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Unread 01-03-2011, 01:51 PM   #1
tjlmbklr
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2002 WJ 
 
Join Date: Oct 2010
Location: Milwaukee, WI
Posts: 546
Wj Emissions fail, poor gas mileage and code clearing questions

I took my Jeep in a few days ago. It ended up failing. This added to the frustration of the place being closed 2 of the 3 times I went. my codes were EVAP control small & Gross leaks (P0455 & P0442). I did the best I could without the proper equipment to find any bad/cracked hoses. Everything seemed fine but what do I know. I am still not 100% sure my gas cap isn't bad, so I did the old Vaseline on the seal trick to make sure it isn't leaking. I cleared my code via battery disconnect and went back today. I only put about 10 miles at best on the Jeep. Well I failed today (sorry technically can't pass). They say "Unable to test the vehicle - following readiness monitors were not set:
Catalyst
Evaporative system
Oxygen Sensor

So what does this mean? How long must I drive it before they can test it.

My Jeep does seem to be getting poor mileage as well. The overhead read out today said my Average miles/gallon was 8.3 (Stock 4.7 V8). After putting about 15 miles on it today it did go up to 10.1 miles/gallon. Could this have anything to do with clearing the battery disconnect?

Thanks!

__________________
Bone Stock 2002 Grand Cherokee Limited
4.7L HO, Changed Stock NV247 Quadra-Drive T-case to a 242 Selec-Trac Shifter and all.
Upgraded my rims to 5 Spoke Rogue from '11 Grand Cherokee
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Unread 01-03-2011, 02:46 PM   #2
Twospeed
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2002 WJ 
 
Join Date: Apr 2010
Location: Evergreen, Colorado
Posts: 155
Fill out your Jeep info so we know what equipment you are talking about. 4.0, 4.7?
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Unread 01-03-2011, 02:48 PM   #3
Twospeed
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Posts: 155
There is a hose that goes to the EVAP canister on the left rear behind the wheel well that a lot of people on here, including me, have had crack and cause these codes as well as bad MPGs. Might check into that. As for the system not being ready, I'm not sure how many cycles it has to wait.
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Unread 01-03-2011, 03:50 PM   #4
rebuilder02
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2002 WJ 
 
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Posts: 136
Your jeep has to go thru a series of tests related to emissions and these all must be completed except for one. (2002 only allows one test to not be ready)

It can be extremely frustrating to complete these tests. It usually includes an overnight rest for a couple of the tests.

the driving tests usually involve random city driving for about 30 minutes and some constant highway driving for 30 minutes.

Here's something I got a while back:
Chrysler Drive Cycle Information
All Monitor Drive Trace
Pre-Conditioning Requirements:
- MIL must be off
- Cold start (Note: cold start temperature is undefined)
Driving Procedure
1) Warm engine up for five minutes (must reach closed loop)
2) Drive (with steady throttle) at a speed between 40 and 60 mph for 8 minutes.
3) Stop and idle for 3 minutes.
4) Drive (with steady throttle) at a speed above 20 mph for 2 minutes.
5) Turn key off, leave off for ten minutes (to run O2 sensor heater monitor).
Note: Due to the limited preconditions provided with this drive trace, NCVECS recommends using the monitor
specific drive traces for Chrysler vehicles.
Catalyst Monitor Drive Trace
Pre-Conditioning Requirements:
- MIL must be off.
- No DTCs present.
- Fuel level is between 15% and 85% full.
- ECT above 70º F.
- Engine must have run at least 90 seconds
- Engine between 1,350 & 1,900 rpm.
Driving Procedure
1) Idle vehicle for five minutes (to reach closed loop operation).
2) Drive with a steady vehicle speed between 30 and 45 mph for 2 minutes.
EGR System Monitor Drive Trace - Vacuum controlled
Pre-Conditioning Requirements:
- MIL must be off.
Driving Procedure
1) Idle vehicle for five minutes (to reach closed loop operation).
2) Drive with a steady vehicle speed between 40 & 60 mph for 8 minutes.
EGR System Monitor Drive Trace - Electronic
Pre-Conditioning Requirements:
- MIL must be off.
- MAP must be between 0-60 KPa.
- Engine speed between 500-850 rpm.
- ECT is above 180º F (90º C).
- No misfire temporary (pending) or matured fault present.
- A/C clutch, PS Switch and Cooling fans do not change state (turn off).
Driving Procedure
1) Idle vehicle for five (5) minutes (to reach closed loop operation).
2) Drive with a steady vehicle speed between 40 & 60 mph for 2 minutes.
3) Idle vehicle for three (3) minutes.
Note: This monitor evaluates EGR flow based on a change of engine roughness (idle stability).
Conditions causing un-stable idle will prevent this monitor from running.
Evaporative System Monitor Drive Trace
Trace 1: Standard Type
Pre-Conditioning Requirements:
- MIL must be off.
- No Evaporative DTCs present.
- Fuel level is between ½ and full.
(Note: monitor may still run with tank fill between 15% and 85%).
Driving Procedure
1) Idle vehicle for five minutes (to reach closed loop operation).
2) Drive with a steady vehicle speed between 30 and 45 mph for 2 minutes.
Trace 2: Leak Detection Pump
Pre-Conditioning Requirements:
- MIL must be off.
- No Evaporative DTCs present.
- Fuel level is between 30 & 85 % full.
Driving Procedure
1) Cold soak vehicle, start and idle vehicle for 4 minutes.
2) Drive in-town (stop and go) for 5 minutes, using smooth accelerations and decelerations.
3) Stop and idle vehicle for 4 minutes.
O2 Sensor Monitor Drive Trace
Pre-Conditioning Requirements:
- MIL must be off.
Driving Procedure
1) Idle vehicle for five minutes (to reach closed loop operation).
2) Drive with a steady vehicle speed above 25 mph for 2 minutes.
3) Stop and idle for 30 seconds.
4) Smoothly accelerate to a speed between 30 and 40 mph.
5) Repeat steps 3 & 4 five (5) times.
O2 Sensor Heater Monitor Drive Trace
Pre-Conditioning Requirements:
- MIL must be off.
Driving Procedure
1) Idle vehicle for five minutes (to reach closed loop operation).
2) Shut engine off and leave vehicle off for ten minutes.
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(02 Blue WJ 4x4 4.7L Laredo project 147K) (01 Blue WJ 4x4 4.0L Laredo 38K on engine/tranny... wife's) (99 Black WJ 4.0L Laredo Project 38K needs engine/tranny) (00 Red WJ 4x4 4.7L Limited project 200K) (97 Grey ZJ 4x4 5.2L Orvis project 200K) (97 White ZJ 5.2L Limited project 125K) (98 Green ZJ Limited crashed parts vehicle 195K) (97 Grey ZJ 5.2L Laredo 130K) (& with great fondness....Ole Yeller....my 89 Yellow Grand Wagoneer....dearly departed) Snellville, GA
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Unread 01-03-2011, 03:53 PM   #5
rebuilder02
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Don't be overwhelmed by the details of the driving tests. I've discovered after many many many drive tests that starting out with a warm up cycle first then doing start and stop city driving for 30 minutes and 30 minutes of highway driving usually leave only two or three left to complete. An overnight rest and another drive usually get it down to one left.
If you don't have a code reader then you need to invest in one if you will be doing your own vehicle work. Get one that can tell you readiness monitor status. That way you can focus on those items.

