Toyota Tacoma Forum banner

Passing smog with a gutted cat

3K views 19 replies 11 participants last post by  TRDOLMAN  
#1 ·
Is it possible? I know for a fact that I wont have a problem passing the visual, but anyone know how I will do against the sniffer?



 
#4 ·
I would have thought you would have thrown a CEL with gutted cats on an OBDII engine anyway. Mine sure did before I got the URD O2 sim.
OBDII systems are quirky. Just because you don't have a CEL doesn't necessarily mean your emissions are low. I know that's not what you want to hear but------

Dave
 
#11 ·
I do not know how it is done in Cali, but here in MD for 96 and later vehicles they just now do a plug in test. Your car just gets pulled in the bay and shut off. While one guy types in your vehicle info to the testing machine the other guy takes the gas cap off and puts it into the gas cap tester.

When the gas cap passes, the engine is started and the tester is plugged into the OBDII port and the two computers talk to each other. While this is going on, they look under the vehicle with a mirror to verify the cat is still there.

Then the tester prints out a report and tells if you pass or fail.

The OBDII system has several "monitors" that constantly conducts self tests of the different systems. If you have a good scan tool you can plug in your self and see if all the monitor tests have been completed and passed or not. If so your vehicle will pass MD emmissions.

What you do not want to do is disconnect the battery or reset the ECU before the emmissions testing. It can take a certain number of restarts or time period for the internal monitors to complete the testing cycle and this will cause you to fail the emmissions test.

As far as the cat being punched out or not, as long as the monitor for cat function clears the internal monitor test, you pass. Knowing this lead to the way our URD rear O2 sim was designed. It will allow the internal monitor tests to cycle and complete successfully.

Vehicles that are older then 96 and not OBDII will get a treadmill test with a tail pipe sniffer. What I do not know is about the 95 Tacoma. It is OBDII but I do not know if they will treadmill it or not in MD. If they do, you will need a good cat for the sniffer.

I know that private test stations do the testing in Cali, but I really don't know the process. I am sure that there are ways to pass there when you should not.

Gadget
 
#13 ·
The current one should work, but until it can be tested on a 4.0 with no cats we will not know for sure.

At first we though it was going to be not compatable since there is a cat temp reading in the scan tool. I had originally thought there was a temp sensor in the cat or in the sensor. After a little bit of checking I found that there is no sensor at all. It is a cat temp model that is programed into the ECU of what the cat temp should be at a given operating condition based on extensive OEM calibration testing.

I can tell you that with the cats in place our current verision will set a check engine light. Now if you are near our shop in Huntington Beach and happen to have your cats off and are whilling to leave your truck with us for a day or so, we can work this issue and come up with a solution. Interested??

Gadget
 
#14 ·
The current one should work, but until it can be tested on a 4.0 with no cats we will not know for sure.

At first we though it was going to be not compatable since there is a cat temp reading in the scan tool. I had originally thought there was a temp sensor in the cat or in the sensor. After a little bit of checking I found that there is no sensor at all. It is a cat temp model that is programed into the ECU of what the cat temp should be at a given operating condition based on extensive OEM calibration testing.

I can tell you that with the cats in place our current verision will set a check engine light. Now if you are near our shop in Huntington Beach and happen to have your cats off and are whilling to leave your truck with us for a day or so, we can work this issue and come up with a solution. Interested??

Gadget
Well Soon as I get my truck back I am heading up to jons to weld in my bung, remove some cats, and tune. So I don't see why me and jon couldn't head down to see if it works. Hell I could even have brian tune it
Image
just let me know. I am thinking removing the cats and getting a great tune can really unleash some power. We will just have to wait and see
 
#20 ·
Fab, read this quote from Gadget's post above:
"What you do not want to do is disconnect the battery or reset the ECU before the emissions testing. It can take a certain number of restarts or time period for the internal monitors to complete the testing cycle and this will cause you to fail the emissions test."

This statement is right on the money. After you reset the ECU, there are a series of monitors that start testing all the inputs and sensors supplying data to the ECU. These monitors run the tests in what's called "drive cycles". In order for these monitors to complete the tests a certain criteria of driving conditions (drive cycle) must take place. Sometimes it may take weeks for all the drive cycles and monitors to complete. If you take your truck to a smog test and all the monitors have not completed the tests---you fail immediately. As Gadget said, Don't reset too soon before a test or you will not pass.

Basically you need to fix what is causing the CEL. You can't get tested with a CEL light on and you can't get tested if the monitors haven't completed the tests. When the monitors complete the tests---the CEL will come back on. So in Cali at least, you need to fix what is causing the problem.

Dave