lhpdiver

Good morning.

The check engine light on our 2001 Jeep Cherokee sport, with 98k miles, has been on for years. Every now and then I disconnect the battery and the light will stay out for a few days or so. When we were in the states (now living in Mexico) I would have the codes checked and it almost always said something about one of the cylinders. Once when I had some money in my pocket I even let our very trustworthy mechanic try to resolve the issue. He put what looks like aluminum wrap around the top of the motor and the spark plugs. I guess this was to dissipate the heat better. The light still came on soon after.

I have some time on my hands and I'd like to get to the bottom of it. That and I just paid $4500 USD to import this car into Mexico and I'm holding on to it for another 10 years at least.

We live midway on a hill. If I extinguish the light (disconnect the battery), start the ignition and wait for the temperature gauge to reach the first ticky mark (maybe 3 minutes) and go DOWN the hill - the light will stay out ALL DAY. If I go UP the hill, as soon as I accelerate substantially the light comes on.

Any ideas ?

Muaddib420

Easiest way to help is to get the code read one way or another. Surely there are auto shops or mechanics in Mexico that have obd2 code scanners? If not then buy this

BAFX Products (TM) - PIC18F2480 Bluetooth OBD2 scan tool - For check engine light and other diagnostics - Android compatible
http://amzn.com/B005NLQAHS

And get an android phone and download Torque and get your code read. Anything else would be guessing.

lhpdiver

Hello again. So the code read was 456 : EVAP small leak detected. I've looked over the web and read up on some solutions requiring smoke machines etc. I doubt I'll find one of those gizmos here. My question : let's say we want to keep our Jeep another 10 years. Is there a limited amount of stuff to replace to have a new EVAP system ? Is that a crazy question ? What if we didn't want to spend lots of time and money trying to pinpoint a small leak - how much money/hoses etc make up an EVAP system on a 2001 Jeep Cherokee ?

Thanks

rackem

the easiest way to check for a small evap leak is to check the fuel cap seal. if it is damaged or weather beat replace it and start from there.

90 percent of the time that is where that code originates from (or a loose fuel cap)

lhpdiver

Guess we are in that 10%... Spent $30 USD for a new Mopar gas cap and the code still pops. I'm trying to find an alternative to taking the car to the Jeep dealership for a smoke test.

I had asked before but - how much should it cost (ballpark) to replace the rubber components that could cause that code ?

Thanks

CCKen

Do a visual inspection of the emsission tubing from ther engine bay to the fuel tank.

Often the steel tube that connects to a plastic tube on top of the fuel tank (roll-over valve) to the charcoal canister rusts through. The tube can be replaced with like item but a fuel rated 1/4" ID rubber hose can be substituted for it.

Carefully remove the rubber coupling that connects the steel tube to the plastic tube. Disconnect the rubber elbow that connects the steel tube to the canister. Unclip the tube from its supports. Remove the tube.

Connect the hose to the plastic tube. Use a constant pressure clamp to secure the hose to the tube. Secure the hose in the same places as the steel tube was using cable ties, leaving a sufficient length of hose to connect to the canister.

Remove the rubber elbow from the old steel tube. Get a coupling fitting 1/4" x 1/4". Temporarily place the rubber elbow (with coupling) in place on the canister, route the new rubber hose into proximity of the elbow/coupling and cut the rubber hose to length, then attach it to the coupling. Secure the elbow to the canister.

Over time those rubber couplings at the canister will dry rot. If yours is split you will need a new rubber elbow. If it just looks weather checked you may want to just paint the rubber coupling with a couple of coats of Liquid Tape or apply a thin coating of black RTV.

In the engine bay, you'll see plastc tubing that runs to the Duty Cycle Solenoid Valve mounted on the right side of the firewall (the gizzy that clicks all the time when the engine is running). Check the tubing along the firewall and in the area of the brake booster as the tubing takes a dip down. Sometimes this area gets crowded with cables and other tubing where they are subject to chafing. Check for a hole, or holes, chafed through a tube, or tubes. Repair with a length of vacuum hose, by cutting the damaged plastic tube and fitting the rubber hose over both ends of the tube.

If you have a Leak Detection Pump, there's a 5/8" OD plastic tube that runs from the LDP to the canister. Examine the tube its entire length, from the LDP canister for holes. There's a rubber coupling that connects the plastic tubing as it enters the top of left side of the frame rail (along with the fuel tube and other Evap tubes). Check it for being connected and/or rotted.

In general, do a complete inspection of the Evap tubing and rubber couplings (and repair as required) before spending money at a shop for a smoke test.

lhpdiver

CCKen, Thanks for the great reply. I will hand your instructions to someone here who speaks English and comes recommended.

There IS one little piece of data I should have passed along. If I fill the tank completely and make sure the gas cap is on tightly, I can drive a few days (roughly 1/8 - 1/4 of a tank) before the check engine light lights. It's done this like 3 times now. If my tank was ALWAYS full, I don't think the light would ever come on.

lhpdiver

Finally got the Jeep in for service today. It took the mechanic about 5 minutes to find a rubber elbow fitting ($17USD) near the engine area that was cracked. Will keep my fingers crossed. No smoke test needed.

I also asked the guy to do an oil lube and filter while he had it. He said - on a 2001 Cherokee there is nothing to lube. Everything is sealed. I hate to doubt the guy he has a Jeep also and certainly seemed like he knew what he was talking about. Is there nothing to lube on our Jeep ?

While I'm at it - I also had the shock absorbers replaced recently. I wanted Monroe shocks but the guy said "I strongly recommend KYB". So I said you are the expert. The roads are really bad where we live and with the new shocks I heard a rumble like noise, like a pickup with something loose in the bed. I took the Jeep back, the mechanic heard the same noise, but my original shocks back in and the noise went away. He ordered a new set of KYB shocks. It has been a couple days and once again I hear the same rumbling noises. Any Thoughts ?

Thanks

gms0623

Not sure on the shocks, however if by lube you meant to grease all of the fittings, that is something that can be done. there should be zirc fittings on most (if not all) of your steering components (tie rod ends, ball joints on the steering knuckle). Also there are fittings on your U joints and on the yoke of front drive shaft as well.