After days of staring at my engine bay, replacing hoses and guaranteeing that the right inlets went to the right outlets, and ensuring that my timing was 6 degrees (with the ECM cable thing disconnected), I took my 84 to go get smogged so I can finally have it in my name.



So, my one victory was that NO passed, so I will take that. However, not only did the car backfire while being smogged, but the HC and CO levels are unbelievably high. This led me to one conclusion: excess richness in the mixture.

Excess richness can likely be traced back to one thing. Oxygen sensor is gummed up with debris, thus it thinks "oh, we must be lean, send in more fuel!", which then gives an excess richness in the mixture. So I went to the store and got a new oxygen sensor, pictured below:


I will tell you right now, that old sensor had to have been in there for centuries. A power tool wasn't even able to get it out, so by the sheer will of Newtonian physics and two wrenches, my father helped me break it free. I replaced the old AC sensor with an NTK one. They should (again, should) be functionally identical. Hoping that the NTK sensor is able to transmit fuel-air information much more effectively to the ECM now.

I checked the EGR and replaced the hoses around the solenoid and little drum thing. The drum holds vacuum (yet the vacuum drops after about seven seconds or so, which I hear is normal? If there are better test methods to guarantee functionality, I am open to hearing them). I also checked the PCV, which rattles, which typically means it also functions properly. I am unsure what else I could check before going in for a re-test, because I really want to make sure I can pass this time.

If you guys have had trouble with smog, but have found a way to pass, let me know what sort of magic you did. We may have cool 80s cars, but boy am I jealous of those OBD2-equipped automobiles during times like this...

 

You are running rich. High HC is unburned fuel. CO at that area is putting you into the low 14:1 area on AFR. NOx seems to go up high when going too lean.

I could suspect your fuel injectors leaking or spraying oddly. Is that system tunable? Could the FPR be acting up? My knowledge of Crossfuego is very limited.

 

I can double check my FSM to see if there is information about the FPR acting strangely (or how to access it, I have not had to do that yet. When I first got the car, the fuel was extremely old and it destroyed the original fuel pump. I replaced it with a 1985 pump, which I hear is a little more powerful than what 1984 had. There's a solid chance it threw the fuel system out of whack. I'll check it out.

 

Two things;

1/ How old is the fuel in the tank? On the CA smog test, my '89 failed with fuel that was >1yr old, and the tech mentioned the age thing as a potential factor. I siphoned off and filled with new fuel, and the car passed with flying colors. So that may or may not be relevant to your case; if it is, this may help some.

2/ Love your avatar photo with the guy in the F14 backseat reading the manual.

(If you are the actual ConnieK, love your work man.)

That is all.

 

1. The fuel is new. I drained out the fuel tank a few months back, and now I have been refilling with regular grade since then. The car probably wouldn't run with that old gas, it was bad.

2. Thank you for appreciating the small detail, I am a big fan of the F-14, and consider the early C4s to be the Tomcats of the road.

(Also, sadly I am not the real Connie K. His airline, Kalitta Air, operates some airplanes out of my hometown on military contract. As a kid, I would always see those planes fly over my house, and I thought the name "Kalitta" sounded so cool. Thus, I adopted it as a general username across some forums. I hope I haven't mislead many people...)

 

Another thing you may or may not want to try is replacing the coolant sensor. That can cause some funky run ability. Not the one on the passenger side, that's solely for grounding to trigger the cooling fan. The other one is what the computer sees and can wreak havoc on your sanity with our Crossfires running smoothly

 

It baffles me that California still requires this.

The politics with cars and businesses has that state falling into ocean.

 

This is why there are so many car guys in CA with out of state LLCs...pals of mine included in this too.

Random question, those those TBI heads have issues with worn throttle shaft bushings like Qjets? If so, perhaps you are also sucking in unmetered air tossing off the fuel trims.

 

This actually might be it. A similar case happened with my Celica. It billowed black smoke until I changed out the coolant sensor, then it began running like new (well, I wasn't alive in 1989, so I am assuming that's how the car ran when new...). Autozone sells the temperature sensors and even the connectors (from ACDelco too, go figure!). I know they sell the "new style" connector since the ones they used back in the day are now out of production.

