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Anyone got any smog check advice or tricks up their sleeve for passing? I tried to get my Mk2 past the beloved CA smog check and failed. I failed on the NOx measurements. Normally I'd suspect the EGR valve but its brand new along with the engine. The measurements were (actual/max)
----------------------------HC ------- CO ------ NOx
15 mph @1581 RPM 26/105 .02/.81 1333/1115
25 mph @2479 RPM 14/80 .01/.61 1357/945

Right now the engine is rebuilt 6M w<2000 mi, Thorley headers, 210 injectors, increased compression, all the factory intake and such installed. My only real questionable item is the factory cat. I may have cooked it last time on the dyno when I ran it pig rich (actually screwed the 02 sensor up). I'm hoping the new cat I ordered shows up this week so I can try it. I've only got to this weekend to pass it or the car will get non-opted for next year. I think all the #s are a little high so I hope the cat will drop them. I think the HC #s should be around 5ppm and COs should be 0. The raised compression should hurt the NOx reading but I still should be able to pass. Everything else on the motor runs perfectly. Anyone have any luck with that emissions pass in a can stuff? I'm getting desperate......

On the plus side I believe this is the 1st year in awhile that the passing #s haven't dropped. I remember when the passing HC#s were like 300 and 400. On the even more piss you off stuff the passing #s for a Mk2 are lower than my dads '95 1.8L 4cyl Escort commuter wagon, go figure.
 

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I had to set the timing back to 7 degrees to pass the 6m-gte on nox. The redpras 5m had similar trouble with nox. Both have hi-flo cats so I've always wondered if those aren't as efficient smog-wise as the stock type.

Phil D.
 

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Unfortunately I can't really adjust the timing, its part of the test. I'm surprised they let it go with the timing at 9 BTDC (actually set at 10). I've actually thought of putting the modded AFM back in (3 clicks looser) to try and lower it (it would raise the HCs though). I'm not to sure that my silicone jobbie can pass for stock though.
 

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Did the put your car as a Gross Poluter? if they did you will have to go to a test center only. I had this same problem in June, freakin car would pass smog. The NOx were way too high. Just be ready to show proof that your headers are leagal (the little sticker that comes with the DT headers)

BTW I also have a 6MGE with Toysport intake, DT Headers, 2.5" cat
 

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Discussion Starter #5
No, I always run my car on a pre check 1st. I already have to go to a test only place anyway, like usual.
 

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Try running low octane gas just enough for the test and lean back you AFM a couple of notches. How old is your CAT ? Worst case some guys use NAPTHA gas (campstove fuel) but be very careful with it it will eat your valves and pistons if you drive it hard with this in it. My 85 ^MGTE just passed flying colors only 10% of the limits, New cat and EGR system but ADFM was set for stock and 182CC Injectors with the FMU offline. perfomance sucked but it passed.

Good luck
 

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Silver Mk2,

High NOx can be caused by many different things... Here's a partial list:
Inoperative EGR system,
Excessively lean A/F ratio,
Malfunctioning cat,
Timing too advanced,
Faulty engine management or Oxygen sensor,
Engine deposits or mechanical defect,
Faulty cooling system.

This list of items all have one thing in common... They all lead to higher than normal combustion temps, which is the ultimate cause of high NOx readings.

Gas containing ethanol will help to lower combustion temps and lower NOx. Running your modded AFM to richen things up a bit should help as well. I'd doubt they'd notice your silicone job, just put some dirt/grime on it. Three clicks will cause your HC and CO numbers to go up, but they should still pass.

For more info on passing emissions tests, check out these websites.

http://www.smogsite.com/
http://www.castle-comply.com/Pages/articles/RSGDAN.html

Also check out http://www.autoshop101.com/ and click on the Technical Articles on the menu on the left side. Then look at the Emissions articles, about 2/3 of the way down the list.

