Hey guys... just curious what you think regarding a problem ive been having.
Allow me to explain the situation. I bought the car two years ago and put a new motor in. Car is a 1996 Sunfire GT, and i believe the motor to be either a 98 or 99 model. Well, got it all hooked up, and it failed the etest on NOX gases. The reading was 3000+ and the limit was only 505. So i replaced the catalytic and had the EGR valve checked along with all the vacuum hoses. Still came in (after replacing the cat) at over 3000. Ended up getting it done under the table anyhow.
Well, ive decided that i want to fix this problem because my etest is coming soon. Sure i could get it under the table again...but i dont really want to. Here is a possible indicator: my idle speed is 1100, even when warmed up. Ive already had the computer checked, and the stock numbers were all there regarding fuel flow, etc... Im wondering maybe if there is a miscommunication because of the years between the motor and the car itself? Any thoughts?
Thanks.
Josh
How long has it been since youre car has had a full tune up / plugs / wires / oil change / air filter / fuel filter, Could also have a O2 sensor acting up, As you listed U got a new Cat converter, Should be ok with a fresh tune up.
I give the car tuneups at least once a year. New plugs (no wires for the 2.4), oil changes every 5000 km, air filter once a summer. O2 sensors seem ok too.... ugh, what a pain in the ass.
Check the iac for correct operation, that could explain the higher than normal idle. For the Nox issue it is most likely that the egr system is malfunctioning but since it has been checked i'm not sure what to say. Also if you have acess to a infared thermometer check the catalytic convertor once it has warmed up, it should reach around 1600 degrees F in order to eliminate exhaust contaminants.
I would check for an intake manifold leak.
High NOx is caused by high combustion temperatures. High combustion temps come from lean mixtures(Air/fuel ratio).
Care to post all the #'s from the smog check sheet?
As requested, here are some numbers:
ASM 2525 CURB IDLE
LIMIT READING RESULT | LIMIT READING RESULT
HO ppm 66 43 PASS | 200 50 PASS
CO % 0.37 0.22 PASS | 1.00 0.94 PASS
NO ppm 505 3072 FAIL | NA NA NA
DILUTION: 12.6 VALID DILUTION: 10.8 VALID
Hopefully it posts the way i want it to.. i tried to keep everything as it was on the sheet.
I was told maybe that it was the Idle Control valve? or something like that... anyone ever hear of computers not being compatible in j-bodies? like i said, the motor is a 98 or 99, i dont know at the moment and im not sure how to read the VIN (or where it even is for that matter) on the motor. I was thinking maybe there is a communication problem with the EGR system, the car telling it to do one thing and the motor doing something else? ugh... ive had a few people look at it and no one seems to be able to figure it out. Ive been trying my best to avoid the dealership because 130$ an hour labour is not healthy for my wallet...but it may come down to that option eventually
Sunfires... eh (Tom) wrote:I would check for an intake manifold leak.
High NOx is caused by high combustion temperatures. High combustion temps come from lean mixtures(Air/fuel ratio).
Care to post all the #'s from the smog check sheet?
my thought also- any induction leak after the MAF sensor is air that the computer doesn't know about. did they also give you the O2 % on the print out ? ps... the right way to check a cat system is to compare the input(front of cat pipe temp) to the output of the cat temp. the exit temp should be higher- thats how you know if the cat has lit off and is working correctly.