Connector and Sensor Link: https://www.autozone.com/engine-mana...13-52/5558_0_0

Sensor by itself (NOT ACDELCO): https://www.autozone.com/engine-mana...109/146258_0_0
Connector by itself (NOT ACDELCO): https://www.autozone.com/cooling-hea..._0_0?rrec=true

The one downside with the ACDelco one is that I would have to wait to get it delivered. With those Duralast ones, I could go pick it up today, and they seem quite a bit cheaper and likely functionally identical. I mean, how different could ACDelco and Duralast possibly be? Both devices are transmitting coolant temperature data, it shouldn't be too different... I may live to regret saying that. Let me know what you guys think.


(moderators please understand that my response is not political in nature, it is a civil response about the emissions rules in the great state of California)
In some ways, I understand why they do it. Way back when, apparently Los Angeles used to be an unbreathable nightmare, then emissions regs roll around and now it's pretty nice out there. Even then, a smog check ensures that my car is running as efficiently as possible, instead of chugging through gas with each passing mile. My one frustration is the lack of a 25 year emission law. There are barely any cars left from before 1990, but somehow all post-1975 cars need to get emissions checked. Soon we may be getting a "by the mile" drivers tax out here to "replace" (lord knows if "replace" means "in addition to") the gas tax because we have too many EVs. I thought the goal was to go full-EV to eliminate gas? Seems counterintuitive now... who knows.

BOTTOM LINE is this. Smogging an old car is expensive, but it is part of my duties as a driver in this beautiful state. As long as the roads stay clean and pothole-free (and my future children can breathe clean air), I guess it is well worth it.

 

I just did a quick search and it seems like people in the past have had problems with worn throttle shaft bushings. Or, at least, they think the bushings have been causing problems. It is worth checking out.

What's my checklist now? Fuel pressure, coolant temp sensor, and throttle shaft bushings? I have quite the weekend of diagnosing ahead of me (thank the lord I bought an online FSM so I can scroll from the comfort of my sofa).

(And yes, so many CA drivers with the coolest cars have out-of-state LLCs. At this one car meet, I saw an offroad right-hand Supra that looked awesome. Looked behind it, "MONTANA" plate. Same with this C5 that had the thickest drag tires on it, and smelled like it got gallons per mile rather than miles per gallon. People can do some seriously insane things with cars...)

 

CTS always smart to check, it is probably a simple NTC sensor. So ohm it out cold and then hot, you should see its resistance start high when cold and taper to low resistance when hot. Easy with glass of iced water, then some boiled water. May want to verify the wiring to the ECU with a simple continuity test for its pins. I once bought an evap solenoid from Autozone for my '05 Civic in Duralast brand, it was just a reboxed Denso.



My pals with MT LLCs use them for grey market cars, not bringing out a drag vehicle on the streets. I deal with grey market MBs and BMWs from the 80s are they are a pain to register and insure here in Texas due to the VIN numbers...plus most had no smog stuff factory. They idle around 14:1 (1.5% CO) and lean cruise in the mid 15s so they have high NOx levels then. Certainly not gross polluters, but cannot pass due to how they are setup. Since they lean cruise, they actually burn less fuel than if they ran at 14.7:1 I have oft wondered fuel consumption for a given distance lean cruising versus stoich. I keep my heaps running as clean as I can.

Unrelated, I deleted my old 2009 6.4 Powerstroke. Bought new and did this at 9000 miles, it would average 7-8mpg city (CCLB 4x4 F350, stock height/stock tires) and had three regens in one tank! Deleted it, average went to 9-10.5 city plus no regens. So I had more tailpipe emissions, but I consumed far less fuel...so was I actually polluting more given the decrease in fuel usage? Freeway also went up about 1.5mpg average too.

 

where are you at in CA?? i have a tech 1a and wouldn't mind helping out for diag.


also this guy might be helpful

 

One way to check the shaft bushings is to spray carb cleaner at em while running. If they are sucking in unmetered air the rpms will change. Same thing to check for a gasket or vac line leak if you don't have a smoke machine
​​​​​​

 

Ditto here-if you're near Fontana area I have scan tools and a 4 gas bench-would be glad to help.

 

I managed to get the sensor out before sundown so I could bring it inside and test it with my dad at the dinner table. Needless to say, it is completely fried. Not only was it completely unresponsive to any hot or cold water tests, but there was no continuity between the little stub of the device (part that sticks into the coolant) and the connector (part that plugs into the ECM). This is what it looks like:



I am very likely going to Autozone tomorrow to get the new sensor and connectors that I linked above. I am keeping my fingers tightly crossed that it is a simple splice and crimp job to get it to work. We shall see...