I'll also forward you an email that Walt Jakl sent out about his car failing Cali NOx tests a few years ago. Very informative. :!:

Hope that helps you out.
 

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Did u clean the EGR tube built into the intake mani? Any
clogging of the EGR tubing will cause hi Nox. There's a
knockout on the top center of the intake mani for access.
If u do it then clean all the TB vac ports out too with solvent.

Get gas up to 10% ethanol (NOT methanol) before the test
too to lower ignition temps. toy says 10% is OK in owners manual.
I'd go to test with about a 1/4 tank of gasahol (maybe more than
10%) and fill tank right after test.

Also make sure your Ox sensor is working. See idle speed test
(really a Ox sensor check) in TSRM (FI-62 in 86)

hth
StanS
 

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When I had the 6M, Pacesetter, Intake pipe, open filter, and high flow cat I went to a "Pass or don't pay" place and they played with the timing and throtle position for hours but it finally passed. I went right home and gave it a tune up (it ran terrible on the way home!).
 

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I'm not exactly sure how this helps, but my dad's mechanic always dumps a whole load of gas line anti-freeze in (like, 3 or 4 bottles), after that and some of the usuall stuff he always passes. This is an old 70's V8 that GM slapped a bunch of wierd crap on to make it pollute less.
Keep in mind that this is Canadian AirCare, not whatever there is in Cali, but the systems are probably similar.
Also, this trick may fuck up your engine in some bizzare manner, so ask somebody other then me first. :wink:
 

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Well I think I'm screwed now. I tried again with a new exhaust and converter the results are worse now. Still failing on NOx, the numbers are closer to 2000 now. All the numbers were way up this time. I guess Magnaflow cats don't function too well as a smog device. I think I'm going to play my last card and remove the header and reinstall the factory manifold/converter/old exhaust. Everything in the engine is working fine (it should its brand new). I'm getting kind of tempted to install a pot in the glovebox inline with the temp sensor to richen it up. This is probably going to be my last try. Otherwise I guess I'm going to have to part the car or get another engine installed. I'm starting to get fed up with CA and stupid smog checks. It just stinks having to pay 300-400 bucks on smog checks for a car I drive a 1000 miles a year. I'd really like to get a pre '73 car just to get rid of them. I'm starting to worry that my Solara won't pass next year when I have to start smogging it.
 

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You may have already thougt of this but since the cat is new and they work better when hot...are you driving the car straight there or driving it a good distance to heat everything up first. When getting smogged here in NC I took my car to a place and they let it sit almost all day before they took it to the machine and it didn't pass the first time and had to do the longer test.
 

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Did u clean the EGR tube built into the intake mani? Any
clogging of the EGR tubing will cause hi Nox. There's a
knockout on the top center of the intake mani for access.
If u do it then clean all the TB vac ports out too with solvent.
I had the same problem with my Blupra the last time - HC and CO were fine but the NOx was a bit high. I had just put a new cat in for the previous test so I was pretty sure that wasn't the problem. The EGR valve was only two years old also...the fix turned out to be the above - there was all kinds of gunk inside of the intake manifold EGR plumbing. Got that cleaned out and it passed with good numbers.

HTH -- Bob

P.S. DON'T part out your car!!!! That would be a damn shame.
 

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Hey Aaron,

If you want to cruise down to vacaville, I have an almost brand new stock cat I used a while back for smog. Bought it from Kragen. It has 10k miles on it if that. It's yours if you need it. Don't trip on not passing. Just go to the dmv and pay your registration and get an extension. I do it all the time. I'vehad cars extended up to 3 months before.

Just checked under the mk2. It was welded on. I'll cut it off if you want it, you'll just have to weld on some flanges. LMK

On your high NOx problem, it sounds like a faulty EGR system to me. Theres 4 components that control vacuum to the EGR valve: the vacuum modulator, a bvsv on the thermo housing, and 2 vcv's under the intake manifold (if you have a manual tranny)...at least this is true on my 82. Start by checking if there is vacuum at the top EGR valve/diaphragm above 2500rpm. If there is vacuum, then the system which controls vacuum to the EGR is probly working. Also, check that there is always vacuum on the bottom EGR diaphragm/valve. Then let the car idle and apply vacuum to the top EGR valve...the idle should drop dramatically. If it doesn't, your passageway from the EGR to the intake manifold is clogged or the valve is faulty.

