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Transient tuning.

Practical Dyno Tuning

Discussion and questions related to the course Practical Dyno Tuning


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I'm about to give up over here. I have a is300 with a 1jzgte vvti, I'm using a piggy back setup on a ecumasters classic. I get the idle afr and cruise afr right where I want it but I can't press the pedal more than like 2% without the car pretty much dying which is obviously pretty dangerous while driving.

If I turn the accel enrichment off all together and even slightly touch the pedal the car dies. No matter how much accel enrichment I add the car will stumble and go full lean. If I adjust the VE table around 12 afr, the problem gets alot better but obviously isn't good for idling.

Just so I'm 100% clear, do you have the ECU Master ECU in complete control of fuel and ignition? From what you've described it sounds like either you've got some major issues with the calibration of the main fuel table, or there is something else going on here related to the ECU operation - Perhaps wiring or a triggering issue. It's hard to say with such limited info to work from.

It's vital to get the main fuel table dialled in before worrying about acceleration enrichment as the accel enrichment function as a modifier on top of the main fuel table. This means if the main fuel table is wrong, there's little chance to fix this with accel enrichment.

Sorry, the Ecumaster has direct control of the ignition and injectors(the reason for this is the car is an auto and needed to keep some functions to control the auto), and shares the other sensors. The car starts up fine, has no sync issues.

After I wrote this message I started over with a base cal. I turned off every enrichment and started road tuning, I found as long as I really really easily pressed the pedal I could get it going without it spiking lean. The car drives great and afr's are near perfect from idle to cruise. Even with the Afrs where I want them, at idle if I just hit the throttle normally the car will go lean and die. So I increased the cells that were used during this acceleration and no change.

So as I felt good about my table at this point, I started looking into accel enrichment. I wanted to try and make it go the other way by making it go rich at accel and then bring it back. First I set my parameters at 3% dtps rate to turn on, enrichment limit 100%, enrichment sustain 25%. Turned enrichments up to 100% and still goes full lean. Increased enrichment limit to 255%, still goes lean. Changed sustain limit to 95%, and now it revs! but only once and then will go lean if I do it again in quick succession. The problem now is it will go rich after accel and then rich. There's no way that these settings are normal.

Is there something mechanical I should be looking at? Like I said everything else is fine and responds to adjustments how I wan't but quick throttle changes. So weird.