The 94 eg cx hatch I just bought came with a d16y8 swap with the 1994 stock harness and stock ecu. The engine is completely stock and will remain so for awhile at least. It runs, but vtec doesn't work, the redline is way too low, and it runs rich all the time. I know almost nothing about engine management so what would be my best option? Should I rewire the whole car with a d16y8 harness and a p2p ecu? Would a xenocron p28 with a basemap for a d16y8 work as a permanent option since the engine is bone stock, or would I need a professional dyno tune? I'm looking for the cheapest/easiest possible option with the idea that I might turbo later down the line. I'd just like to get it working the way it should, but if it costs $50 more to buy a p28 with a basemap that would work just as well as a rewiring of the whole car, I would be stupid not to get it just because of the upgradability.

 

Sounds like ecu is in limp mode. Which stock harness? The CX or Y8? P28 ecu itself should work fine for this without any modifications.

 

Its the cx harness, and are you saying the p28 with the basemap I mentioned earlier or a stock p28?

 

If it is stock CX harness, that's gonna be OBD1. You'll need the proper harness for the Y8, if you don't have it already. Then OBD2 to OBD1 adapter.

 

A stock P28 should work just fine. Just get your engine harness issue resolved, get the OBD2 to OBD1 adapter, grab a fresh P28, plug and zoom.

 

What's involved with the harness swap? is it just plug and play or are there new sensors I need to install and custom wiring and stuff like that?

 

The harnesses are a bit weird for me with Honda. This is not a NORMAL swap, but it can and has been done. Most people opt for the Z6 rather than Y8 since they are nearly identical, with the exception of the combustion chamber; but the Z6 is OBD1. It's a steeper hill to climb, but I haven't looked much myself into this particular swap mix. Maybe somebody with a bit more info on that part will chime in soon

 

It is not possible to use the Y8 engine harness in a '94 Civic chassis... well, possible... but it is completely ridiculous to try. Simply use the CX engine harness, use the T/B and fuel injectors from a Z6 engine, wire the VTP and VTS to the passenger side chassis harness/engine harness junction and then on to the ECU to the proper pin locations, plug in your P28 (stock or chipped) and you will be good to go. The only adapter needed will be for the distributor to plug the Y8 dizzy up to the CX engine harness, unless you find an old D15B7 distributor that will plug in directly to the engine harness, in which case no adapter is necessary.

 

The cx harness is already in the car and works. I have been driving the car around for about a month now and other than the rev limiter being too low, vtec not working, and it running rich all the time, it works fine. Do I still need to do all those other things for a p28 to work, or will it work now since it already works with the p05?

 

That ECU **MAY** be in limp mode even though it works. The car can be driven, but with limitation, Is your rev limit like, 3500? What's your rev limit now?

 

The rev limit is currently at 5800 rpm

 

Then unless i'm mistaken, VTEC should be engaged by that point however, if you're hitting rev limit, you won't really notice it has, **IF** it is at all. Working on a P05? Not very well. Still going to have problems. P05 is a non-VTEC, 1 wire O2, 8 valve setup. Honestly, it'll run like hammered **** and if you were doing that, you may as well get a P06.. At least it's 4 wire. Still non VTEC, but would have better fuel maps than the 05. But again, it still doesn't solve the issue of your engine harness being wrong Get some research in on the things you need to change about your engine harness, like the distributor plugs, O2 sensor, etc.. If you were feeling REALLY froggy, you'd replace the harness entirely then get the OBD2>1 adapter.. Depends on how much frustration you wanna deal with lol. Rummaging through junkyards, i've seen SOOOOOOO many Hondas out there that were clearly swapped, just didn't appear to be done properly, I.E. non-chipped P05 and P06 ECUs on Z6 swaps, wiring that would leave ANYONE remotely electrically inclined scratching their head, etc.. Hack jobs that ended up getting junked. Sad. You're a brave soul for purchasing a swapped car to begin with, let alone one that clearly had issues.

 

Would the p28 work on the harness just plug and play do you think? I'm probably not going to have this car for very long so I just want it to have a higher rev limit, hit vtec, and maybe run less rich so it doesn't backfire everywhere. I will rewire the car if its absolutely necessary but I'm clearly pretty new at this and would prefer to keep it simple so I won't mess it up.

 

The plugs that you plug into that ecu directly will not be equipped with the wires needed to properly run that engine.

Refer to my above recommendation.




This is absolutely necessary to achieve your desired results. This is also providing your current ecu is, itself, in good working order..
Wiring up what you need is MUCH easier than it sounds. The cool thing about honda harnesses and ECU stuff is that the harnesses are at least pinned for stuff they aren't equipped with, just lacking the ECU components; I.E. non VTEC ECU is pinned, but missing the resistors/transistors whatever inside, etc. Heck, there are kits available to convert non VTEC ECU into VTEC.
Anyhow.. The basline operation is already there, you just need to complete it. Plugs and wires for your distributor, O2 sensor, VTEC solenoid, etc. You're going to have to wire it or you're going to suffer a shitty running car. No way around it.

 

Ok, thanks, you said earlier that a z6 harness would work best? or a y8 with a obd2 to obd1 adaptor?

 

Here's a good read to get you started!
https://honda-tech.com/how-tos/a/hon...d-plugs-378236

 

Or if you really don't feel like messing with any of it, you can message me a price you'd sell the car for and depending on your location, I'll certainly consider taking it off your hands