(Also, isn't it interesting that some older cars were never built with smog regulations in mind, yet are somehow still subject to the same smog checks that every other car is? Its unfortunate because that means that eventually those cars will just be crushed because nobody will be willing to go through the hassle of registering them out-of-state.

Also also, those MPG savings that you have done seem pretty impressive, that's like an additional 10% savings! My dad has a Powerstroke truck of his own from 1990-something, which I hear he doesn't have to smog? I wonder how much MPG he gets, I will bring this conversation up to him in the morning and ask him. Sadly, right now the truck seems to be leaking diesel from somewhere, so it is out of commission. 400k+ miles and still runs strong. Seriously impressive vehicles.)


I'm located up in the North Bay Area. I feel like a diag might be useful for zeroing in on my exact issues with this vehicle.
(Also, I have seen a lot of that guy's videos, and he is one of the few 84 Corvette YouTubers out there with a good amount of content for the car! I hope he uploads again soon, it has been a short while.)


I plan on doing another engine run tomorrow after adding the new Duralast coolant temp sensor, and I will give it a shot with the carb cleaner. Randomly enough, I also have a smoke machine under my bed that has been sitting for a few years, so it may be a good time to dust it off and see what exactly the vacuum in my engine is doing.


Sadly that seems a little too far south for me. I am located in the North Bay Area. Thank you for your offer though, if I was closer I would have definitely taken you up on that!

 

ah yeah, i cant help. a bit too far up for the IE.

for smog, you"re only held to whatever your car could do at the time and thats it. sometimes this makes things actually eaiser...good luck having the tuner checker read a old ALDL car like that.

but i have a 96, and i'm only held to whatever is on the car and how it was tested at the time and thats it.

even though my cars 96 and has OBD2, its still gotta go on the dyno because some stupid class. however. because it is such an early obd2 car, clearing codes and a 5 min drive is enough to clear its systems and then take it straight to smog. mine has some assumingly opti related idle issues or something and still passed smog without a hitch. all of my numbers were waaaaay below max limits.

this was my smog sheet from the first time gettimg it smogged in 4 years from the guy i got it from.

 

Hard to tell which temperature sensor that is at that angle, since the passenger side head uses that style connector as does the one in the intake by the AC compressor, tho the one in front is a 2 wire vs single wire in passenger head. The drivers side head uses a flat blade style clip.

The passenger head controls the cooling fans, the intake goes to the ECM and controls fueling, while the drivers side head is just for the gauge cluster

 

My '89 just destroyed its entire catalytic converter complement with a rich condition caused solely by the failure of the stupid little carbon contact button in the distributor cap. There was no obvious sign that it had failed in the way the car ran and drove, though. Definitely include that in your inspections.

 

The fan and cluster sensors work fine. My fan kicks on at 225F on the gauge cluster exactly, so that I can guarantee works.

The sensor I removed, however, was the old ECM one. I replaced it this morning with the Autozone one I linked above, and it seemingly worked. Usually with half a tank of gas, my cluster indicates that I have 60mi of range. Today, I had 110 miles. I am unsure how accurate the cluster is for this information, but the old commercials said the computer processes data "16 times every operating second," so I hope it is at least ballpark!

My idle is also much smoother while the car warms up, which I am assuming is a product of the sensor sending correct information to the ECM to regulate fuel as the engine temp increases. I think this may be enough to pass the re-test ($35...), but I will go through the other items as well just to make sure.


I had no idea the distributor cap had any sort of carbon button in there. I will try and look at this tomorrow and see if it looks failed in any way. The last thing I'd want is to lose the catalytic converter.

 

Update
Alright, so I did something right. I took the car to the same smog shop today and had a little pre-test examination on the dyno before starting the official test.

The result? My HC dropped from 900-something during my first test to the 350s now, which means the engine is running MUCH more efficiently and is burning up the hydrocarbons. Downside? The goal is 148. I still have a ways to go, and I have a few ways for achieving this.

The smog tech (God bless his soul) advised me to retard timing to 0° (I was running 6° during the test today) and put some premium gasolina in the car. Then, before I go to the smog shop, get it driving nice and hard and hot in order to get it prepared for the test. He said to not let it idle before the test. Seems excessive, but whatever works, right?

So I already got the timing dialed back and will go to Costco tomorrow to put half a tank of premium (the other half has chevron regular). Do you guys have any tips to bring the emissions down that tiny bit? I feel like I am nearly there. But maybe that last sprint is the hardest…

(also, an EGR valve at Autozone is $110!? What happened to the economy… back in my day, there was a dollar menu at every restaurant !)