine is under lighter load than it is and therefore the respective timing. Like JS said, at a given A/F regardless of the ECM, the engine will only take so much timing. It doesn't care what ECM is commanding it.
 

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Oh and I also mean a Gforce/technosquare ECM cannot be reflashed through DLC2. Those have a modified motherboard and chip in place of the stock nonreprogrammable chip. The chip has to be done externally. Tadashi is an old friend and has done several spec cals for me so I know all about his stuff.
 

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Are you sure that the timing is corect on your EMS? The AEM EMSs are notorious for not haveing the same timing that it says. This is a sync problem. Check your actual timing with a timing gun. You might be running more timing that you think.
 

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Taffy said:
Are you sure that the timing is corect on your EMS? The AEM EMSs are notorious for not haveing the same timing that it says. This is a sync problem. Check your actual timing with a timing gun. You might be running more timing that you think.
I think this is an excellent suggestion. I recently converted my 2jz-ge from mag-pickup to hall effect to run after market TT cams. To test the stability of the new cam/crank sensors, I set timing to 10 degrees all throughout the vacuum section of the map. Then, we rev'd the car, under no load, and took measurements with a Snap-on Tools timing light with the wasted-spark adapter to ensure that the timing was stable. For hall effect, which doesn't tend to drift, it was rock solid 10 degrees.

Getting agressive with timing is now not so risky. I know that what I set the timing to is pretty much what I'm getting. Of course, I'm monitoring knock all the time regardless whatever timing I'm running.

-scott
 

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Discussion Starter #10
I check timing sync on every car before I tune it. The cars w/o external adjustable timing I've found are pretty much spot-on. Of course cars with Dizzys, adjustable CAS, etc need adjusting. So I'm sure thats not the case.

And what do you mean by "AFRS the ECU gives"? I have logs of AFR and timing from stock ECUs...and I'm comparing to AEM logs.
 
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Taffy said:
Are you sure that the timing is corect on your EMS? The AEM EMSs are notorious for not haveing the same timing that it says. This is a sync problem. Check your actual timing with a timing gun. You might be running more timing that you think.
The nice thing about the 2jz, is that the timing is not adjustable. So as long as you don't go in there and try to sync it up...your fine... NEVER adjust the base settings timing sync on the EMS with a Supra....EVER! You will be wrong if you adjust it.... Contrary to pupular belief...timing lights will Lie to you.
 

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It looks like the stock ECU bases timing on knock sensor feedback alot more so than AFR.

Does the stock ECU use high/low knock tables intialized to a max value, and when the knock sensors fire off they just adjust down? The differences in the way the AEM and stock ECU process and respond to the knock sensor data could be very different.

It's a good question, and I'd like to know more about how the stock ECU and AEM differ when it comes to adjust timing real time based on AFR, knock sensor feedback, etc...
 

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the stock ecu jumps completely out of the timing map if knock is detected beyond a certain point (almost any) and goes to another map. You'll notice this if you run pump gas with a g-force ECU. No matter what timing map you have put in, the timing goes back to the same value when knock is detected. Run race fuel and you will see the modified timing map values. My original 93 ECU was way faster than my g-force on pump fuel because it was less aggressive with timing retard under knock. The stock ECU also drowns the engine with fuel. Most other Toyota ECUs work similar to the AEM and retard from the base map depending on severity of the knock. The big difference is the hysteresis of the stock ECU for knock sensor noise is much more refined therefore better at handling knock.
 

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Discussion Starter #16
JZ19- is that only for OBD-I? Reason I ask is because I have seen OBD-II ECUs pull as little as 1 deg and as much as 7 deg before-- and everywhere in between. This leads me to believe its retarding/pulling, not jumping to some static 'knock' map.
 

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Yeah phorce, that has been my observation as well.

I would think the stock ECU would maintain hysteresis for adjusting timing up, as opposed to down. And that once knock is detected the ECU would adjust timing down by constant intervals until knock is no longer detected. Then, it would attempt to adjust up recalling where knock originally occured.

It could have to do with simply the rate at which the stock ECU firmware samples the knock sensor data. Faster samples with a high priority task could react quicker and with better resolution. Of course it could also be the analog to digital coversion, filtering etc..., that the stock ECU or AEM is doing from the knock sensors that make the end result different.

Of course I'm specualting, it would be nice if we had the ECU code and could look at it along with the AEM code.
 
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All factory ecu's when they detect knock are going to make aggressive changes...they have to warranty the engines....remember. You could easily make the AEM perform like the stock car, except the AEM will instantly put the timing back in when knock is gone, the factory (depending upon the manufacturer) can keep timing out for as long as an entire tank of fuel, then put it in once it see's that the tank has been re-filled.
 

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I am used to AEM timing numbers. My eyeballs almost popped out of my head last night when I was datalogging the timing on a friends OBD2/MAPECU BL74 car. 24+ degrees of timing on 18 psi with a mix of 114 and 93 pump octane. Seems stupidly high to me since it was giving him less timing when his car was BPU with 100 octane but, it wasn't pulling any out and the EGT never went up all the way thru 4th gear. I've got to get mine running again and see how carried away I can get with the timing on AEM, running it pig rich on straight C16. Maybe more power than leaning it out and running less timing...
 

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Discussion Starter #20
Yep..its very common to see 20-23deg of timing on a stock ECU supra, with race fuel...even at peak tq! And thats WITH proper AFRs.
 
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