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i am sick of failing smog.

HandBuiltXJ

HandBuiltXJ

NAXJA Forum User
Location
Oceanside, CA
The 94 that I bought off of here has now failed smog 3 times on Nox.

1st run
@15=727(517max)
@25=662(539max)

Did plugs, sea foam intake cleaner, guarantee to pass, drove an entire tank.

2nd run
@15=587 fail (1929 rpm)
@25=534 pass

Cleaned intake again, checked for vacuum leaks, added octane, took all weight out of back of truck, maxed tire pressure to reduce rpms

3rd run
@15=649 fail (1580 rpm)
@25=534 pass


I believe it is safe to say the stuff I did between 2nd and third did not do shit since @25 stayed the same. And the truck polluted more at lower rpms.

Any thoughts or NAXJA friendly smog guys want to pm me.
 
how old is the cat? and what plugs did you put in it? i put colder heat range plugs in at smog time, that's the only way I can get mine to pass. the ones I use are RC9YC champions.
 
new cat time.
my van failed everything for the most part, or was very borderline. I put in a new cheapo cat from kragen and i was good to go, it's as clean as my 2005 saturn.
i was pulling my hair out trying to figure out the problem as it passed really well last year, and it still runs great. when i cut the old cat off, it sounded like a paper plate bean shaker, so i knew it was the problem.
 
how about high hydrocarbons? my xj barely passed that but was good on everything else.
 
I found that high hydrocarbons are due to either running too lean or an old cat. I battled a lean condition in my Volvo 240 wagon. It ended up being a vacuum leak that was introducing air into the intake after the MAF...causing a lean condition. Check your vacuum system, especially considering that XJ's are prone to vacuum leaks. Ugh, I hate smog.
 
Mine ran fine, but glad I do not have to smog mine. Maybe take it somewhere else, tell them that you have full-time 4wd and cannot be run on the dyno?
 
I assume you're going to a Test Only? Are you required to? Otherwise the smog shop can tell you what you need to do.
 
My 96 has to go to a test only, but it always runs pretty clean. Apparently XJs, or at least 96s were deemed gross polluters at some point?
 
My smog guy says every jeep that pulls in its like a coin toss if its gonna pass or fail. hahahaha

That said, my Bronco passes like its not even running everytime I take it in!!!!
 
My high compression stroker runs cleaner than new, but this dam engine, arg. Engine temps run a steady 210, not sure what is causing the high combustion temps producing the Nox.
 
Running lean usually causes higher temps in the cyls.
 
Johnnie Walker said:
Running lean usually causes higher temps in the cyls.
Click to expand...

This is true also. Check for any an all potential vacuum leaks. It could be running perfect and there's just one little rubber fitting letting air in downstream of the MAF.

Dirt22 said:
The smog tech didn't tell you why it's failing?

Last time I failed, the guy told me I needed a new gas cap...:dunno:
Click to expand...

They usually do that if the vehicle passes everything EXCEPT the gas cap evap test. Failing on that test is the worst since a new gas cap's like 10 bucks.
 
I own a repair shop. We could tell you what it needs. Guessing here on the internet will accomplish nothing. For less money than you would likely spend buying a part that you're only hoping will fix the problem we would tell you exactly what it needs. And save you a lot of time.

It's not really funny, but we regularly fix check engine lights for less than $200 after the customer has already spent $300-400 swapping in parts that didn't fix the problem. Take it to someone who can solve your problem for you.
 
Goatman said:
I own a repair shop. We could tell you what it needs. Guessing here on the internet will accomplish nothing. For less money than you would likely spend buying a part that you're only hoping will fix the problem we would tell you exactly what it needs. And save you a lot of time.

It's not really funny, but we regularly fix check engine lights for less than $200 after the customer has already spent $300-400 swapping in parts that didn't fix the problem. Take it to someone who can solve your problem for you.
Click to expand...


pretty much where I am at now, Is just dropping it off somewhere since I have already put $140 into smoggs not including parts.

If you weren't so dam far away..
 
You shouldn't have to pay every time, usually its pass or free retest. I also agree with goatman, best bet is take it to someone who knows xj's or just a reputable shop in general. Its way better to pay once for someone who can do it right, rather than just guessing and throwing parts at it.
 
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