nogas00civicdx

Ok so heres some background on the car. I recently bought a manual 2000 Civic DX with a B20Z2 swap. The previous exhaust setup was a DC Sports header with a rigged together stock exhaust. The catalytic converter wasn't connected to the rest of the exhaust so I had a new exhaust installed on the car (stock exhaust manifold with a test pipe and N1 style catback. The car was previously running fine besides the fact that it was obnoxiously loud. Ever since I had the exhaust installed the car seems to fall flat on its face in lower RPM's. I personally replaced the spark plugs (ngk coppers), NGK spark plugs, and distributor cap; the rotor button looked fine. I brought the car back to the shop that installed my exhaust to have them find the issue and it still does the same thing. They fixed some of the wiring on the o2 sensor, replaced the ICM, fuel pump, and fuel filter and its still doing it. I'm not sure what else it could be as I'm coming from the EVO world. Anybody have any idea what it could be?

NotARaCist

iTrader: (1)

Is the CEL on? Does it work? What ECU does your car have? Have you checked mechanical and ignition timing?

nogas00civicdx

CEL is not on and it does work. Car is on obd2. I have not personally checked any mechanical or ignition timing.

NotARaCist

iTrader: (1)

The car being OBD2 doesn't tell us what ECU it has. Remove the passenger side kick panel, and find the ECU code. It should be on a sticker on the ECU itself. Definitely check timing.

nogas00civicdx

p75..? Automatic. I know they swapped out the ECU's also with no luck.

nogas00civicdx

Is it possible that the cat on the exhaust manifold is bad?

NotARaCist

iTrader: (1)

Are you sure, or are you guessing? If you're sure, you're running the wrong ECU, which creates rich and lean spots. You would be best served (for the safety and longevity of your motor) finding the correct ECU for your motor, which comes from a 00-01 CRV. That shouldn't cause a noticeable bog, though.

Definitely check your mechanical and ignition timing. Also, check your spark color. It wouldn't hurt to check your fuel pressure, but I wouldn't recommend that you check your injectors...we can cross that bridge if we have to.

If the cat was bad, you would be throwing a code for it (assuming you have the O2 sensors properly installed).

nogas00civicdx

I'm sure, its P75. Just curious as to why it was running fine before the exhaust install and why its not now?

NotARaCist

iTrader: (1)

I have absolutely no clue, and it doesn't make any sense.

You said a stock exhaust was put on? Does it look something like this?

nogas00civicdx

Stock exhaust manifold to a test pipe then the N1 style exhaust

NotARaCist

iTrader: (1)

So you have part #2 in the top picture, and #6 in the second picture, correct?

nogas00civicdx

Correct.

NotARaCist

iTrader: (1)

And you have two O2 sensors, both plugged in, neither throwing codes, correct?

nogas00civicdx

Correct.

NotARaCist

iTrader: (1)

Try disconnecting the exhaust from the manifold and see if that changes anything (other than the noise).

So, the CEL comes on for 2-3 seconds when you turn the key to ON(II), correct? Assuming it does, check the mechanical and ignition timing. Maybe someone working on your exhaust bumped your distributor or something I've seen weirder.

Former User

Definitely check the ignition timing.

What was done to the O2 sensor wires?

If you unplug the primary O2 sensor, is the problem eliminated?

How old are the plug wires?

Have you measured the fuel pressure and tested the FPR?

nogas00civicdx

Not exactly sure what was done to the o2 sensors, I'll have to ask tomorrow. I haven't had a chance to unplug the primary and see what it does, but I'm assuming I should unplug it from the harness though correct? The plug wires are brand new (NGK's) and I have not tested the fuel pressure or the FPR but they may have. I'll get more information on these things tomorrow when I'm at the shop.

nogas00civicdx

Just picked up the car after a week of it being at the shop. They spent a total of 6 hours working on the car and said it was fixed and of course its not. They found ound the rear o2 sensor was wired incorrectly which I assumed they would've checked when they first installed the exhaust. Replaced part of the wiring harness (not sure exactly which part). I'm out of idea's here...very frustating.

tony_2018

This is an automatic?

nogas00civicdx

Manual. I went ahead and spent 5 minutes of my own time yesterday morning to jack the car up and unplug the primary o2 sensor from the harness...which I had asked the mechanic to do before. He said it wouldn't make a difference...and guess what? The car runs perfectly fine. Obviously there's a check engine light but the car runs like a gem!

Former User

Replace the O2 sensor.