I have a stock D16z6 w/ manual transmission on a 95 EJ1.
Whenever I shift a second or two later the RPMs drop by about 500. Almost like there is a loss of power or something. This doesn't happen regularly and I don't believe it is my shifting as I usually match RPMs. Additionally, I know what it feels like whenever I mess up the rev matching and this is not the same. When this does happen it does sound like my car is struggling to go up in RPMs. Recently the same issue has come up while driving and already in gear. I would go to accelerate and it sounds like my engine is trying to go faster but the RPMs are barely creeping up. Or sometimes I will accelerate and the RPMs go up but then while hitting the gas the RPMs would attempt to adjust and drop?
This isn't always consistent as sometimes the engine feels strong and performs per usual.
Any ideas on what is going on?

 

It sounds to me like an air, spark or fuel inconsistency. I have been having a similar issue for years. I’ve been working towards resolving it, and I’ve improved it significantly, but I get a bit of a “stumble”, or sort of power cut daily now, usually while cruising around 2500-3k rpm. Previously I replaced cap and rotor, coil, plugs / wires, fuel filter and pump. These were done over a long period of time, and I had considered most of it maintenance items, as most of those components hadn’t been replaced for some time anyway. At this point, I’ve ordered a walbro 255lph fuel pump, since I’ll eventually be tuning and hoping to add some power to this little D16y8, and my next replacement / upgrade will be some FIC injectors, as I believe that’s about the only thing I haven’t replaced yet. In my mind at least, the injectors being original and perhaps “dirty” logically makes sense that could be my issue with presenting itself most often at cruising speed / rpm. I rarely notice any issue during acceleration, and no CEL has been set (recently). Even scanning for codes doesn’t show me anything. I have seen some dubious STFT data when I’ve logged that, but never have caught it while the problem is actually occurring. Crossing my fingers that new Injectors will alleviate my issue.

ETA: forgot to add: O2 sensor and coolant temperature sensors are also a significant part of how the engine runs, how much fuel is delivered, etc.. so if you haven’t verified especially the O2, that may be worth a look. My O2 is fairly new, replaced when I did head gasket 2 years ago. I’ve replaced one coolant temperature sensor, and the other one is in my cart to be installed, but haven’t got to it yet. My thermostat was replaced a couple years ago, with a store brand and I’ve got an OEM one now, which I’ll be replacing when I do the other temp sensor. I do sometimes notice inaccurate / inconsistent temp readings from the cluster gauge, and suspect the store brand thermostat may be the reason. This could potentially throw off A/F trims, but not sure if that’s my problem.

ETA#2: The fuel pump was also replaced probably 4 years ago with an OEM, which I expected to address this, but didn’t seem to make any difference.

**also, I’d love to hear the forums’ consensus on the coil pack conversion. I’m considering doing this at some point as well. Might be nice to go away from a distributor based spark system and go with coils.