Topic: Satan built my Corollas' emissions system, and Jesus runs the DMV.

[Shenanigans]

As if I dont seriously have enough frustration with all things mechanical in my life...

I got my girlfriend a 1995 Corolla, 1.6 in the hood. The god damn thing runs like a Swiss watch and has 130,000 miles and is in perfect shape. EVERYTHING is in nice shape. It runs awesome. It came from New Mexico and the owners moved here and it sat for a couple months while they had a baby or something.

I can not for the life of me get it to pass the NOX reading. I have ran it though 8 times. Last run the HC reading is 0.19 of .80, CO was 0.11 of 12.00 but the NOX is 2.89 of 2.00. The last run I also tried running some denatured alcohol in the tank but the NOX reading got worse. The test before the NOX was 2.39. Soooo clooose ughhhh.

So far I have replaced...
 
Replaced the modulator on the EGR valve, cleaned the EGR
Vacuum switch for the EGR valve from donor car, tested to make sure it works
Thermostat
Filter and oil
Too much antifreeze, lowered to correct level
The catalytic converter that was on it was EMPTY! Put a new one on.
Has no vacuum leaks
Temp sensor.

It has new:
Radiator
plugs, plug wires, plugs gapped
Injectors
Cap of the distributor.

I have ran it though with the motor hot, even with the motor cold! The computer controls the timing etc... and its not giving me any codes. I borrowed a heat reader to make sure each side of the Cat. was the correct temperature. I seriously have no idea what to do now. What else could be causing my NOX reading?

[Hasenkopf]

did you check the egr valve operation ?   if it has one....they were put on cars to reduce nox...

[tomkimberly]

Sounds like someone placed a small ball bearing in the line to the EGR valve.


Tom

[bucky katt]

what grade gas are you running? if i understand my theory correctly, a lower octane fuel will burn faster possibly making emissions lower

[Staggerlee]

The last run I also tried running some denatured alcohol in the tank

Try isopropyl alcohol instead, it's worked for me in the past to skew the readings in my favor.

I doubt if fuel-dryer is really a hot commodity in the Phoenix area, but if you can find it in your local parts store, try dumping a couple bottles in the tank before your emissions test:

[cb750k77]

Nox Failures are very hard to diagnose...

all nox failures happen when the temp inside the combustion chamber reaches 2500deg

1. start by making sure that when you push on the diaphram on the EGR that it will make the engine stall...
2. then apply vacuum to the valve and make sure that it works...
3. make sure that the EGR is GETTING vac.. by hooking the vac line into a vac pump...

"if the above things work then you have another problem"

4. buy 3 cans of carb cleaner... take the air cleaner tube off the Throttle Body... with the car off and the engine semi warm.... have a helper stand on the throttle (wide open) and spray half a can in there and make sure everything is looking clean...
5. install the intake tube and start the car with your foot to the floor.... when the engine starts it will chug and a cloud will come out the exhaust....
6. repeat step 4 / 5 ti'll all 3 cans are gone!

7. check your timming... you are allowed + or - 2 deg... run the timming on the retarded side... (2deg less..) if my memory serves me right .... 10deg btdc you should be able to run 8... but you did mension that you might have DI so retarding the timming might be out....

8.... last resort.... water.... its tricky but you can hook up a squirt bottle to a vac line and squirt water into the plenium which someone keeps thier foot on the throttle and keeps the engine above 3.5k rpms it will require them to rev it more to keep it going cuz it will want to stall with the water and you dont want to fill the engine with water you just need enough to soften up the carbon in the intake and bake off the carbon in the cycelenders...


9... if all else fails.... you will have to pull in the intake... clean it.... and pull the head and clean the valves... and clean the combustion chamber.... just hope that you dont! and that the above tips will help you out! it has worked many times for me when i fix NoX failures... at my shop!

[Duke McDukiedook]

Get a cooler thermostat if possible, I heard that will burn more CO2 and less NOX.
 

[cb750k77]

why??? whats wrong with stock??? thermostat... do you think the factory didnt spend alot of time and money making sure the car will pass emissions??? of course they did.... i get that particular car to pass almost weekly! its a good car... he just needs to fix his 2500deg problems  i described a 9 point list he needs to follow.... please dont mutter him up with more silly wives tales about... what kind of gas he should use or some magic elixier... in a can....

i've tried all that stuff and nothing works....

the only thing that "might" work is the box of goodies from 3M

http://www.shop3m.com/60455031587.html?WT.z_xsell=1&WT.z_refSKU=60980105427

[Duke McDukiedook]

Odds are pretty good that the stock thermostat got changed a while ago, EPA demanded manufacturers use thermostats that run the engine hotter, hence higher NOX emissions to reduce CO2 emissions.

That isn't a silly wives tale, that's the truth. Run a cooler running thermostat and the NOX emissions will be less. I don't know if you can find a cooler thermostat anymore though, might be a cheap fix worth trying.

[cb750k77]

Odds are pretty good that the stock thermostat got changed a while ago, EPA demanded manufacturers use thermostats that run the engine hotter, hence higher NOX emissions to reduce CO2 emissions.

That isn't a silly wives tale, that's the truth. Run a cooler running thermostat and the NOX emissions will be less. I don't know if you can find a cooler thermostat anymore though, might be a cheap fix worth trying.

and i suppose you have.... first hand knoweledge... of a repair of this sorts???

care to share why you think that a lower temp.... thermostat.... would make such a large difference??? only time that that you might get 'SLIGHTLY" higher Nox would be if the stock thermostat stuck closed and cause some MUCH higher than normal temps but on a 95 corola it would have to be about 215F plus and rising....

