mrdrpep

91 CRX HF with b16 OBD0 swap

This happens with engine hot or cold, doesn't matter.

I'm getting misfire/bogging/hesitation as soon as I go up a slight incline at any speed. Larger, steeper hills do not seem to be an issue, but slight inclines over a period of time. RPM doesn't seem to matter either. If I continue to hold throttle in the same position, it continues to happen and doesn't go away. If I let off throttle, rev, and then continue, it goes away. It's quite annoying.

So far I've replaced plug wires, cap/rotor, fuel filter, and TPS.

Now I'm thinking injectors, fuel pump (or pickup,etc), pcv, or fuel pressure regulator (?) I'm really leaning towards fuel pump because I believe it's stock. When the tank is low on fuel, it makes all kinds of grinding noise when priming and continues to make noise throughout the cabin (when tank is below 1/4).

edit:
thought I should mention.. I'll try replacing the o2 sensor as well. I only have one o2 sensor and I think I should have two for this ECU. If I'm going down hill while engine braking for more than 5-7 seconds, I get a CEL indicating a problem with the #2 02 sensor (which I don't have). Never been a problem with regular driving but comes on if coasting in gear for an extended period of time.

shadybr

Does it bog when you get to higher RPM? Did you check spark plugs and see if any moisture is inside the spark plug chamber? I've seen a little moisture inside the spark plug chamber causing bogging. Not sure how it happened but once I cleaned it up the car had no more bogging. Good luck!

mrdrpep

I will look into that. I really have concerns with the fuel pump but this is such a weird issue and with very specific requirements to make it happen. For example, it will not do it on every hill or incline but it happens repeatedly on the same hills. And, on those same hills, it doesn't seem to matter so much on the speed/rpm. So it leads me to believe it points back to the fuel pump with the fuel level being off some how. But to make this issue even more strange, it also doesn't seem to matter how much fuel is in the tank...

arries289

It could be the fuel pressure regulator sticking at a certain off-idle vacuum level. That would explain why it does not do it at more throttle/steeper hills. I would put a fuel gauge on it and see what it is doing.

mrdrpep

The problem was indeed related to missing the 2nd o2 sensor.

I'm planning to boost soon, so I went ahead and chipped my ECU and put in a chip that ignored the secondary o2 sensor. I have a EPROMER 6 chip burner and BRE software so I can make my own tunes. Now it runs great. I still don't trust my fuel pump so I'm throwing in a 255lph pump soon