Hi,

2001 Jeep Cherokee Sport.

On May 18th we passed HC emissions with readings of 27 and 21 (rpms 676 and 2418). Today we failed with HC readings of 290 and 232 (rpms 923 and 2492).

We have had a recurring check engine light problem for years (small evap leak). In the June timeframe we had the oil and filter changed and the mechanic found a cracked elbow joint under the hood. To be honest it does take much longer now (perhaps 4 days rather than 1) for the check engine light to come on - but there must still be another leak.

Do you think the HC issue is related to the evap leak (even though it has been there for years) or something else ? It has probably been 2 years since I replaced the spark plugs.

Otherwise the Jeep runs great and I would have never guessed it had any issues.

Thanks

 

I've got a 2001 also and the check engine light constantly came on, but it ran great. My friend ( who works at my mechanic shop) found that he replaced all the lines & elbows starting from the evap on back.

No problems now & it's been just about a year.

 

you can try replacing plugs..

but HC is the reading of unburned gas.. ie: running rich. i would first check to see if you have any vacuum leaks in the intake system.

 

2 things. First when was your last oil change? Over time small amounts of raw gas gets past the rings and contaminated the oil. With the pcv system drawing air from the crank case it can cause higher HC levels. Second did you make sure the Catalytic convert was warm before your smog test? A cold cast does not work as well as one that has been warmed up. I always keep my car running until it's time for the test and I drive it for 15-20 minutes before taking it to be tested. The jeep I have now failed smog 6 times in 4 weeks by the previous owner who gave up and decided to sell it. I bought it drove it home looked over everything & did zero work on it. Decided to smog it for the heck of it and see where it was at since the guy did not give me any of the failed smog sheets. I warmed it up and it passed with flying colors.

Miles

 

Thought I'd follow up. Jeep passed 2nd pass through the inspection station. Mechanic replaced spark plugs, cleaned injectors, replaced air filter and replaced evaporator hose. All parts and labor came to roughly $92 USD !

In May our hydrocarbons where like 2 ppm - now they are like 15 ppm, which is ok since 100ppm passes the test. Why do you think they are not lower though ? Testing equipment ?

 

It might have something to do with colder weather. Where I live, they have winter gas and summer gas, one has more ethanol added. Maybe something like that is affecting it?