1997 Jeep Wrangler Vacuum leak

WOODSFIRENC525

MEMBER
1997 JEEP WRANGLER
4 CYL
4WD
MANUAL
129,000 MILES

I keep replacing the O2 sensor up front, when the code tells me. It has a new cat on exhaust and O2 sensor back there is good. Engine code also tells me it maybe a vacuum leak. Well I noticed the CCV elbow is cracked near the valve cover. Could this be the vacuum leak that keeps messing up my o2 sensors? When engine light comes on, it smells of gas in the exhaust, and hesitates some. When I change the O2 sensor. It runs good for about 800 miles. Any help would be great

1 Reply

CJ MEDEVAC

MECHANIC
11,004 POSTS

See my profile....Imma CJ Guy, however I do/ and have dealt with these Cyber-rigs from time to time that belong to family and friends.

My "mechanic Training started when I was about 10, assisting the "Big Boys" in the neighborhood with their muscle cars....Then Auto-Mechanics shop in High School.....This ended in 1982 While cars were EZ to understand.....I joined the Army and became an Airborne Ranger......All the while, I "SELF TAUGHT" myself using REPAIR MANUALS and Interrogating anyone who would clue me in....Just to keep my Jeeps and Friends and family's Rigs away from expensive shops....I STILL USE THAT TECHNIQUE...EVEN NOW.

So, I am no expert (but do know some stuff about modern rigs) and I will answer your question without writing a GIANT NOVEL.

Your rig runs on "Loops"---Open and Closed. (at this point, which is which, is irrelevent...But I'm sure another Jeep Guy Will investigate this and will know the Difference too!...then you will be on the verge of "Talking the Talk")

One Loop gives your rig "PREDETERMINED" Values, Just to make it stay running, like "Crank-up" (INEFFICIENTLY) Till all stuff (sensors) get warmed up and start sending INFO (Computer has this info in it, from factory to make it run)

The other Loop "KICKS IN" When all of your sensors come on line (such as O2 can do nothing, until it reaches a certain temp---then it gives "REAL WORLD" values to the Computer) Once the sensors give the "REAL WORLD" Values to the Computer---The computer "FIGGERS OUT" the best way to make the Engine run EFFICIENT. (very simple explanation)

Whenever ANYTHING gets messed up in a CYBER-RIG, It either TRIES TO COMPENSATE (using the other sensors to "ATTEMPT EFFICENCY"----OR----It drops back into "NON-EFFICIENT--PRESET LOOP"Just to keep you MOVING. (The Old Cars would run really awful, or not at all----You had to fix them then, or you would be walking---However it did not require MEGA TRAINING to diagnose them!)

MORAL OF THE STORY

If you have a problem on a Newer Rig...It may act like something else due to COMPUTER COMPENSATING.

Look for your vacuum leak with a UN-LIT!!! Propane torch...while you are running your engine, pass the "GAS" over the suspected leak----THE ENGINE WILL SMOOTH OUT when it sucks in the RAW PROPANE.....You can test this by letting your Intake suck it in....listen for the improvement.

FIX YOUR STUFF---FELLOW JEEP GUY---THAT YOU KNOW IS WRONG---You may get it out of the INEFFICIENT LOOP!!!! AND BE FINE!

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The Medic