Check Engine light on

[hotdawg23]

I know this is not jeep forum but i can't find an answer to this anywhere else on the net. Hoping maybe somebody out there has had this problem and can lead me to the right solution. PLEASE.
This is a 2003 Jeep Grand Cherokee with the 6 cylinder in it.
The check engine light came on a few miles after i bought it in 2007 and i had the computer cleared by a mechanic. I drove it about 150 miles and it came on again. Don't remember the code but it said the evaporative system was faulity. I found a hose that was off a canister near the gas tank and put it back on, had the computer cleared again and drove 150 miles and u guessed it, the light came back on again.
Again i don't remember the code but the scan computer the mechanic used said it was the evaporative system.
The other problem is, the message PERFORM SERVICE comes on every time i start it. I have had the oil and filters changed every 3500 miles but nothing i do clears that message... WHAT am i doing wrong or should be doing??
Thanks for any help on this.

[bradrhale]

bad gas cap maybe.

[leolkfrm]

if it is evaperative, you can smoke it. as for the service, check the manual to find the reset procedure for after service

[waterloo88chev]

Brad's right, you'd be surprised, but it really could be a bad gas cap.

[hotrodpc]

Yep, Bad Gas Cap is likely the problem. It can be other things too, but that is the cheaper "do try first". The 2nd most common thing causing Evap code is filling your tank with the motor running. Do you ever fill your tank with the motor running? If you do, DO NOT do this anymore. Almost a sure way to throw an Evap Code. Otherwise it could be crack in a hose of the Evap system. The good news is, this code will never leave you stranded and should not affect your fuel economy although it is frustrating, and if the light is on, you do not know if you have other codes in storage. I assume this is still an OBD 2 vehicle? If so, OBD 2 scanners are not real expensive these days. $79 or so for a decent one, and the good thing about those type are they will work on many differant models of vehicles. Keep in mind, these are not the high dollar "GOOD" scanners but for basic systems these are worth the money. There are some even less expensive than that out there, but you get what you pay for in these scanners in most cases. As far as Perform Service, I am not familiar with your vehicle, but if its similar to the GM Oil life system or Toyota Maintenance Redo system, then you must reset that system after you change your oil. Are you resetting anything after you do the oil changes? All that really is, is just a minder system off your odometer to remind you of oil changes. GM system is a bit more complicated than just that, but if used properly and you understand how it operates its a good system. Some will disagree with me, but I think oil changes EVERY 3000 miles is ridiculous but that is what service centers and oil manufactures have pounded in our heads so most believe you have to do it. Thats a whole other topic though.

[leolkfrm]

the old engines need oil changes every 3000 mi cause the specs on them were so wide

[hotrodpc]

Thats what they have us believing every 3000, but that is USA. If thats so true then how come in Europe where a quart of oil was $7, now probably $10, do they say every 10,000? Now its possible their price is still the same and ours has gone up to get closer to theirs. A Chevrolet 350 is a Chevrolet 350 no matter what country it is in unless the American auto makers made tighter specs for Europe exported cars. I only say this because I worked with a guy that was from Europe and he told me this about the 10,000 miles. I have never confirmed that myself, but I see no reason for the guy to make it up. Leo's statement does make sense though. Older motor had looser tolerances, but still, oil is oil and it does not wear out. I am sure some know this, and sure some don't but motor oil never wears out. It will last forever and ever. What does happen to oil and why we have to change it, is because it gets contaminated and dirty. If there was a way to keep oil clean, you would never have to change it. Its the contamination in the oil that breaks it down. Even broke down it can still give some lubrication properties, but not as well, and the junk in the oil, you don't want scoring bearings and cylinder wall that cause premature wear. There are or were some products like Amsoil filters or Frantz filters that claim you never have to change your oil. You just change the filter and add a quart for the loss you took out with the filter. I will leave that as enough said for now. I sure do not want to discourage anyone from properly maintaining a vehcile. Keeping your oil clean is most important, wether it be with filtration or by changing it. Whatever works.

[leolkfrm]

back in the day you could buy reclaimed oil for your engine....it was refiltered! maybe they changed filters more in europe?

[hotrodpc]

yep, very true Leo. What was that brand? I am trying to recall. I think it was Ray Lube brand. They reclaimed it, cleaned it, recanned it and sold it. Notice I said Canned it. Thats funny now that I think about it. Oil was not in bottles like it is today. It was in round cylinder, lined cardboard type cans. Thats even funny to think about now. Also true about motor oils today, as with engineering and technology of the engines and tolerances have improved, also has motor oil technology. There are lots of youngsters here in the forum that may not have ever seen this or will even seen it but some of us older type if we have been around engines have seen it before. You ever opened up a motor or took off a valve cover to find sludge? I mean you can get a teaspoon and scoop it out. Its nasty black flakes of motor oil. In many or most cases back then. That would have been an engine that ran Penzoil most of its life and the person did not change their oil often enough. That was parafine based motor oils, or oil higher in parafine content. Just about the same as adding candle wax to your motor. Not good.

[leolkfrm]

it was a payless station, came in refillable glass quarts with a metal spout screwed on, and was reusable from bulk. there were other brands on the store shelves. I have some metal texaco quart cans still full!