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-   -   Off throttle fuel pump response incorrect (https://www.miataturbo.net/engine-performance-56/off-throttle-fuel-pump-response-incorrect-104380/)

Jgilby 12-19-2020 08:23 AM

Off throttle fuel pump response incorrect
 
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Hi everybody, I will be making this thread to log this issue that has progressively become worse over time. Hopefully it helps someone down the road.

CAR- 92 Miata, Megasquirt, built bottom end, dw injectors and pump, garret turbo, and a few other go fast bits.
ISSUE- The issue is very inconsistent, making it very frustrating to try to solve. Whenever I let off the throttle, I can hear my fuel pump relay buzzing (AKA "Circuit Opening Relay") and this buzzing causes the fuel pump to just spit out fuel inconsistently and not cut fuel like programed. It will buzz sometimes when the key is in the on position. It will also buzz more when the car is at cruise at lower rpm. It is fine at say 70 mph. It varies a lot but for the most part throughout the entire rpm range, I can expect this buzzing whenever off the throttle. My immediate solution is to downshift and that will seem to immediately solve this issue until the next gear, if I don't and just take the car out of gear to come to a stop, the car will die. When I let off throttle and come back on it, it takes a sec for the fuel pump to catch up, and when it does, its very violent. The whole car jerks due to the fuel pump.
SOLUTIONS I'VE ATTEMPTED- I've replaced the fuel pump relay, shot for shorts in the wiring, cleaned grounds, checked the fuel pump.

I am starting to believe that it cold be a tuning issue since I had my car tuned around 9 months ago. Unfortunately, my tune was rushed and I am in need of a new one. I am going back today to try to shoot for shorts again thinking I may have missed one. I'll link my tune down below as well.

Does anybody out there have a clue what could be going on? Cause I am running out of ideas.


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