Gor Kikanian

Hi everyone, I kind of ran into a problem a week after installing my cats. My 06 350z now drives like a Prius and won’t rev past 4-5k RPMs. Not getting a check engine light or any codes either. I had the O2 sensor unplugged for a week until yesterday, but the problem persisted after I plugged them back in. I was thinking maybe the new cats were clogged but I’m not sure. Anyone know what it might be?

zakmartin

What kind of cats did you install?

Gor Kikanian

I installed a used pair of Fast Intentions HFC’s.

BluestreamDE

Didn't inspect the cats? It's probably damaged on the inside causing obstruction to airflow and the reason for poor performance.

zakmartin

I agree with Bluestream. Can you just go back to your old cats?

BTW: That tidbit of info (problem started after installing aftermarket used cats) would have been a good (and logical) thing to include in your problem report.

BluestreamDE

PS: Which one is it? Is it new or used HFCs?

Gor Kikanian

The new ones are the ones that I have on right now. Stock ones worked just fine. Do you guys think it they would work fine if I cleaned them?

zakmartin

If they're hindering your ride's performance the way you say they are, I'm guessing there's not much you can do to refurbish them. Buying used cats is generally a bad idea.

EDIT: I see you're from Texas. Were these from a flood damaged car?

Atreyu'z 350

There are several things you can do to test the cats:

1. Temperature test - Measures the temperature of the piping on the inlet neck of the cat as well as the exit neck of the cat. If the cat is working properly there should be a 25-100 degree difference between the two ends, with the exit neck being the hotter end. Make sure that you are at normal operating temperature for this test.

2. Vacuum rebound test - Attach a vacuum gauge to a vacuum port on the intake. You'll need a helper for this one, and you may need to temporarily remove the vacuum line to the evap system. start the car and let it idle. Your vacuum should normally be between 15 - 20. Now as you're watching the gauge have someone blip the throttle. The vacuum should increase sharply and return to baseline sharply. If it takes a little while to return to that baseline number, that's not a good sign. Now raise the rpm's to around 2,500 while looking at the gauge. If the reading takes a while to climb or drops steadily, that's also not a good sign.

3. Remove both upstream O2 sensors to see if there's a performance difference. If there is..............It's not a good sign.

travlee

iTrader: (8)

happens when you are a balla on a budget

Cux350z

iTrader: (162)

i believe he is saying new to the car/him, they were used.

Makes you wonder why the seller sold them or if they were damaged in shipping.

Careful that you don't try to just drive on them. They could get very very hot. Your fuel line runs down the passenger side not far from the cat.

tmdz

I've seen reports of people jacking up one of their O2 sensors if they use impact tools to remove the cats.

Keep in mind that you may need to drive for like an hour before the ECU will report the error codes.

Gor Kikanian

So I reinstalled the stock cats. Same problem. Code is gone for now, but I haven’t driven it too long so some may come. The car is operating exactly the same way as before. I know that the old cats that I bought were the cause because the interior was completely destroyed. Nothing I can do about them now, not gonna dwell on the crappy purchase of them either. Any ideas?

zakmartin

The damaged used cats may have destroyed your downstream O2 sensors. Do a live scan to see what kind of numbers they're putting out.

EDIT:

"Code is gone for now"

What code? I thought your car wasn't throwing a CEL. Was it a hidden PID? If so, which one?

travlee

iTrader: (8)

bust out the honeycomb in the "new" cats... boom, test pipes

CK_32

iTrader: (1)

Possibly your 12 year old cats were worn out, hardly working and now you have fresh cats that are actually effecting flow and sound output again. Like they were designed.

CK_32

iTrader: (1)

Yea OP the code will literally tell you what the problem is. Pretty important to mention that.

Gor Kikanian

My stock cats were always, and still are completely fine. The aftermarket ones I installed a week ago got ruined inside.

Gor Kikanian

I had a P0420 code after a little while. Sorry if I forgot to mention that. Once I reinstalled the old cats the code was gone. But the car still runs the same.

BluestreamDE

Check your O2 sensors