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Discussion Starter · #1 ·
Trying to get my 84Z inspected and is having a problem with passing emissions. I have my oil changed every 3-5000 miles and a new timing belt, water pump, fuel pump, spark plugs...get the picture? I don't know why it's running so rich. We take perfect care of this thing. Has the fuel computer or catalyic converter taken a dump on me or what??

Here are some numbers if they will help...CO 8.41%, O2 0.6%, HC 546ppm and CO2 9.4%

Thanks in advance, have 7 days before I'm illegal!



Post Edited (May 23, 1:42pm)
 

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How old is the cat? Sometimes that can be an issue along with an O2 sensor. Run the codes first and see if anything pops up.

Running Rich is what a Z does most of the time
 

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Discussion Starter · #3 ·
Not very mechanically inclined here, can you explain codes briefly please. We put the original fuel computer back in. It seems to run cleaner(smelling wise) but now it doesn't seem to accelerate very smoothly. We had an 88 fuel computer an it ran nice, just rich.
 

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what are the limits for the values you have displayed.....are you overlimit on Hydrocarbon (HC) Carbon Monoxide (CO) Carbon dioxide (CO2) oxygen (O2) how was youir (NOX) nitrious oxide
 

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Looks like an O2 sensor problem. Also check the TPS and make sure it is adjusted properly. 542 HC is PRETTY high, so there is definitely a mixture problem. CO is pretty high also. I would say O2, check TPS, make sure main wiring and no vaccum leaks. And if applicable in your state, what are the NOX readings? When CO goes down, Nox goes up. So if there are multiple problems, you may fix the CO problem and then fail on NOX. And when you get it retested, tell the inspector to run at as high an RPM as possible, that will help a lot, and make sure the car is at full operating temperature. But you know, I don't know what I'm talking about, I just do these tests for a living...
 

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Shouldn't there be red flags waving at the concept of running a 88 ECU in a 84?
Weren't there electrical changes between those years, like injector impedance and the O2 sensor type/wiring?

Let's establish which ECU is compatible with the current engine electrics. Is it an 84 engine, injectors, O2 and harness or something else thrown together?
 

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Discussion Starter · #7 ·
We put the original fuel computer back in and it seems to run leaner. It just doesn't accelerate smoothly through the gears.

NOX numbers aren't applicable to NC. And I will look into when the O2 sensor was replaced, if at all.
 

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I just put G2P injector cleaner in mine the day before and ran about 1/4 tank of gas through before inspection. I also drove it around for about 20 min before inspection to get it good and hot. It just passed after failing 2 weeks before....

Mine was running too rich too.
 

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Discussion Starter · #11 ·
OK...original fuel computer didn't do the trick. My numbers are still high. Looking through my records we have never changed the O2 sensor. Were is a good place to get one? Will Pepe Boys do, should I get one through the dealership or an online place?

Thanks.
 

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Discussion Starter · #12 ·
About to go and try this again, O2 sensor was replaced. If it doesn't pass this time could my head temp sensor be bad?? Possible that my car always thinks that it's cold resulting in a rich mixture? How much of a pain in the arse is that to replace?
 
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