94YoTa_05CBR1K

Okay so I have failed smog twice with my 22re. First time around was before a blown head gasket. I failed by about 12 higher than the limit on HC on the 15 mph portion. everything else was within limits.

Second fail was recent which was after replacing a new head gasket, timing chain, oil water and fuel pump, fuel filter, plugs, wire, cap & rotor, and a sea foam treatment. The test results were higher than the 1st fail. Failed on the 15 and 25 mph HC portion. Therefor having un burned fuel.

I'm not sure if the cat and o2 sensors are bad but I was told if they were then it would throw a code which I'm not getting. Does a bad cat throw and o2 sensors throw a code? I was told that only the down pipe sensor will throw a code if bad and not the up pipe sensor. I was also told that any water or coolant due to the blown head gasket, through the system will cause the cat and o2 to go bad. Also timing is set to 5. Should I retard it to 0 or 3? Any help will be appreciated.

MaK92-4RnR

well... ill letcha know now. you can remove your cat and you wont throw a code. i took mine out on my 92 but left the o2 in there, and its perfectly fine. except loud. so even if the cat was bad, it wouldnt throw a code.

sb5walker

It's possible for the O2 sensor to read out of range without the computer knowing about it. But if the heater circuit burns out, OR, if the sensor is so fouled that it no longer switches between high & low volt (rich & lean signal), then the computer will throw a code 21. But the sensor will read out of range for quite a while before it gets bad enough to throw a code. Since it sounds like you have cleaned and tuned the motor well, a new direct-fit Denso sensor (amazon cheapest) and a new Magnaflow cat would probably get you past CA's tough smog test.

Since you're getting high HC, you should also investigate the possibility of a leaking injector, including cold start. Also check for an exhaust leak before or around the sensor - that allows oxy to be drawn into the exhaust stream, where it will fool the sensor into thinking the motor is running too lean. And verify the VS signal from the air meter is in spec - best way is to read the volts across VS and E2 on the ecu. See page EC1-124:
http://personal.utulsa.edu/~nathan-b...27troubles.pdf

peow130

As well as a leaking injector,
You should inspect your entire emissions system.
Any air leaks in the intake will cause a false lean, which will cause your engine to run rich.
Inspect the egr tubework, your throttlebody gasket, and check for vacuum leaks.
Make sure you have no exhaust leaks before your o2 sensor, too.

94YoTa_05CBR1K

How do I determine if an injector is leaking? I guess I will sea foam once again since it is also a good way to check for leaks in the exhaust system or is there another way? Thanks for your help.

sb5walker

For the cold start, you can pull it out of the plenum, reattach the fuel line, jump +B and FP in check connector, turn ignition on (but don't crank it) - that will pressurize the fuel lines. Look for any fuel dripping from the end.

For the other injectors, you either have to rig a pressurized fuel line, not easy, or send the things to witchhunter.com. Even if the injectors aren't leaking, if they are flowing unevenly, some cyls will run lean and others rich, which will increase the HC (the O2 sensor just works on the average of all cyls), so that's another good reason to send the injectors to witchhunter. A bonus is that it will run better and probably get a bit better gas mileage afterwards.

Seafoam is one good way to find exhaust leaks, also you can visually inspect the manifold for cracks and inspect all joints in the exhaust system looking for discolored areas (in a rich-running motor they'll be black). Or cut a 3-4 foot section of garden hose, put one end to your ear and point the other at all joints.

If you do use Seafoam, be aware the gunk it dislodges may foul the O2 sensor and cat. Could be that your earlier use of Seafoam degraded them. So if you change them, be sure to do it AFTER using Seafoam (plugs too). Also change your oil, since some Seafoam will sneak past your rings and get into the oil, and that will increase the hydrocarbons in your exhaust (as will just running rich for a while). Basically, always change oil before a smog test.

94YoTa_05CBR1K

sea foam is actually cat and sensor safe. It doesn't leave any residue on anything. Thanks though. Also I'm going to get my exhaust piping re done and hopefully the muffler shop will be able to tell me if the cat is any good. I wonder..

sb5walker

So it says. But people have seen their cats get red hot from a seafoam treatment. That's because of massive oily hydrocarbons passing through. Getting red-hot can damage a cat, and the oily hydrocarbons together with any carbon that gets cleaned out of the intake and cylinders can also gunk up the sensor.

94YoTa_05CBR1K

Okay so a friend that works on Toyota trucks told me that I need a new cat and o2 sensor and ill be good for smog. Now should I do that or just pay $250 to pass smog?

T.O'Brien

Well, if your concern is to pass smog, then yea replace the cat and sensor, or pay the $250. But the problem will still exist. I'm faced with the same problem. I passed smog last year after replacing the cat and the o2 sensor, but I'm reading more on A/F ratio's, timing, intake and exhaust flows to lower emissions (along with replacing some parts due to a CEL EGR malfunction...PM me with any help anybody please) but better economy and thus a bit more power...it's still gonna be slow, but she'll breathe better.

94YoTa_05CBR1K

As of now I think I will be replacing the cat and o2. However depending on the cost I will go from there.

94YoTa_05CBR1K

should i pay a tech $250 to pass it or invest in over 400 for a new cat and o2 sensor?

peow130

How about you drive down to schucks/oreillys and use their OBD sensor, and find the problem, instead of blindly troubleshooting it.

94YoTa_05CBR1K

There are no codes bro so why would I throw a scanner on it? Plus I can jump any codes myself without a scanner with a paper clip.

peow130

High HC is related to a few things.
False lean, causing a rich running condition.
Running rich.
ECT causing engine to run rich.
EGR allowing extra air into the intake, causing a lean condition, causing your engine to run rich.
Are you following me here?
Theres quite a few things besides O2 sensor that will cause high HC. Now, if you pull your O2 sensor and it's covered in gas and soot, and faulted out... Then you've got problems. Then you NEED to buy an o2 sensor, and even that might not fix the problems.

Now, how do you know theres no codes?
Have you checked with a scanner?

94YoTa_05CBR1K

Cool thanks bro. No codes because the check engine light isn't on plus I jumped it with a paper clip and nothing is showing up.

peow130

I don't trust the paperclip method, but like i said theres a ton of things you need to inspect.
I'd start with EGR and vacuum lines, like i said in like the 4th post.

94YoTa_05CBR1K

The paperclip method actually works because I've had 2 codes in the past show up on a OBDI scanner and used the paperclip and had the same exact codes show up. Also EGR was cleaned out after the head gasket rebuild and vacuum lines are good as I can tell.

scope103

?
What other method is there? Technically, there IS an OBD I Scanner for a Toyota truck, as there is a serial data stream. But I really doubt you've ever seen one. The scanners you can buy today (and the one down at O'Reilly's) is nothing more than a glorified paper clip. It just jumpers the correct pins and you look at the flashing light.

Even if you had a 90s vintage Toyota serial data reader, the codes aren't in the data stream. That scanner reads them the same way we do today.

peow130

The scanner also outputs them in a much easier way to read. as in, its not morse code, and its much harder to screw up.

While the method may be the same, the scanner also collects data from the various sensors wired into the truck. Which is why when you run a KOEO test, you get codes.

To say a scanner and a paper clip are the same, is just ridiculous.