I have been searching (obsessing? lol) these forums for 2 days trying to find an answer to my issue.. im really hoping someone can help me out..

I just bought my first car, a 99 z24.. it was supposedly etested and certified... but i guess thats another story...

Now im trying to get plates on it but i cant pass the emissions test.. here and the results of my first test..

gas limit reading
hc 64 58
co .35 .53
no 485 1321

now these numbers confuse me as high CO should result in low NOx, correct?

my mechanic told me its the cat.. so i replaced it... went back for a retest...

results were... HC 49 (slightly better) CO .36 (better, but still failed) NOx 1347 (it actually got worse!!!!)

I am at a loss... there are no DTC's...

now keep in mind.. i havent really checked plugs, wires or changed the oil... i do get some hesitation especially after a highway run... and i do smell fuel occasionally.. Im unsure of those numbers can be explained by that... especially since it hasnt thrown any codes..

any input would be great!!

i want to add...

I only havent checked wires and plugs because i cant find them... lol... im not a total car noob but they arent where i expect to see them... seems lots of stuff is hidden under this black plastic thing (which i assume is part of the air intake or something along those lines rather then a cover that i first suspected)

The car runs very well... idles at 600rpm, only waivers slightly once and awhile... and i know my gas tank is seeping a little bit from the seam... so that could be the fuel smell.. but idk..


like i said... i have done alot of reading on this and it seems my problems are all conflicting...

bad plugs and fuel smell mean running rich, which would lower my NOx..
running lean would explain the high NOx but should drop my CO levels to almost nothing...

just looking for a bit of help until i can take the car back in to the shop.. guy is a friend and promised it would pass after the cat, so im hoping he'll figure it out anyways... its just that the cat really set me back financially... i cant afford to replace anything else and not have it fix the problem...

plugs are under this cover:

remove the four 13mm bolts that hold it to the cam towers, unplug this plug, (circled in red)

theres sometimes a green clip that needs to be removed, which holds that plug into the ICM (what it plugs into) mine was lost long ago, so if you dont have one no worries.
then just pull the cover off. the spark plugs are under this cover. there are no plug wires with this ignition setup, there is a large white plastic piece attatched to the under side of this cover, which is the coil housing. looks like this(or something close to it):

when you take the cover off the spark plug boots may or may not come off with it. if they stick to the plugs, just pull em out, dont destroy em.
definately check the plugs, check the coils, make sure nothings burnt out. it sounds kinda weird for the car to be running good but have emissions problems, especially with a new cat.

best of luck with it. hope that helps a bit.

You need to go find the seller of this certified used car and get some satisfaction. Take a bigger stronger older person if you need to. If it was a dealer, he is most likely required to make your car pass inspection. In California even a private individual who sells a used car is liable for emission testing being satisfactory!

Find out your rights and laws for your State, sadly I'm afraid you got took!

You need a good old fashioned tune up. Plugs, boots, air filter, fuel filter, etc. Now you have a start point and go from here.

Dave

thanks for the info on the plugs.. will look into that..

as for getting screwed.. i suppose saying its my first car is a bit misleading... im 27 and 6'3".. lol... the car was certified but shouldnt have passed due to the gas tank.. so i just questioned the whole inspection.. the car is fine other then that.. had it checked out

it was the etest that wasnt valid... I had my mechanic send me to his buddy at GM yesterday, he called BS on the guy that did my etests.. said a new cat is pretty much a guaranteed pass.. and with no throw codes and all rediness monitors run.. its really the most logical answer..

have only done oil and air so far.. will check the plugs and coils once the snow lets up!! haha..

Im in Canada, selling cars "as is" is a standard practice... i would say the ad was misleading if anything but didnt give it much thought given how the car ran..

If you had a major leak in your tank you should be throwing an evap system code.

Have you actually scanned the the PCM or are you just going off the check engine light? Ive heard of guys taking the bulb out of the CEL or covering it up on the inside of the cluster.

If you had a major leak in your tank you should be throwing an evap system code.

Have you actually scanned the the PCM or are you just going off the check engine light? Ive heard of guys taking the bulb out of the CEL or covering it up on the inside of the cluster.

