Hey all.

I have had test pipes for about 2 years now. The entire time, I have had a SES light on, which I assumed was from my o2 sensors. Now, its time for me to get emissions and I'm looking to fix whatever it is thats setting off my SES.

I HAVE, I repeat, HAVE non-foulers installed. Also, I HAVE reset the ECU using the gas-throttle pumping method. The light goes off for about 2-3 days (maybe 100 miles?) then comes back.

I went to autozone and had the ECU checked, and it is throwing code P0420.

The 'probable causes' listed are:

- Large vacuum leak.
- Failed Bank 1 catalytic converter.
- Fuel system fault
- Ignition system fault

I highly doubt it is either of the last 2 seeing as the car runs fine. However, the mention of a vacuum leak has me wondering. When I get on the gas (and let off) I DO hear a hiss from my exhaust, but I have heard that this is fairly common with test pipes. Could this be a vacuum leak? Or are my o2 sensors bad? How would I know?

Any advice would be greatly appreciated.

Thank you.

 

dont you need to put your cats back in if you want to pass the emissions test?

 

Since it has been 2 years, I assume the OP has passed an emissions test? Or not? And I am not so sure about that code meaning 4 different things. Most codes are more specific than that although I did not take the time to look it up. The "large" vacuum leak is particularly strange - never seen that before.
D=Edit: check this thread on the same SES code, I didn't read it all:https://my350z.com/forum/vq35hr/4245...llic-hfcs.html

 

No, I have not passed emissions. It's 4 years for your first test. Also, for the first response - in Illinois all you have to do to pass emissions is have your ECU tell them that all is ok. So, if you don't set off any SES lights etc, you pass. That is my problem.

The code 0420 is specifically defined as 'catalyst system efficiency below threshold - bank 1'. The CAUSE of this inefficiency is the 4 different speculative points. It can be an o2 sensor, or it can be an exhaust leak.

Edit: I read in that other thread that some people have had success by stuffing brillo pad in the foulers. I might try this, but I first want to see what people think about it possibly being an exhaust leak seeing as non-foulers should do the job for a relatively-stock car.

 

A large vacuum leak has nothing to do with how your exhaust sounds or if your exhaust system has any leaks. A vacuum leak can be any hose going to the intake manifold which is broken or missing, or the intake manifold gaskets not sealing well. Reading that you have non-foulers to fix the CEL, note that not all non-foulers work. If you have your stock cats, just put those back in. The o2's reading is thinking your vehicle is either running too rich or lean, thus throwing the code. Unless....your o2 itself is bad

 

Reset the ECU just before going in for the test since it seems to be OK for 100 miles. That will at least get past that hurdle.

 

I don't think that will work. Here is an excerpt from the Illinois Emission Test website:

Quote:

Q. How can the Malfunction Indicator Lamp (MIL) be turned off?
A. Service technicians can manually turn off the MIL, but OBD systems are designed to automatically turn off the MIL if the conditions that caused a problem are no longer present. If the OBD system evaluates a component or system three consecutive times (with some exceptions) and no longer detects the initial problem, the MIL will turn off automatically.

As a result, drivers may see the MIL turn on and then turn off. For example, if the gas cap is not properly tightened after refueling, the OBD system can detect the vapor leak that exists from the cap not being completely tightened. If the gas cap is subsequently tightened, the MIL should be extinguished within a few days. This is not an indication of a faulty OBD system. In this example, the OBD system has properly diagnosed the problem and accordingly alerted the driver by illuminating the MIL.

If the MIL is turned off manually without correction of the underlying problem that caused the initial MIL illumination, the OBD system will reset the readiness monitors (see “What are readiness monitors?”), and begin the evaluation of the emissions control systems. If the OBD system has not completed the evaluation prior to the emissions test (see “How do readiness monitors affect the automotive repair industry?” and “How can readiness Monitors be set?”), the vehicle will be rejected for “not ready”. If the OBD system completes the evaluation and detects the problem again, the MIL will re-illuminate, and the vehicle will fail the emissions test. Therefore, simply turning off the MIL prior to the emissions test, will NOT allow the vehicle to pass.

End of Quote.

The simplest thing would be to just put the catalytic converters back on the car and correct the emission problems. The air you are polluting is the air that we all breathe. There is a reason for the emission control laws, whether you agree with them or not.

Test pipes are not to be used permanently, they are really to "test" if your catalytic converters have failed and will not allow the exhaust to pass through correctly. That kind of problem was fairly common when catalytic converters were first put on cars during the mid-1970's. Test pipes were put on cars to make certain the problem was the cat or not. If the cat was defective, the test pipes were to be removed and a new catalytic converter installed.

We should all do our part for the environment and keep our cars equipped with the catalytic converters. If I don't sound sympathetic to the original posters plight, I'm not. Just keep the car equipped so it will pass the emission test.

 

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Not going to disagree with that - I installed HFC instead of test pipes. But I have never ragged on anyone who decided to go the test pipe route either....

 

I won't disagree that I prob ought to keep the cats on for the environment, but considering I hardly drive my car (05' Z with 30K miles) and the test pipes improve my millage by about 2-4 MPG, I don't feel all that bad about it.

Anyway, back to the situation at hand.

Putting the cats back on and then taking them back off is a possibility, but I don't have a lift and dont feel safe using a jack to do it myself - so I would have to pay 2x to get them on and off (200$ about) which is, obviously, a lot more expensive than if I could get my non-foulers to work.

So, does anyone with non-foulers have any experience in potential fixes? I will probably try that brillo padding. I am also thinking about adding another non-fouler on, to try and take it even further out of the gas stream.