90% of the nox produced... is faulty EGR/ or carbon build up in the combustion chamber causeing high temps.. 2500F and over!

[bender01]

Move to SC! This state is wide open. No inspections at all! Put a v-8 in it.

[Kframe]

I read the thread title and the first thing that comes to mind is "a ding a ding dang, a ding a long ling long"!

-K

[Shenanigans]

Thanks cb750k77! I will redo and do all that. And thanks everyone for the info, things like this I have never worked on before and are a bit foreign to me.

I put vacuum on the EGR valve (with the car running) and the motor started stumbling so I know it at least works to that point. The EGR valve pulls its vacuum from the manifold so the line is pretty short and I though it was clear but I will double check it. To be honest I am starting to think that carbon build up is a likely candidate. The car came from a state that had no emission testing. I am going out to check some stuff now and will report shortly...

[Shenanigans]

Also the computer controls the timing on this particular car.

[bucky katt]

Move to SC! This state is wide open. No inspections at all! Put a v-8 in it.

exactly! inspection? what the hell is an inspection. of course i've never seen worse looking cars on the road in my life  but it did allow me to build an 85 mustang lx with a hot 514ci crate motor and drive it daily.

[gmonkey]

No one mentioned the o2 sensor.  96 should have one.

[cb750k77]

right o2 sensor... which controls ? FUEL ?

so an o2 sensor to cause a 2500deg F combustion temp would have to be a lean motor... now according to his readings... it indicates that is AF ratio is good.

[Caaveman82]

right o2 sensor... which controls ? FUEL ?

so an o2 sensor to cause a 2500deg F combustion temp would have to be a lean motor... now according to his readings... it indicates that is AF ratio is good.

Well you could throw a washer on it to lean it out a bit more. Plus even if the mix is good doesn't mean the o2 sensor is in proper working order. Also it is not just fuel seeing as how it sniffs your emissions it will cause you to use or less fuel but at the end of the day is designed to keep your car shooting out an acceptable amount of pollutants. I used to work at an auto part store and we had a lot of o2 sensors that were crap. So like I say even though the check engine light may not be on or you think the mix is good does not mean the thing is living up to it's full potential.

[cb750k77]

right o2 sensor... which controls ? FUEL ?

so an o2 sensor to cause a 2500deg F combustion temp would have to be a lean motor... now according to his readings... it indicates that is AF ratio is good.

Well you could throw a washer on it to lean it out a bit more. Plus even if the mix is good doesn't mean the o2 sensor is in proper working order. Also it is not just fuel seeing as how it sniffs your emissions it will cause you to use or less fuel but at the end of the day is designed to keep your car shooting out an acceptable amount of pollutants. I used to work at an auto part store and we had a lot of o2 sensors that were crap. So like I say even though the check engine light may not be on or you think the mix is good does not mean the thing is living up to it's full potential.

um o2 sensor does not sniff emissions!!!!!!!!!  o2 sensors LIKE I SAID controls fuel....

remember this: Nox is created when the combustion temp reaches 2,500 deg F!!!! end of story.....

that can be caused by:
lack of EGR on a EGR motor
lean mixture
over advanced timming
too much compression (jap motor from japan that had HIGH comp from the factory)
to much compression from excessive carbon buildup
carbon build up that can cause 2,500 deg F hot spots in the cycl...

Maybe a Stuck closed thermostat! (this is very rare)


THOSE ARE THINGS THAT WOULD CAUSE HIGH NOX!

please get your information correct before spewing advice! o2sensors only read o2 levels! on a 95 Toy corrolla! end of story! it is not some magical sniffer that reads emisions... all emissions readings are assumed by the manufacture...

[Caaveman82]

That is funny you say that. The o2 sensor is after all an emissions sensor and is located in the header pipe and sometimes lower if the vehicle has 2. If you go to the parts store you will not find o2 sensors under fuel parts but under emission or exhaust parts. While it does change fuel consumption it is ultimatly designed to control emissions.

[syth82]

come on guys, obviously cb750k77 knows everything there is to know about passing emissions in a 95 corolla. lets just leave it to him and stop trying to help Shenanigans out.   

[Caaveman82]

come on guys, obviously cb750k77 knows everything there is to know about passing emissions in a 95 corolla. lets just leave it to him and stop trying to help Shenanigans out.   

Damn your right....
I wish I knew everything too. *sniff* maybe some day.

[City Boy]

Hi gang.I claim no expertise on Corolla's but lot's on other nameplate heaps.Dealing with bi-annual emission checks in Ontario has taught me to switch the oxy sensor after failing the test with great results.All test numbers showed drastic improvement.Far behind in second place were the converters.    Rock On

[cb750k77]

4Gas inspection or 5 Gas???

[Shenanigans]

Alright, I read and read to the point where I understand what everything does/is for on the EGR valve and vacuum switch and double checked it over again. It works perfectly, no leaks, plugs whatever. I am confidant that I have ruled it out completely. Off idle the whole system kicks in just as it should.

So I ran 2 bottles of carb cleaner and some water in hopes that knock off as much of the carbon as possible.

Even though the computer controls the timing there is actually a way to "reset" the timing to specifications by jumping the wires on the diagnostic port. I noticed a very very slight change when I did it.

I am going to drive it a little bit then run it in again. I hope it works...
The only bad thing is the tank has a grade higher gas than normal. I cant drain it out without driving it.

Again thanks for all the help and insight. Cars suck. Now its either that the new Cat. I got is just not efficient enough, or there is just to much carbon. 

Maricopa county is the ONLY county that emission tests here. Just to give you an idea of how ridiculous it is. I had to get all my old Honda bikes tested. INCLUDING MY TRAIL 90.