mark19401

98 civic lx automatic 1.6 with 144k. The top o2 sensor is wired directly to the computer. Is there a reason someone would do this or did they not know what they were doing? Is there a remedy? It runs rough and hesitates.

grumblemarc

iTrader: (4)

What does that have to do with the lagging?

hyperblu

grumble strikes again with yet another worthless post... The upstream o2 sensor will cause driveability issues. The upstream o2 adjusts air fuel ratios and will cause hesitations, erratic idle, etc. It is possible there was a damaged wire somewhere in the harness that was cancelling the signal to the ecu. Is the check engine light on?

BryanM.

iTrader: (1)

grumblemarc

iTrader: (4)

Okay. The O2 sensor sends it's signal to the ECU regardless. What YOU don't know is that there is a hacked up wiring harness also to take into consideration that may be causing the issue so it's more than likely THAT is the problem and NOT the O2 sensor itself.
So please, enough with the personal attacks already. I don't like you, you don't like me. Get past it.

What ELSE is going on with this car?
When was the last time this thing had a full tuneup?
Not really enough info to start diagnosing the problem with the lack of info.

hyperblu

Incorrect. The ecu does not use the signals until operating temperature.
You dont even know me, and you act the same ignorant fashion to everyone. You make ht what it is today.

grumblemarc

iTrader: (4)

I don't care if the ECU doesn't use the signals until a certain time. I said the sensor sends signals to the ECU so what does it matter that it's wired directly to the ECU?.

The OP needs to take care of that hack job wiring before he starts trying to diagnose problems with various parts.

And what do YOU know about H-T? You haven't been here but a hot minute.

hyperblu

And how exactly would you know how long ive been here? below my username? haha... and really... What DOES it matter if it's wired directly to the ecu? It goes directly to the ecu through the harness does it not? Making a new wire to the ecu is not a "hackjob". Twisting two wires together and taping them is a hackjob...

grumblemarc

iTrader: (4)

Like I said. OP. Fix your wiring issue BEFORE you start trying to diagnose issues with parts that may or may NOT be faulty.

hyperblu

Who said anything about a wiring issue? He said the o2 sensor was rewired directly to the ecu. The wiring could be flawless for all we know. OP we need more info. it is possible your IACV is dirty and causing the drivability issues and your o2 sensor is fine...

grumblemarc

iTrader: (4)

I guess I have to quote it twice.

hyperblu

Strange to him. The honda dealership I work at doesnt replace a $1050 harness for a short. Im a tech, not a backyard mechanic...

grumblemarc

iTrader: (4)

Like I said. Fix the wiring, which INCLUDES the hacked up 02 sensor wires, and the problem will more than likely go away. If not then that's just one more thing repaired that you know is working as it was designed to.

mark19401

Thank you for all of the answers. Yes, it's been tuned up, new plugs, wires, fuel injectors, timing belt, water pump and o2 sensors. The wiring is a hack job (things wired wrong and connectors not plugged in to anything) so it seems like it's a matter of redoing the wiring. I had a few techs at honda look at it but were stumped. They called an "expert" in today so I will see if he can figure it out.