Misfiring after CBE install

[thangcu35]

Hi guys, I'm a new member and just got my Z this last weekend. It's a 2012 with 20k miles. It has K&N drop in filters when I bought it from the dealer, everything else is stock. It drove fine and smooth. I decided to install FI CBE 2 days ago and this is when the problem begins. Immediately after installing the cat back, I reset the ECU and took it out for a test drive and these are the symptoms I'm experiencing.

- When it revs above 5k RPM, it runs out of breath, the RPM could barely continue climb. Noticeable power loss. More severe with higher gears.
- I hear some weird pinging noise from the motor almost like detonation when the above occur (I run 93 premium, fresh gas). It might be misfiring/breaking up and I'm interpreting it as knock.
- The SES light also begins to blink and then disappears after a few seconds. I assume this is the ECU telling me that it detected misfiring sequences that could potentially damage emission comp. etc catalytic converter.

If I repeatedly do the above for a couple of times, the SES will remain lit and pop a P0300 code. If I do not rev it up high (WOT) and drive it normally, the SES light will not blink or throw any code. I have also tried to reset the ECU and allow it some time to relearn the fuel trim, but after 50 miles it does not show any sign of improvement. I honestly don't think a CBE can cause this much airflow difference to create a misfiring/leaned out condition, especially when the intake is relatively stock.

I have also tried cleaning the MAFs with CRC MAF cleaners and nothing changed.

Since the car is still under OEM warranty, I will bring it to Nissan and let them diagnose the problem. I'm wondering if any guru has any further insight into this issue. Here is a picture of the Z.

[Jordo!]

the only thing that comes to mind other than bad gas is either a major exhaust leak near the secondary O2's or some sensor wire was damaged during the install.

Were you able to get any specific trouble codes?

[synolimit]

Free reving or in gear under like wot? Car won't free rev past 5k FYI.

Sounds like a misfire. As seen here post 3..."Service engine soon" light and here...Engine problem - p0300 - Whats the fix?. The cars are rich from the factory but yes they do lean out with mods. I've knocked on the dyno. Wasn't watching the light blink though. I wouldn't take it to the dealer only because you don't know if a tune was installed on the car before you bought. I'd check the plugs perhaps and while you may not be ready a tune might be in order or at least looked at with uprev.

The car was all the way hot right? Coolant and oil temp?

[synolimit]

Originally Posted by Jordo!

the only thing that comes to mind other than bad gas is either a major exhaust leak near the secondary O2's or some sensor wire was damaged during the install.

Were you able to get any specific trouble codes?

P0300 he said. You think that would do that? Guys run exhuast cut outs without issue in that spot. That's a full leak haha.

[DavidZ370]

Faulty spark plugs or wires Faulty coil (pack) Faulty oxygen sensor(s) Faulty fuel injector(s) Burned exhaust valve Faulty catalytic converter(s) Stuck/blocked/leaking EGR valve / passages Faulty camshaft position sensor Defective compute

[Wonka2581]

Why would you reset the ECU after install?? I never reset mine and never had a problem. TheECU will adjust to the new exhaust over time. I wouldnt have done that.. That might be your problem...

[thangcu35]

I'll report back what the dealer said. For now i think its from faulty plugs and coils. I notice a small exhaust leak on the right side after the 18" resonator. If it's this far downstream i wonder if it could mess up the o2 sensor somehow.

[Meulen]

I'm having a similar issue. I installed FI HFC's and CBE. It's definitely misfiring. Light withing the first 100 miles. I don't drive the car much. My mechanic ran the diagnostic and it read "multiple misfires" He cleared the code and the problem went away. I suspect there is a lot of stuff burning off in the HFC's and CBE and the O2 sensors are trying to read things for the ECU to adjust to the new exhaust. My mechanic said to let the HFC's and CBE break in a bit and see if it throws the SES light again. But it seemed fine after he cleared the SES

[thangcu35]

Originally Posted by Meulen

I'm having a similar issue. I installed FI HFC's and CBE. It's definitely misfiring. Light withing the first 100 miles. I don't drive the car much. My mechanic ran the diagnostic and it read "multiple misfires" He cleared the code and the problem went away. I suspect there is a lot of stuff burning off in the HFC's and CBE and the O2 sensors are trying to read things for the ECU to adjust to the new exhaust. My mechanic said to let the HFC's and CBE break in a bit and see if it throws the SES light again. But it seemed fine after he cleared the SES

Does your light flashes and what is the condition for that to happen in your case? Mine drives fine in the lower revs and bogs in the higher RPM under WOT. It seems to drive better when the engine is still cold, but after fully warmed up it is much more noticeable. It will blink the SES everytime I try to floor it to redline.

[Meulen]

Originally Posted by thangcu35

Does your light flashes and what is the condition for that to happen in your case? Mine drives fine in the lower revs and bogs in the higher RPM under WOT. It seems to drive better when the engine is still cold, but after fully warmed up it is much more noticeable. It will blink the SES everytime I try to floor it to redline.

No flash, and no condition really. Just normal driving. When the light was on the scanner read less airflow from on MAF sensor. But once the SES was cleared everything was perfect.

[7speed]

Originally Posted by Meulen

I'm having a similar issue. I installed FI HFC's and CBE. It's definitely misfiring. Light withing the first 100 miles. I don't drive the car much. My mechanic ran the diagnostic and it read "multiple misfires" He cleared the code and the problem went away. I suspect there is a lot of stuff burning off in the HFC's and CBE and the O2 sensors are trying to read things for the ECU to adjust to the new exhaust. My mechanic said to let the HFC's and CBE break in a bit and see if it throws the SES light again. But it seemed fine after he cleared the SES

Yeah mine flashed shortly after HFC but was fine afterwards.
Not sure what's up with flashing after cbe. Unless you other issues just check gaskets/tightness after HFC to CBE again.

[thangcu35]

Alright guys, I found and fixed the problem. I don't know why F.I. put a mini cat in the pipe before the resonator, but the matrix inside the mini cat came loose and was spiraling all the way to the 18" resonator clogging the exhaust. The reason why I did not notice this is because I bought the catback used and the seller delivered it to me in one whole piece. He told me to install it without taking it apart to reduce the chance of ruining the paper gaskets. I took his words for it and this is the result after pulling the passenger side post cat pipe out.



It took us an hour to pull all the matrix out on the passenger side. I checked the driver side mini cat and it looked intact, but to be on the safe side I gutted it with some long drill bits and lots of cursing. Two hours later..



I used the OEM metal gaskets since the paper gaskets were trashed and so far no leak. The car is noticeably louder, especially now with those mini cats gutted. Power is there and noticeably faster than when I first bought it. I finally got to enjoy driving the Z again.

[synolimit]

I'm so confused. A mini cat? FI just uses straight through resonators. Pics of the CBE?

[thangcu35]

Originally Posted by synolimit

I'm so confused. A mini cat? FI just uses straight through resonators. Pics of the CBE?

OK you got me. So what the hell do I have? It's got the same resonators and FI mufflers and tips, but the pipe before the resonator has a hump that contained catalytic matrix inside.

[Chuck33079]

That looks just like the cats in my FI system. Did you want a catted system? It would have cost extra. And on an otherwise stock car, would have cost you a bunch of power since you've still got stock cats. The seller must have had headers. And why did he tell you not to take it apart? That's kinda odd.