I would check the EGR system, Also check to make sure an OEM cat was installed, alot of times a TWC is replaced with simply an oxidation cat which does not have a Nox reduction chamber.



Buildin' n' Boostin for 08' - Alex Richards

pcm was scanned.. no codes, all monitors have run... and it was an OEM bolt on cat... going into GM for my etest on friday, really hoping it was a bad tester... weird to hope i got screwed.. lol

I have read about o2 sensors going bad without throwing a code.. so i always wonder... same with the EGR system.. no codes and car is running fine... but my test results say my car is a POS but myself and 2 dealer mechanics think there is nothing wrong with it based on the new cat and the numbers on the retest...

about the tank... its only seeping a little bit at the seam, my mechanic noticed it when doing the cat... plus i just filled it up... was told its ok for now, just keep it below 1/2 to be safe... gonna get some epoxy and patch er up until spring..

Alex Richards wrote:I would check the EGR system, Also check to make sure an OEM cat was installed, alot of times a TWC is replaced with simply an oxidation cat which does not have a Nox reduction chamber.

I would check that... sounds like that could be your problem. Although you still failed the CO2 part.

You could always go to canadian tire and pick up one of those "guaranteed to pass etest, or your money back" fuel additives. You should still try to figure out whats wrong, but atleast you could cheap your way pass the etest and get some plates.

PS: I've never used those additivies before, I've heard they work, but I've never needed them.

yeah... would love too... but the weather is craaaaaaap... no room in the garage to pull a car in right now...

My mechanic thinks it might need a PCM update thats emission specific but isnt sure if 99 2.4 fits into that problem (ex-gm mechanic).. His buddies at the local GM dealer think they ran the tests without warming up the car like they are supposed to so the cat was essentially useless... which could also mean i replaced my cat for nothing.. :\

that stuff from CT will be my next step... But im thinking what else could it possibly be? o2 or egr (even tho neither are throwing dtc's).. like i have said... car runs great, idles steady at 600rpm etc... its been stressing me out!!! lol.. will let the guys at GM run the test on friday and see what happens i guess...

passed the etest at the dealer today! hc and co were barely anything... NO went from 1347 to 483 without doing anything to the car... damn shady garages! failing people for repairs...

a tune up was advised (plugs, fuel filter) but at least she passed...

paul bateman wrote:passed the etest at the dealer today! hc and co were barely anything... NO went from 1347 to 483 without doing anything to the car... damn shady garages! failing people for repairs...

a tune up was advised (plugs, fuel filter) but at least she passed...

Hmmmmm, you ever read any of my thoughts about auto repair "professionals"??
I don't even trust them to put tires on my car!!!

My cars never darken the door of a shop except for tires and alignment and even then it is with much dread. The industry is not 100% corrupt but it is populated with inexperience. Mechanics aren't mechanics anymore. They are parts replacers and only doing so based upon pulling codes and looking up what it means. If you've got an issue that defies codes, they are up the proverbial creek without a paddle! Diagnose? Fix? Troubleshoot without electronic equipment?? Never heard of such a thing and they are incapable of it anyway!!

The idiot testing your car probably had just done it alone for the first time. Bet he went to some super trade school and got book smart though!

I could fill this forum on experiences and opinions on this, but I'll not do that. FYI, I was in this industry for a LONG time, I know of what I speak. I remember the first scope that showed you a plug firing on a TV Screen. The unit was the size of a really big professional tool box! The Beginning of the end of competence as I now see it looking back on it.
It's not ALL bad, cars today are head and shoulder better than what was made in the 50's 60's and 70's. They are more dependable and much long lasting.

Glad you found your problem.

Dave

well because of the tune up needs, he did sorta bend the rules for me to pass.. so i guess the shadiness is on both sides.. lol...

new cat on it set me back.. plus xmas.... ugh... the tune up has to wait a few weeks, but the plates are needed now! so this was a bonus for me... its a Christmas miracle!!! hehe

After the new cat was installed, did you drive around for a while to 'break in' the converter? And, as mentioned, was the cat hot during the test. In Ontario, there is a pre-condition cycle just before the actual test.

i did.. but maybe only 100km or so.. and no, the car usually sat waiting for the test.... naturally...