Hello,

I own a 2002 Honda Civic EX 1.7 L with the D17A2 engine with an automatic transmission. I recently replaced the engines computer (ECU) as the old one was failing. The replacement ECU was put in by the local Honda dealership and programmed. Since then my car has been running quite a bit better but is still running fairly rough. I scanned for codes but the only code that comes up is a code for the O2 sensor as expected since it is unplugged because one of the wires is broke. So these are the major symptoms that my car is producing: poor acceleration (revs high) , spits & sputters, makes a popping sound kind of like pre-ignition or pinging and also shifts hard. I've replaced all of the spark plugs, checked my charging system, checked valve timing and replaced the throttle body with a known good functioning one but my car is still running terrible. I even removed the fuel pump from the gas tank to see if the fuel filter was plugged but it was completely empty. The only thing that I can think of now is that maybe my EGR valve is failing by being stuck open or closed from carbon build up. Would a failing EGR cause these problems? I'm going to attach two YouTube videos of what my car is doing. Any help with this would be greatly appreciated!


Now if you're wondering why my RPM's are fluctuating so much is because I don't like when my car rev's like that when I press the gas to accelerate. When I press the pedal my car wants to over rev to accelerate.

 

Which sensor's wires are broken? Primary or secondary? And which exact code? I just fixed a similar issue with my roommate's car in this thread a few weeks ago by 'inspecting' the catalytic converter: https://honda-tech.com/forums/honda-...ution-3308002/

His was clogged. Might be worth checking out. It made the same noises as your car. As for now, if it's the primary sensor that you're having issues with, you'll have to fix that first before we can go any further. It can and will definitely jack some things up if it gets the chance. And if it's not your converter now, running that bad COULD mess it up and cause issues in the future.

And when you say you checked valve timing, do you mean the mechanical timing and adjustment of the timing belt?

 

I had the converter out about 6 months ago as I suspected that it might have been clogged but it wasn't unless it actually is now for whatever reason. The O2 sensor that is broken is the one below my exhaust manifold not the one on the cat itself. I've attached the code below. So by checked my timing I made sure that the top pulley was still TDC (UP) & that the notch on my cam shaft was lining up where it should be every rotation. I guess I'll cut the CAT out again and inspect it.

 

Glad timing seems alright. But you're gonna need to fix that first sensor and get back to us. The first one actually affects the fuel trim in closed loop mode. The second just monitors how well the converter is cleaning things up. We can take things from there if you still have issues. Just remember the longer you run it like this the more possible damage can be done to the converter.

Is it just a broken wire where you can solder, heatshrink, and call it a day? Or is it literally broken at the end of the sensor where you need a new one? These cars don't really like anything but an OEM or Denso sensor if I remember correctly.

 

it might be your map sensor. I have a similar issue albeit my car doesn't run that bad, then again I don't really force it like you do, you shouldn't drive your car at such a high rpm...get it fixed. check to see if your check engine blinks...that translates to a mil code. If you have a service manual check to see what the problem is...When I scanned mine it didnt give any code after I replaced my o2 sensor but it was stalling shortly after I did install it. It's probably the map sensor. you should check that....but for sure your first step should be replacing that o2 sensor and then taking it from there...a bad alternator can produce similar effects, except with a bad alt, the car turns off and really stalls bad. you can't really force it like that....

replace the o2 sensor...

 

Just an FYI, replacing the O2 sensor fixed the issues that I was having. The O2 sensor that was bad was responsible for my fuel trim and the wire on the sensor was completely cut. I replaced it with a cheap one from Amazon and it worked fine after that. Thanks for your help!