Well, I installed new cats on my 87 GXL. The engine was rebuilt 2 weeks ago. I have run 1 tank of super unleaded through with additive.



The car did not pass inspection. Interestingly, in the state of Texas they test for 3 gases. Hydrocarbons, carbon monoxide and NOx which I think is nitric oxide but not sure. The NOx is a new test this year. The inspector was really concerned that the car would fail the NOx but it passed that part easy. In fact the NOx was barely detectable. It did fail the hydrocarbons and CO.



Tonight I was trying to figure out what was wrong and I noticed that the shop that rebuilt the engine did not tighten (or maybe it loosened on its own) the lock nut for the crank angle sensor. The timing was off. I reset the timing and the car sounds and runs much better. My question is, could the timing being off cause a failure in the emissions testing? Everything else I have checked, with the help of the Haynes manual seems to be just fine. The timing was off so far that the car could not Idle below 1000 even with the air adjust screw closed all the way. Now the engine idles at 750 RPM, the popping noise in the exhaust is gone and the car has very good power.

the timing being that far off could do that. also check the acv. facing the passenger side is the acv dump tube, pull that off and start the engine, no air should come out under 3000-3800rpms



mike

It does have air coming out even at idle. Haynes manual says air should start flowing at 1500-2500 RPM. I've got air at 750. Does this indicate a bad ACV?



I also did the Haynes manual check of the EGR valve. I removed the vacuum hose from the EGR solenoid valve and I applied a vacuum. Tthe problem was that it would not hold a vacuum. The manual said that the engine shoudl run rough or stall. Nothing happened. I guess that is bad also.

This popping sound..its just a light sounding pop in the exhaust after a high rev? I noticed this on my car but i thought maybe a extremly leaky cat was causing it.

its called afterburn i think. its a small backfire more or less, very common.

yeah your acv isnt working right. you need to make sure the relief and switching solenoids work according to the manual. if they do make sure the vacuum lines are routed correctly, there is one in the front (theres are 3 lines there) that commonly gets swapped and the car wont pass smog. next you can take off the acv and see if it works.



the egr doesnt do any thing, but you should put something in the hose so its not a vacuum leak



mike

I have an update here but still need help. I took the car back to the shop that rebuilt the engine. They checked everything out and found quite a few vacuum leaks but no mal-functioning parts (ACV, EGR, etc...)



They fixed the vacuum leaks. I swear the car runs better than the day I bought it brand new but it still did not pass the inspection.



The first inspection it failed hydrocarbons and carbon monoxide. This time it only failed hydrocarbons. I guess it is getting better.



The rebuild only has about 120 miles on it and the inspectors seem to think that is why it is not passing. I have not been running it hard during the break in period (keeping it under 4000 RPM and such). Maybe that is why it won't pass. I haven't got a clue. I can't really go driving around town all day every day because it is out of inspection. I guess I could risk it, it can't be that bad to get a ticket for out of date inspection.



I took it to be inspected after it had been running for a while. The engine was good and hot (up to temp that is). I have run one thing of additive through the first tank of gas. Maybe it needs another at the next fill up.



Any other ideas? I was assured that the vacuum problem is fixed. It sure does run like everything is great.

by how much is it failing the hydrocarbons?



maybe it's just running too rich, check the sensors to see if they are within spec (coolant temp, intake air temp, o2...)

It failed by about 90 points on both the low speed and high speed.



I think it maybe running too rich because the inspectors keep making the comment on this. How do you change the fuel mixture to lean it out?

well it's difficult to do with only the stock equipment, but the stock equipment should run it well enough to pass the test unless you have modifications like header , porting, etc.



The ECU controls the fuel mixture for you, it uses the sensors on the engine to select which fuel maps to use, so if it's running rich it can easily be one of the temp sensors or the o2 sensor, definitely check them out.



Introducing a vacuum leak could also help it pass the test, it would help lean it out (kindof funny).

Also make sure the TPS is adjusted properly.

It is running the stock ECU. I have not chaged anything about the header. I do have a Bonez Superflo Cat system in it but I was assured that it would pass with this. Maybe they were wrong. I have passed with high flow cats before.



I had vacuumleaks fixed in between the first and second inspection. It did better after the vacuum leaks were fixed.



Are there easy ways to check the condition of the sensors you have mentioned?

well if the vacuum leaks are related to the systems to help emissions control (like a vacuum line that goes to the ACV that is needed to power some vacuum motor...) then repairing it would help. A simple vacuum leak will introduce more air into the engine than is being metered, which would usually cause a lean condition (but **** with idle air control probably)



regarding checking the sensors, yes it's easy, you just need a multimeter, digital or analog will work. The shop manual (and likely haynes) will have the valid ranges for the resistance the sensors should have.



The O2 sensor is just a voltage check.



the bonez high flow cat should be fine, just verify your split air pipe is connected, it's responsible for bringing the fresh air provided by the air pump into the cat.

Well at least I have the equipment needed. The split air pipe is connected, I know that for sure.



I will check the sensors tonight or tomorrow.



Thanks for the advice, I will let you know what happens.

Just to update on my situation and hopefully it may help others. I checked absolutely everything on this car and everything that had to do with the emissions was functioning properly. It was drving me crazy.



The only thing that was different was the Bonez Superflo Cat system but I had been assured by a number of people that it would pass inspection even with the high flow cats.



I could not figure out what was wrong so I decided to put a set of stock cats back on the car. Guess what.... it passed with flying colors. The gases that are checked were barely detectable. It seems that in Texas the Bonez Superflo cats won't pass the emissions testing.

was the bonez cat new or did you get it used from somebody?

The cats were brand new out of the box. Nice and silver and all.

wierd you should let the company you bought it from know, thats not supposed to be the case.

I am going to e-mail them right now. I still think there may be something else going on here because the shop said it passed with flying colors but I actually saw the results. It did not pass by much. But at least now I have some time to work on things and not worry about getting a ticket.



I don't know why I am so paranoid of getting a ticket. https://www.nopistons.com/forums/pub..._DIR#>/sad.png

so at this point the air control valve is working?



mike

To be honest, I am not sure right now. The shop said they fixed a bunch of stuff including replacing 2 solenoids (Relief valve and EGR solenoids). I haven't had a chance to see if the ACV was one of the things they worked on. I told them I did not think it was working correctly because it was blowing even at idle instead of just above 1500 RPM.



I am going to look into that this weekend. I will also check the EGR valve itself and the TPS. I just have to find the time.



But for the time being it is off to the paint and body shop.

cause the air injection is key to the car passing



mike

That damn ACV is pretty important to emissions. I can barely get my hands down to check it and the hose from the air pump to the ACV is so short that it is tough to take off.



Well, another weekend project.