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90mm DBW on RB25 - No response

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Ive tried to work this out for almost 6 months, we have tried all enrichments variables, tests, so many test that i just gave up....

* 490hp RB25 Neo with a ECUMASTER Black

I put a 90mm LS3 DBW Throttle on it, its a drifting car, everytime i go WOT or make decent TPS changes, the Throttle opens up, AFRs go lean and then stabilize after lagging for response.

ive tried many enrichments tests, the closest ive gotten was getting a thin spike of lean with 6 out of 10 rating of throttle response, sometimes (due to quick throttle changes) AFR just go over 10 and the engine chokes on fuel, then if i start restricting by dTPS rate, RPM rate, TPS rate, max enrichment, enrichment sustain rate, i just start getting leaner and getting worst of response again. I have not been able to ever get decent response on this throttle, i just use it taking into account the 1-2 segs lag that i get.

You would think a middle ground could be found, but the enrichment percentage that i use to get a 6 out 10 response from the engine is around 130% increase of fuel, less than that and i get lean and worst response, more than that and it chokes on fuel, trying to get short bursts of fuel didnt work, increasing sustain rate, increasing TPS polling rate, so quicker respond to changes, scale enrichment by rpm up down, i swear ive tried all combinations i could think of for 6 months...

Im going back to stock throttle with cable.... But i need to know, is there a point where the throttle is just so big that the engine is unable to regulate AFR in any way? Cause i seriously spend months trying to beat this condition and logging, testing testing testing and nothing ever came close to the response i had with a Q45 Cable throttle body....

If the ECU lets you use TPS as the input to the main fuel map (like Alpha-N fueling), that can sometimes help reduce the amount of accel fuel enrichment needed. Be sure you still have compensation for manifold pressure if this is a turbocharged engine, sometimes that's called '4d mapping' when the ECU uses both throttle and MAP for the fueling calcs. Also look into adjusting the injector firing angle / phasing. If the injectors fire too late for the fuel to get into the cylinder, the engine can act like you've described. Try making big changes (over 50 degrees at a time).

When a throttle is too large for the engine, the engine will make max power even at very low throttle angles like 30%. If the engine makes max power from 30%-100%, your foot doesn't actually have control of the engine power unless you're between 0-30% throttle angles. Same engine should make the same max power from 70%-100% throttle on a smaller throttle body, and you'll have much better control between 0-70%.

Hmmmm thats one variable i havent messed around with, heres an example of what i usually see and feel. See picture attached

I open TPS, DBW responds, acc enrich comes on, you can see the injector DC reacting, AFRs go lean and RPMS dont rise, engine lags, a mess. Ill retry from a basic setup again to see if the angle thing changes it up and then retake the enrichment values to the playground.

Attached Files

So after testing injection angle i saw no change. But i did update the ECU and i seemed to gain a max enrichment limit of 255%. Last time i only could go up to 130%. Dont know if it was because of another table establishing the max limit but..... i finally have throttle response and a nice feeling. This was using a 255% enrichment value almost all the time the throttle opens up.

Even touching the VE table for low rpm high load didnt help, because it only made the car go rich under slow tps changes.

So yep. Problem fixed so far, now i gotta fine tune it and test it while drifiting

Well, i tested it extensively, didnt work, i got it to respond somewhat fine, but AFRs were uncontrollable during drifting no matter how much i fine tuned. The DBW motor seized (ebay one) and i got stranded and robbed. So that was the last straw, took it off, went back to stock throttle. To my suprise, i still had the damn lag! But this time around using enrichment gave it back and it doesnt overshoots the AFR target range, the engine feels responsive and goes to red line without hic cups. Going back to normal settings i get the lag again but it then responds correctly, enrichment gives me back the instant response without bogging down as the other throttle did.

Guess i gotta learn a bit more but using the stock one seems to be the most comfortable solution for me right now.

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