Tuesday, January 26, 2010 - 02:21 pm, by: Lew Radbourn(Marlew)
I have always wanted to ask this question to see what others think;
I always wondered what happens when you have a piggy back as well. When you reset your ecu and the piggy back is tuned to the old settings the toyota ecu has learnt does it stuff up all that money spent on getting the car tuned on the dyno?????? i recon it does. What are your thoughts?
Tuesday, January 26, 2010 - 05:07 pm, by: Daniel Clarke(Dieseltrain)
My thoughts are the Stock ECU has maximum fuel and ignition parameters . All your doing is intercepting these parameters and adjusting them . If the Ecu is reset , surely its a matter of short time before the stock ECU is running those same parameters again ???
Tuesday, January 26, 2010 - 05:16 pm, by: Austen Menze(Mercyfulfate)
I asked the same question a while ago, since the stock ECU is constantly learning I was wondering if it would just learn how to run pig-rich eventually.
Tuesday, January 26, 2010 - 07:58 pm, by: Cihan Aday(Cihan)
Well, the fact is that the stock ECU runs one timing and one fueling base map with pulse width and ignition corrections applied on top based on sensor inputs (TPS, cts, ats, o2, knock). Knock control is very basic with the 1JZ-GTE non vvti. Timing is pulled between 4800-6000rpm and some fuel is added if knock is encountered again. Thats the extent to which timing is altered.
Fuelling is altered by a maximum margin (probably %15-%20) up to 4psi based on O2 sensor feedback. Thats about 2.9-3v MAP input. Thats the extent to which fuel is added or subtracted when there's no knock being measured.
Removing sensors; delete the knock sensor and the ECU automatically goes into limp home mode, pulling 7-10 degrees ignition on boost. Probably also adds some fuel (as much as it would to counter knock). Delete the O2 sensor and the ECU adds in maximum fuel correction (%15-20) under 4psi or 2.9-3.0v.
So, why does it seem like tunes change when the ECU is reset? When the ECU is tuned with a piggyback its very easy to trim the MAP signal to limit fuelling and forget to mitigate ignition. One or two dyno runs with detonation and the stock ECU is already pulling timing and adding extra fuel. It doesn't know the car is being tuned, or what the AFR's are. It can't 'learn to be rich', there's no such thing. It only retards ignition advance and adds extra fuel if the tune is making the engine detonate. So the problem isn't the stock ECU, its the tuning device and the tuner not understanding how it all works (not that its complicated by any stretch).
It's easy to blame the stock computer. In my experience the factory knock program on the 1JZ-GTE non-vvti is good for 330-350rwkw before cylinder pressure and combustion noise, not detonation, sets its sensors off. The 1JZ VVTI is super-sensitive and will *always* interfere above 250rwkw. Even 0.5 degree off, it knows about it and re-models the spark curve to test and mitigate. The best knock program, by far, is the 2JZ-GTE non vvti program. Will handle 350-400rwkw and genuinely saves those engines without overreacting in many cases.
The early model 1UZFE knock program is OK for NA but not to be relied on for boosted applications. Easy to see when the knock program is actively retarding because the ignition output gets dropped and increased in regular intervals by about 5 degrees peak to peak (testing the water) as the engine is revved out. After a few runs the area's with no feedback get the full ignition curve, anywhere with feedback gets 2.5-5degrees less.
All of the ECU's use fuel and timing to mitigate knock, newer models are more sensitive and much less lenient towards basic piggybacks and crude tuning methodologies.
Tuesday, January 26, 2010 - 08:42 pm, by: Boris Siljanoski(Z2tt)
So then what is the talk about resetting your ECU helps you gain power (no piggy backs or nothing).
Even there is a thread on here that has a guide on how to reset the ECU saying that it somehow learns hwo you drive and tunes itself. What is all that about?
Since you mentioned Cihan the ecu cant learn to be rich, so why do many people say that resetting the ECU you can gain power since it relearns the fuel curve or something?
Also above 350kw when stock knock sensors can pick up knock from combustion noise, what do you do, is there replacement ones you can use?
Wednesday, January 27, 2010 - 08:34 am, by: Cihan Aday(Cihan)
A reset clears knock retard and makes the ECU relearn injection correction via O2 sensor (up to 4psi only) against its fueling base map. Also clears error codes relating to the automatic etc.
If the engine went through a bad batch of fuel or the knock sensors pump phantom signals and the car suffers from 'chronic' performance loss, then an ECU reset will restore performance.
Knock sensors react to valvetrain noise when it gets loud enough. Keep those shims tight. Generally 1UZFE's suffer most from camshaft / valvetrain wear related performance loss. 1/ looser shim clearances means less valve open time/area = loss in breathing = loss in peak power and overall performance (especially because the standard camshafts are tiny). 2/ valvetrain wear adds more and more noise until the wear process is arrested with good servicing. The noise is picked up and timing pulled by the OEM computer.
I've seen 6-10rwkw gain from a 1UZ with only a knock sensor block circuit installed. Actually fixing the problem would net 5-10kw more peak power and a lot more after peak power.
RE 350rwkw and standard knock sensors - they need to be deleted with a blocking circuit (resistor pack like thing). For a generic 1J build (single etc) its not too important to replace / delete them as that's generally the limit on pump fuel without expensive work anyway.
David Vaughan Goo Roo Relaxed, but no provincial. IS300
Wednesday, January 27, 2010 - 08:52 pm, by: David Vaughan(Davidv)
My recollection is that the ECU recalls only the last 30 or so starts. What it learns, it can soon unlearn if you drive differently. Drive twice a day and it is two weeks, so it can not get "stuck". Further, after a reset-and-blast, if you drive as you did before the reset then it will soon be back as it was.
Wednesday, January 27, 2010 - 10:19 pm, by: Cihan Aday(Cihan)
Im speaking from measurable, logged and tested experience. There's no indication that any 'learning' happens at all, under normal driving only fuel mixtures get altered from rich to stoich vs O2 sensor output on a continual basis upto a specific load (usually 50 - 100ms feedback interval and a combination of RPM and TPS limits or RPM and pressure limits for turbo applications).
After 10 or so minutes the O2 vs fuel is complete and the engine is running stoich mixtures that meet emissions and reduce fuel consumption, if you're running good fuel - ignition shouldn't be altered..
These aren't adaptive ECU's like modern engines, for example, which run multiple maps and a sophisticated knock feedback that tests the water on a continual basis.
Thursday, January 28, 2010 - 04:09 pm, by: Cihan Aday(Cihan)
Time consuming because you have to order shims from Toyota so the car sits for a while, but not challenging if you have the right tools for shim removal.
Well worth checking clearances if you believe the engine's down on power or you can hear the valvetrain noise.
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