I badly need some help passing Ga smog test!
 

I have an 88 N/A 5spd, and I cannot pass the smog test to save my life! So far I've done a complete tune up, the converter is new, EGR valve works, Timing is dead on, and I only use 93 octane gas. My last readings are as follows:


readings allowed

HC 364H-376L 140H-144L

CO 2.76H-3.34L 0.89H-0.81L

NoX 501H-564L 984H-1077L

the H's are for the high speed(25mph) portion, and the L's are low speed(15mph) test. any help would be greatly appreciated, I'm baffled right now! can anyone help me!!

well....believe it or not, ur catalytic converters are probably bad..lol ur car is old, so they most likely are old and poopy inside. Check ur cats, go under ur car, and see if u can kinda smack them around lol if u here any chinging inside, or any sort of sound...like almost dirt moving around. Most likely ur cat is bad, so its not working properly, which inturn means u will not pass smog test.

the converter is 3 months old. it was hollow when i bought the car, so i replaced it.

which cat? theres one on the downpipe, which go bad pretty quickly, and then the one that would be ur cat back? if one of them was hollowed out, the 2nd one was probably hollowed out too

The NA's only have one cat and the turbos have 2 cats. Unless the car is from cali then it would have 2 cats. I think the vsv under the intake has something to do with smog. But Im not sure.

hmm now we're getting somewhere, the car probably did have 2 cats on it, the one i replaced is in the middle of the system,not directly after the manifold,see, the car came from florida, where they did away with emissions over 20 years ago so you could imagine....... i bet another cat con would help it out, because this thing runs like a champ, has tons of power (for an N/A car), and like I've said in the first post, everything checks out, timing, tune up, sensors, freakin errrrything! I've done emissions, and emission repair before, so i'm pretty familliar with how everything works. It's just that i've never really had to mess with one of these cars, this is my first supra so these tips from yous guys are awsome! I've owned rotary cars, SR20cars, I could get around those pretty easily. Too bad this engine has electronic advance........ But any how, thanks again for the tips, if anyone has more tips....keep'em flowin I certainly do appreciate them. Thanks again fellas

This car definetly came with only one converter, I'm begining to wonder if the aftermarket unit I bought is too small? I mean, it does look a little smaller than what I'm used to seeing. With the numbers I posted, is it possible that it would benefit from having another one added? I can't wait till it's 25 years old so I could swap this motor out, I know the 7m is a good motor considering the issues, but I really want a JZ block in this thing soooo bad. Thoughts anyone?

What is the timing set to? Needs to be set to 10?BTDC with the diagnostic jumper in place and NO error codes stored in the ECU.

That HC and CO is too high for just a weak cat. With the NOX so low I think you're more likely looking at an incomplete burn or too much fuel (the EGR is still a consideration if it's stuck open and cooling the chamber too much for a clean burn); Your ignition timing may be retarded (whether you're timing light agrees or not) or your exhaust cam may be advanced.

Replaced the air filter recently?

Additionally, banging on a cat only tells you if it's falling to pieces; They generally fail LONG before that happen. The catalyst gets glazed over and as such doesn't interact with the gases. Also, not that continued high HC emissions will cause this glazing and neuter your cat.

I checked the cat, definetley not falling to pieces, and thank the car gods, because its only a couple months old! I'm gonna check the base timing with the timing belt cover off and let you guys know how it goes.

Run too rich and you can kill a cat in a couple weeks.

Your HCs are way too high. I had a similar problem with my '88 and GA smog. The oxygen sensor was not functioning, but was present, so the computer never set a code.

I'd replace the oxygen sensor, but only use a Toyota factory sensor. The Botsched sensor sold at most auto parts stores are junk and don't work in Supras. It will cost a tad bit more, but will work.

Is denso is OEM for this part? same with me, no CEL on, and it does work, no codes present. it's a good thing I don't really drive it, I'd be buying another cat pretty soon! since the cat install, i've only driven it to and from the emissions station after warming it up really good.

Bosch sensors are fine, it's hard to screw up a narrow band sensor.... Now if the folks at the store are in the habit of dropping them or you think soldering dissimilar metal wires is OK, well, that's another story. Yes, I think Denso is the OEM.

Wouldn't hurt to test the AFM; The 7M-GE's VAFM is a wear component.

Thanks for helping me out guys!
 

Since the last post, it passed. I changed the O2 sensor, it just so happens that the old sensor sounded like it was broken apart inside, like a blown light bulb, and noticed that there was a hose missing from the intake tube. That combination brought the numbers down to where they needed to be. The car runs great, just need to take care of the little things. Again thank you guys for your help.

i see that you have passed.
but when was the last time your egr was cleaned???

My EGR is clean and functioning, so is the VSV. The throttle plate and intake is clean as well. I have gone through the entire emission control system, and learned quite a bit about this engine on top of what I've been learning all my life, and I like this engine. At this point, the engine is well tuned up. Next is the head stud kit, and a steel head gasket, gonna need that one of these days....