Rep Power: 0

Hi everyone,

I'm reposting this here because I may have been in the wrong forum before. I recently purchased a '94 civic CX hatchback (5 speed manual) with 180k miles on the D15 block but with a new (2k miles) mini me D16Y8 head with chipped and tuned P28. The previous owner did the swap, not me. After driving it home, I started to notice problems with the wiring. The first and most obvious issue is that all the lights on the vehicle (headlights, taillights, dash lights, etc) all pulsate while driving and idling. This seems to happen in coordination with an engine surge when idling. The RPMs will fluctuate between 900 and 1500 or so, and as the engine surges, the lights get brighter.

Also, when looking under the hood, I noticed that a couple wires were cut and not connected to anything (see photo). I took the car on a road trip (150 miles) and it gave me no trouble other than the slight surge and pulsating lights, as expected. However, when I started the car on the last day, it ran very poorly. The fuel injection seemed to not be constant, as the car was silent when I wasn't pressing the gas, and when I was, it had intermittent periods when it was silent as well. It sounded like rod knock almost. It started loosing power and a bunch of white smoke came out of the tailpipe, so I had it towed to a shop. They said it was running really rich because my new spark plugs were black (also my fuel economy was steadily decreasing), but ultimately they couldn't get it to act up again. I drove it home and it's been fine ever since.

After doing some research on how to fix this, I cleaned the throttle body, I replaced all the spark plugs, I tested fuel pressure, I replaced my O2 sensor as the previous one was black (the one connected to the exhaust manifold, there's no cat in my car), and I tested my battery and alternator (voltage did fluctuate around 14-17 volts along with the pulse, however), and none of these were the issue. Does anyone have any advice or a place to start looking to fix this problem or what those wires do? Anything helps, total noob here I've been told to replace the voltage regulator and the fuel pressure regulator, but I'm guessing it's more electrical because of how the surge seems related to the pulsating lights. Thanks so much!

 
Rep Power: 211

TSB 99-029 (harness rubbing on the intake manifold bracket) might be the issue. Here is a link to the pdf that describes the issue and correction: https://ww2-secure.justanswer.com/up...4118_fyuse.pdf Though it's not your car's engine block years it is worth checking because the 96-00 head swap.

Engine running rich causes: https://mechanicbase.com/engine/engine-running-rich/
You might have read this or similar already? You may want to try removing all the newly installed spark plugs while the engine is cold (sitting overnight) and checking them for fuel/wetness. If you have an usb boroscope (snake inspection camera) that could be used to inspect inside the cylinders for fuel or abnormal soot buildup. You want to isolate whether it's happening in all cylinders or just in single cylinder(s). Usually, white smoke is most prominent on cold starts. Keep an eye on the coolant levels in the radiator and reservoir to make sure the white smoke isn't from an internal coolant leak (coolant leaking into cylinders).

Since the engine has been modified and chipped/tuned it might be difficult to differentiate between a common issue or the swap that is causing a rich fuel condition.