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-   -   Need help with a tune (https://www.rx7club.com/general-rotary-tech-support-11/need-help-tune-1171415/)

valvestater Oct 3, 2025 11:59 AM

Need help with a tune
 
88 rx7, NA, Haltech 550, IGN-1a setup, half bridge

I have gotten the car to start using the stock mazda pressure sensor. I guessed on the calibration numbers but i got it to idle fine. I was having the issue where when i even pressed the throttle a tiny bit, itd sputter and die (from going lean). I have been screwing with transient throttle and map prediction but i CANNOT get it to stay alive when i press the throttle more than a tiny bit. I even switched over to haltechs built in map sensor (which i assume would be more accurate) and now the car starts, idles for 5 seconds, then slowly dies. Need any advice

j9fd3s Oct 3, 2025 12:23 PM

well you have choices, i think a lot of people would do an NA using the TPS instead of the MAP sensor, its a little easier to tune with a big port.
or you can keep tuning with the MAP sensor, with a big port there is going to be some non-linear spot (i would think), so its not going to be the easiest thing, although its possible

oh and the other thing is that Mazda puts the MAP signal in a runner so it has all the pulses, if you haven't you want to find a vacuum nipple that sees signal from after the throttle body. you could tee it in with the Fuel Pressure Regulator

dguy Oct 3, 2025 10:33 PM

Run it Alpha-N as suggested. I'd also use the onboard sensor for MAP compensation under cruise etc, not the factory sensor. Other than those suggestions without looking at a map theres not much people will be able to help you with.

notanymore Oct 4, 2025 06:40 PM

save your maps step by step, and remember, more fuel correction is better than less. engines likes gas, they really despise lean conditions especially under transient conditions.


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