During this last summer my fresh SOHC ZC, I retained the DPFI, swap decided to start bogging down under acceleration (I swear it is because I hit a rattle snake @ 70mph lol). It would only happen after the car warmed up. After a weeks of this it finally started throwing code 1 (O2 sensor). As soon as it would throw the code, the bogging went away. At this point I just unplugged the O2 sensor and the problem went away. Fast forward to two weeks ago. It started bogging out again on the way home from work. It was struggling to do 50 mph but again as soon as code 1 is thrown, no bogging and it drives normally.

Finally last weekend I did the MPFI swap. Everything was fine until today. I drove 31 miles to work problem free. On the way home it bogged out really bad for about 4 miles until the code was thrown and it began running like the true champ it is. So...

Bad O2 sensor?
Cat clogging up (it is 23 years old lol)?
#2 and #3 valve seals leaking oil onto spark plugs the cause?
Something so simple I should punch myself in that face for not figuring out?


I am too busy with work and don't have the cash to throw at this car right now so, I figure I would get some opinions from you guys.

 

Possibly bad O2 sensor. Is it a 1 wire O2? I have a spare one I'll send you for cheaper than the parts store if you want it.

Cat could be clogged, but you'd probably notice some smoke from it. You can check the cat with a laser thermometer thingy. It should be much hotter after the cat.


The leaking could cause the spark plugs to blow out, check your plugs. Try new spark plugs and pull them and post photos after it starts to bog. Someone can read them for you and tell you what looks to be the problem.

Something so simple, yes, possible. Check the valve cover ground, transmission to chassis ground, and the thermostat ground. They are important and often the culprit. Check the distributor cap inside for cracks that could cause misfires. Check your spark plug resistances and replace the spark plugs. If it is bogging down, and you have a moment to spend troubleshooting it, check for misfires while it is bogging down.

I know you said it would bog pre-MPFI conversion, but check your extra wires anyways.

 

Try changing the O2 sensor and plugs, I've had a similar problem in my crx and it turned out to be the fuel pump. Don't overlook anything check your wiring and the cat as well. Try posting a video of when it starts to bog and after it stops.

 

Agreed, don't get stuck on one area. Keep the thought in your mind, "What could it possibly be?"

First thing before throwing parts at it, barrow a fuel pressure gauge and check it while driving. Recreate the problem and check your fuel pressure. Sounds like the fuel pump to me.