neoc03

Basic Rundown:
Car is a 2000 Honda Civic SI. Turbocharged running eCtune. Just replaced fuel filter so I know that isn't causing the issue.

Here is what happens:
When car is cold it starts right up runs like butter holds perfect idle.

Once it reaches operating temp I will be pressing the gas and all the sudden loses all power. You can hear it start to sputter really bad for about 3 seconds then it just cuts out. The car won't start back up while it is still at operating temp. However once it reaches a temp below that it fires right up and acts just fine.

Any Ideas?

Former User

Any CEL codes?

Check whether unplugging the primary O2 sensor eliminates the problem.

hondamark35

i've had similar symptoms with a 91 Integra recently. after a lot of tail chasing... i discovered the cat. converter was 80-90% clogged! the 'honeycomb' material had melted. i haven't test driven it with a new cat yet, but with the way that one looked... it's no wonder it struggled!

drop that cat down and have a look.

neoc03

No CEL as usual. CEL light is working. I will try unplugging the 02 sensor first thing tomorrow. I did some reading and saw that going into closed loop and the 02 sensor is on it's way out it can cause these problems. Shouldn't that kick a CEL though? Will the car run fine with the primary unplugged since it's a specific written tune? Thanks for the quick reply.

Former User

Bad O2 sensors don't necessarily throw a code.

neoc03

Cat is gutted so I know it's not that. So what will the car do when it reaches operating temp and doesn't get any input from the 02 sensor it's looking for?

Former User

Stock set up would just run rich after unplugging the primary O2 sensor. Not sure what the effect will be on your tuned set up.

neoc03

So if the car runs fine it's obviously the 02 sensor.

Former User

neoc03

Thanks for the help again.

neoc03

Just as a follow up the primary was already unplugged and capped. I unplugged the secondary and like magic it's behaving again. Very rich though to the point I can smell it at a stop light. New downstream sensor comes in tomorrow.

Former User

The secondary O2 sensor has no function whatsoever in determining the air:fuel ratio. Therefore, my guess is the primary and secondary O2 sensors are swapped and that the secondary O2 sensor was originally unplugged. Double check the wires.

farfrumugen

ignition module

Former User

This is definitely possible.

neoc03

The wires ran up into the cabin right above the 02 sensor after the cat. The actual pigtail connection was inside the car right behind the cupholders. The pigtail wouldn't be able to reach the primary sensor. Car was just at the tuners for headwork. I guess they may have just left it unplugged on accident. I'll crawl back under there tomorrow.

What function does the secondary 02 sensor serve?

Former User