Emissions test results.

[Bathory]

I live in Massachusetts and recently got my Supra inspected, and had some questions for anyone that can help. I have done a good deal of searching on these forums, and maybe I can get more info by posting the result of my test.

First of all, info about the car. I have an 87, started as non turbo, but a few years back I purchased jdm GTE and swapped it in. The engine was running well after it was installed, until one night I was driving and the engine light came on, which turned out to be the AFM had appearently shit the sheets. So I bought a Lexus AFM with 550cc injectors, as well as a new walbro fuel pump. After installing these parts the car ran pretty much as it did previously, no significant difference. Other than those parts, I am using a BIC DDP, and tanabe hyper medallion (or whatever it is called) exhaust, with a test pipe in place of the cat.

As of this last winter I pulled the motor out so I could rebuild it. I finished with that a month or so ago and started driving the car once again last week. The car runs beautifully, It idles very smoothly, and drives even more smoothly. As of now I have ~500 miles on the motor. The car however seems to be squandering fuel. Since I was due for the inspection sticker I brought it to the inspection station, and did not pass haha.

The car failed for hydrocarbons, and carbon monoxide, NOx passed. Hydrocarbons registered at 8.19 grams per mile, the limit it 2 grams per mile. Carbon monoxide registered at 124.88 grams per mile, the limit is 30.0 grams per mile. NOx registered at .75 gpm, limit is 3.0 gpm. CO2 registered at 199.89 gpm, but does not have any limit.

I have talked to many people In my area that I know that are "mechanics" and they all keep telling me the same things, they think I need a new o2 sensor, and I need to have a cat put on the car. The o2 sensor is brand new as of last year from Toyota, so i do not think that is a likely problem. From what I understand about catalytic converters, it would reduce those numbers, but obvously at a detriment to the cat. This would in no way fix the underlying problem, as far as I can see, yet that is what everyone I know tries to tell me.

The high HC and CO numbers generaly mean the engine is running rich correct? Which also would account for the low NOx number (from what i have read this is what it would appear, if that is not the case please correct me)

Well anyway, im trying to get an idea as to what I should look into. My obvious assumption is that it has to do with the lex afm, injectors, and fuel pump. ALthough specificly I wouldnt have any idea. As best I can tell the car was not running this rich before the rebuild, I am basing this on my average fuel economy. Mind you my goal isnt simply to pass inspection, I couldnt care less about that, I just want the car to be running properly. Any ideas, suggestions, or any comments otherwise are all appreciated. Thanks for taking the time to read.

 

[Nick M]

Put the catalyst on.

 

[koulee]

Its called a catalytic converter for a reason: it doesn't get used up, but it can get clogged if too much unburned fuel goes through it.

You will probably need a tune too.

 

[SMP142]

i am out here in washington state. i just put the cat on for the test. come home and take it out and put the test pipe back in. worked for me so i dont see why it wouldnt work for you too. cat makes a noticable diff when its comes to those test.

 

[rumptis]

there is no way you are going to pass the test without a cat that is a given...if you want to know if its running rich look at the plugs or hook a wideband to it.

Did you drill out the J-Tube or bypass it or something?

Did you put on a Fuel Pressure Regulator after doing the Fuel Mods?

 

[Bathory]

Thanks for the replies.

First, I did not expect to pass without the cat. I do not have any cat to put on it, therefore the only reason I got it inspected at all was to buy me another 60 days with the rejection sticker.

The j-tube has been drilled out. I did not install any adjustable pressure regulator... but like i said, the car was certainly not running this rich before the engine had been rebuilt.

Plugs and wires are all brand new, and like I said, the engine is running well. I have not experienced any problems while driving whatsoever, other than excessive fuel consumption.

As far as putting a cat on it goes, I realize this would reduce emissions for sure, possibly enough to pass inspection. But, clearly it will not change how much fuel the engine is using in the first place, which is all that I am concerned with. Thanks.

 

[Doward]

I'd check the injectors, be sure none are leaking... also, the fuel pressure should be checked.

Like you said, the actual engine mechanicals shouldn't change the volume of fuel needed, unless you increased the VE of the motor.

 

[Bathory]

Thank you JetJock, I am not familiar with how to check the o2 sensor, but I will look up the procedure and post results as soon as I can.

I will also try to check the fuel pressure, if I can, to see where that stands, as Doward said. Thank you.

 

[Bathory]

Just to update this thread, I never was able to check the fuel pressure. However, after poking around I realized that the "J-tube" I installed was in fact not the one i had drilled out. I had a few of them, and I must have installed the wrong one.

Im not sure if this is a final resolution to the emissions problem as I have not bothered to get it retested yet. However it does seem that the cars gas milage is more in line with what I remember it being. I still will need to check the fuel pressure and other things, but im not sure when that will be, as I do not drive the car too often. Thanks everyone that replied to this thread.