I been getting a CEL at least once a week the past 3 weeks lately. I have on Nismo Intakes, Berk HFC's and HKS True-Dual, but nothing else. I had all these parts on the car for about a year now with NO issues whatsoever. When all of the sudden 3 weeks ago, going to work, I went WOT on a empty stretch of road. Then right after I calmed the car down, CEL came on (or at least when i first noticed it). It drove fine the rest of the way and on the way home that night.

I got home, reset the light and it's been fine for a week. Then coming home the other night I gave it a go again and sure as hell, CEL came on again during a WOT run.

I reset it again after I got home. Started the Z back up and gave it full thottle, redlining it in the driveway. Nothing happened, no codes thrown or CEL light. Then I was driving it last night on the way home and tested it again by going full bore, it threw it again. It seems like normal driving, it's fine. If i go WOT it comes on. But I had this setup for a year already, nothings changed and I never had an issue till now.

I know I do not know the code because i have not had the time yet to go to nissan or autozone or have the means to pull the code. Unless there is some sort of method I don't know about like reading the CEL flashes in a debug mode, like I did on my old intergra years ago. But by judging from what im saying, what do you guys think? O2?

Thanks

 

seems like it..maybe the berks are messing with it!

 

^^+1 to the above , you may want to check out the 02 sensor on the berks , check for crack too around the hfc .

 

Thanks guys. Ill try to check it out asap. Its snowing here now, tomorrow and monday, so ill get it on ramps as soon as i can. Ill let you know what i find.

 

You should clear the learned fuel trims off the ECU first. What is odd is that during WOT the ECU is in fuel enrichment mode, meaning that it does not compare the O2 readings at the secondary O2 sensors (ones in the cats).

If it is a HFC related issue, you will only get a CEL during cruisng when the computer is in closed loop mode (aka steady state driving at a constant speed). Shoot me an email and we'll get you checked out!

 

I did a total ECU reset both times with a battery disconnect. That should reset all ECU trims and mapping, right?

From what I can tell, after a reset IF I drive normally ( say never passing 4500 rpms or more than 25% throttle) the light wont go on. If I go past those areas, the light usually does go on.

It just snowed here so i cant get the car on ramps yet to check out the HFC's, but once the snow cleans off the driveway, I will. Ill post up and email you my findings.

 

Update: I got the Z on ramps yesterday and gave everything a look underneath. The berk HFC's look fine. No cracks or anything, no leaks, tight bolts, etc. O2 sensors are fine and tight inside the bungs. Everything looks fine after the berks too.

It smells fine too, like a car with HFC's should smell like. So the cat's didnt fail. Even if they did the ECU should throw a light the second I turned the car on, not only at full WOT.

Anyways, I reset the ECU with the pull the batt method. Drained out the charge in the system and hooked it back up. Turned the car back on and let it idle, NO CEL light. I drove it yesterday and today and so far no CEL light. However I have NOT gone WOT or all out yet. I have just been driving casually. I bet myself 10 bucks though if i head out right now and go WOT it will set off the CEL light again.

It really has me clueless. I guess ill have to go to nissan or autozone and pull the code.