hey guys i have a 95 xj that i tried to smog recently and got terrible numbers. it had way to many hydrocarbons ( not burning efficiently ) at idle, but at 2500 rpm it was perfect. i personally believe these people are idiots as my jeep gets 19 mpg with 33's and 3.55's...but it's not "efficient" enough.. the station i had my jeep tested at was also a repair station and the tester knew i worked on my own vehicles so was uninterested in helping me - he said the engine is more than likely dead (at 262k i'd have to disagree, my 89 has 270k and passes with flying colors) I told him to shove it and walked out.

at idle it scored 920/100 ppm (parts per million)
at 2500 rpm (actually clocked at 2300 rpm) it scored 80/150 ppm

the engine idles BEAUTIFULLY, though it has a knock to it at about 1200 rpm (goes away at higher rpm) - sounds like a lifter but i gave it a valve job and ran seafoam through it already. this problem arose a few days after the engine was ran with low oil.

when the engine idles i have no issues, if im under the hood and throttle it up to maybe 1.5k-2.5k area i can watch smoke blow out from the dipstick tube (really pisses me off as it ruins my brand new plug wires) anybody have an idea to fix this? i understand the engine is old and blowby happens with age but maybe an o-ring or something? open to suggestions

immediately after the failed test i replaced all plugs and wires and found #4 plug to be fouled, i rechecked the plugs after 100 miles and they are all burning perfectly.

the absolute hottest my engine will get is around 160... i ran it at 2500-3k rpm's for about an hour before trying to get tested a second time, and had it up to about 200, by the time i got to the smog station it had cooled down to 160 again. i swear i have the one 4.0 that just refuses to overheat

I am curious if any of you know why it would have good numbers at 2500 and terrible at idle? could this have been as simple as a fouled plug? I also failed to warm it up (i know right? didn't give it a tune up or warm it up?)
i cant afford to constantly test it so i am trying to eliminate every possibility before i retest.

thanks in advance guys

 

Assuming your CCV system is functional and not clogged, that's probably indicating your rings are worn. Cylinder pressure leaking into the crankcase and venting out the dipstick tube. A leakdown test will tell you.

A fouled plug can easily cause high HC numbers.

What temp thermostat are you running? Has it failed open?

 

I don't know jack**** about Emissions other than my straight-piped '92 with 219k miles passes with flying colors.

BUT i feel safe in saying the fowled plug may have had something to do with it. Also check all of your emissions hoses (CCV elbows on top of the valve cover) just to be safe. And throw some injector cleaner in the tank, burn that tank of fuel and run for about a week after that on clean fuel.

EDIT: I hate it when i post JUST after someone else unknowingly, and they say the same thing.

 

180 new thermo, my 89 ran at 190 with it, CCV is the exhaust recovery on top of valve cover right?

 

It recovers crankcase fumes. There are two hoses, one from the valve cover to the airbox that lets fresh air into the crankcase, and a second from the valve cover to the intake manifold. The second one has a metered orifice, it sucks fumes out and burns them. You should feel vacuum at the rear (suction) hose, and a slight vacuum at the intake hose where it connects to the airbox.
Careful of the fittings on top of the valve cover, they get brittle and break.

 

I type fast.

 

I pulled the line and it had seemingly great vacuum

Guess ill just have to flare the dipstick tube and use an o ring, thank you