usually the Evap and O2 sensor heat are the last to complete.

Be careful from advice from the emissions folks or well intentioned mechanics. I've been told a lot of BS like it needs to drive 500 miles or 30 cold starts, etc.

You definitely have to get those codes fixed first or you will fail then you have to complete the readiness monitors tests(one allowed to not be ready)

Do what Twospeed said about checking hoses at the EVAP canister and pump.

As a stop-gap measure you can use some black electrical tape around the cracked hoses which are usually at the fittings. (temporary)
I've used electricians rubber tape as a more permanent repair and it's held up quite nicely. Of course new hoses are the best fix.

Also to answer your question about the overhead display mpg. Yes it resets that data when battery disconnected. It has to rebuild that data from driving. I've never learned how that data is obtained but I'm guessing it uses rpm, speed, and fuel pulse cyles to calculate mpg. It's usually accurate + or minus 2 mpg.
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(02 Blue WJ 4x4 4.7L Laredo project 147K) (01 Blue WJ 4x4 4.0L Laredo 38K on engine/tranny... wife's) (99 Black WJ 4.0L Laredo Project 38K needs engine/tranny) (00 Red WJ 4x4 4.7L Limited project 200K) (97 Grey ZJ 4x4 5.2L Orvis project 200K) (97 White ZJ 5.2L Limited project 125K) (98 Green ZJ Limited crashed parts vehicle 195K) (97 Grey ZJ 5.2L Laredo 130K) (& with great fondness....Ole Yeller....my 89 Yellow Grand Wagoneer....dearly departed) Snellville, GA
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Unread 01-03-2011, 06:40 PM   #6
straty1987
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Join Date: Aug 2008
Posts: 2,522
i have P0456 small leak on my 02, and its has been coming and going for the past few mouths. since my canister is in the rear bumper makes it a bit harder =. but since i have puled my batter 2 weeks ago and been driving it daily it has not come back on over 150 miles.

also while reading old post it turns out jeep made an updated version of the gas cap for the WJ that has helped fixed the small leaks (has worked 50/50 for WJ' owners). the dealer said that the gasket on the old one looks fine but is really bad and most of the time it has fixed peoples problems. i ordered one and at first the code did not go away but it has been over a week and no code yet. for the $17 its worth a shot before a smoke test.part number 52124512AA http://www.justforjeeps.com/factorygascap.html

can get a shop to do a smoke test were they put smoke into the tubes and look for the crack with a light. can be $60-$100 depending on the shop.

if you just disconnect the battery to loss the code will have to drive it for i think 50 miles before you can take the test.

did you not notice the light before going for inspection?
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Unread 01-03-2011, 07:13 PM   #7
rebuilder02
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Posts: 136
It's not the mileage it's whether the readiness monitors are complete.
50 miles may do the trick if it's mixed city and highway and also includes an overnight cold soak.
It's all about certain parameters being met by the drive cycles.
__________________
(02 Blue WJ 4x4 4.7L Laredo project 147K) (01 Blue WJ 4x4 4.0L Laredo 38K on engine/tranny... wife's) (99 Black WJ 4.0L Laredo Project 38K needs engine/tranny) (00 Red WJ 4x4 4.7L Limited project 200K) (97 Grey ZJ 4x4 5.2L Orvis project 200K) (97 White ZJ 5.2L Limited project 125K) (98 Green ZJ Limited crashed parts vehicle 195K) (97 Grey ZJ 5.2L Laredo 130K) (& with great fondness....Ole Yeller....my 89 Yellow Grand Wagoneer....dearly departed) Snellville, GA
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Unread 01-03-2011, 08:00 PM   #8
Twospeed
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Location: Evergreen, Colorado
Posts: 155
I pulled my battery and it was a few hundred miles before it came back but it did come back. It finally started making a sort of "thumping" sound, for lack of a better description, that you could hear when you were standing outside the vehicle. I found the hose had split up the side at the connection on the canister. I got the whole hose assembly with the vent for about $20. It resolved all of it. 7000 miles and no more codes.
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