If you didn't get vacuum above 2500rpm at the top egr valve, check to make sure you get vacuum at the vacuum hose connecting to the P port on the vacuum modulator (P port goes to manifold and Q port goes to EGR). If you have vacuum there, pull the hose off the Q port on the modulator and make sure you have vacuum at that port when above 2500. If no vacuum is present, pull the hose off of the bottom of the modulator. This comes from the EGR valve. You should hear and feel plenty of exhaust gas coming from this hose at idle. If not, the pipe which that hose connects to (which comes from the EGR valve) is clogged...happens quite often. Pull the pipe off of the EGR valve (its held on by a phillips screw) and clean it out. If you had vacuum at P and exhaust is coming from the bottom hose, but you dont have vacuum at Q above 2500, then the modulator is faulty. If the modulator checks ok but you still don't have vcuum at the EGR valve, then one of the VCV's under the manifold is bad.

If you did not have vacuum at the P port on the modulator, then the BVSV on the thermo housing could be bad. Vacuum goes from the nipple on the TB (closest to front of engine) to this BVSV and then to the P port on the vacuum modulator. The BVSV is closed when coolant is cold and then opens up when coolant warms. It is black and has 3 ports. One port is parallel to the sensor body (we'll call it port #1...goes to vacuum modulator) and two ports which sit perpendicular to the sensor lengthwise. The perpendicular port furthest from the sensor body, which we'll call port #2, goes to the TB port closest to the front of the engine. The other perpendicular port on the BVSV closest to the sensor body, which we'll call port #3, goes to the TB port which sits away from the rest of the TB ports, pointing toward the exhaust. Check the BVSV. Below ~120F you should be able to blow through ports 1 and 3, and above ~140F you should be able to blow through ports 1 and 2.

Also, make sure that the port on the TB that sits closest to front of engine gets vacuum above 2500rpm...it may be clogged.

Checking the VCV's is hard to explain tho...thats if any of what I already said makes any sense.

If you come by to pick up that cat, I'll give you a hand finding the gremlins if you want.

Christian
 

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Stupid California laws. How many people there own cars but could get to work faster on a bike? Move to somewhere on the east-coast, most of us don't worry about emissions, we have all of these lovely forests and state parks to ensure we breathe cleaner air.

P.S. Our forests won't burn so often
 

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Christian;

The EGR is working perfect just like the manual says it should. The car dies right out when you open the valve and there is vacuum to it at the right RPM ranges. I've checked all that earlier in the week. I don't even believe there is any carbon even in the intake. Heck the exhaust ports barely even have any carbon in them yet. I've got no check engine codes. I've switched back the stock manifold and factory cat and exhaust to see if it helped. Still failed with a marginal improvement over the header with the same exhaust. About the only way I can think to richen the mixture up to lower the NOx level is to wire a pot inline with the temp sensor. My next choice would be to remove the head and go to a 2mm metal gasket to restore the compression close to stock.

I think I'm just going to pay the non-opt on the car and let it sit for now. I'm in way to deep to sell the car now. I just bought a house and I'm going to be swamped with doing home type stuff for awhile. I figure it'll be a good break to get away from the car awhile. I've actually been thinking about transferring the car title over to my uncle in Oregon to see if I can get away from smog checks for good.
 

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If your close to the San Ramon Valley, Valley Import Center is where I go to smog my Sup. Been going there for 18 yrs, HONEST and knowledgeble.
925-838-0991

CRC and Octane 104 both make an emissions additive that guarentee passing??

Good Luck!!
 
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