Ok, my car -> 99 Civic SI w/ a 2000 JDM ITR motor running a chipped P28.

Lets see if i can make all of this make sense.

Recently, my car has been missing i guess you could call it; at first, after it would warm up, it would stutter at anything over 10% throttle or so. Sometimes just a couple stutters, then it would take off like normal, sometimes it would just struggle to go anywhere. Mind you, this was ONLY happening OVER 10% throttle, anything under that and it would accelerate just fine... slow, but just fine.

So, a few days ago... maybe a week?, i changed to an o2 sensor that, as far as i know, is in good working order. Since I changed the o2 sensor, now my car stutters randomly when cold and warm, until the CEL comes on. After it throws the cel, the car will run fine. I still have vtec, no misfire, no stutter, no anything. Pulls hard, fuel economy goes down a little bit it seems, but I havent really tested it.

So here are my questions.

Are code 9 - CYP Sensor (Cylinder) defective circuit or unplugged / defective sensor -
and code 17 - VSS (Vehicle Speed Sensor) defective circuit or unplugged / defective sensor related? These are the only two codes that the ecu shows.

If these are related, HOW are they related?

Why does my car run kind of crappy (misfire, sputter, what have you) until the CEL comes on, and then runs close to perfect?

I get different codes with the USDM ITR ecu that i have, but i will get into that in a different thread. I need to pass emissions this year :/

Thanks for any help yall can give. Need more info just ask.

 

Bump - Anyone? I know there are alot of these swaps out there...

 

possibly a common ground.. swap in known good sensors and if the codes persist then hardwire the sensors directly to the pin for them at the ecu plug... the reason it runs shitty until the cel comes on may be due to the fact that when the cel comes on the ecu realizes there is a problem and compensates for it and makes it run slightly better.

 

your CYP sensor is dizzy related hense the running shitty..the VSS I dont believe can be related. You need to go through an apply vlotage to the pins for the CYP sensor and see if there is a short. If voltage passes through fine then I would agreee with the bad ground.

 

Thank you. I will at least look at wiring part of it this weekend. I can't really afford, nor find for that matter, the sensors/parts that I need right now.

What exactly do you mean 'hardwire'? Run its own wire from the dizzy to the ecu instead of the wire that's in the car harness?

Also, does the cyp sensor work like an Abs pulse wheel? Better said, should I take the dizzy out and look for a certain voltage pulse as it turns?