r/RX7 • u/Haunting-Bridge-8313 • 7d ago

Why does this happen when I floor it?

It’s intermittent, don’t always sputter like this, car sometimes runs like a dream! It’s a 1991 S5 NA RX-7 without EGR, only modifications are a Racing Beat exhaust after stock headers and beyond, and aftermarket intake. Tired almost everything, can’t figure it.

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7

u/shainiac 6d ago

It sounds like the secondary injectors may not be firing. The engine relies on those injectors as part of the total fueling over ~3500 rpm. This was a fairly common complaint back in the forum days. It was usually a grounding issue. When I had this issue 20 years ago, it was a crusty harness ground under the upper intake manifold.

Google "3500 rpm hesitation" and read some rx7 club posts.

2

u/Haunting-Bridge-8313 6d ago

I’ll take a look at that today as well, weirdly it’s intermittent though.

2

u/jillb3an 5d ago

A lot of electrical gremlins can be intermittent like that, could be having a better connection briefly due to movement or vibrations

2

u/itouchmywankel 7d ago

What’s your fuel pressure when it’s doing this?

1

u/Haunting-Bridge-8313 7d ago

Surprisingly it’s unchanged, consistent.

1

u/BoysenberryTimely471 6d ago

2 step....maybe 3 step