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  #11  
Old 01-22-2011, 11:41 AM
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Actually the Chrysler system nows pumps up the system with air pressure, using a vacuum "operated" pump. Basically engine vacuum runs the pump that pumps air into the fuel system to check for leaks.

The system has been pressure and smoked tested by the dealer, if there was an actual leak, the pressure test would have shown it, the smoke check would have shown the exact location of the leak.

Although I agree, at this point, probably a visual inspection of every component and replacing any suspect connections should be done, a lot of rubber boots that connect part can develop dry rot and crack, possibly just enough to cause an intermittent leak.

Ideally, if the system passes a pressure test, there is no leak, so the fault should be in the equipment that is looking for a leak, i.e. the computer is erroneously seeing a leak that is NOT there. That is why they replaced the solenoid valve, it controls the pump. And the computer has no pressure sensors, it purely judges if there is a leak off how the pump reacts when it is energized, so they therefore suspect the pump's main control is faulty, the solenoid valve.

BUT, the EPA set the standard at a leak no greater than a 500 micron hole, so you very much in the territory of a leak that is impossible to find and can be intermittent, showing no leak at all sometimes and leaking at other times.

You have to think to yourself, how much raw fuel fumes are going to escape a 500 micron leak? Yet, that is what the EPA sets as the standard, and people end up going to the mechanic dozens of times trying to find the leak and can never find it, or what is wrong with the system.

BTW, the PCM has certain parameters for when it performs the test, usually the motor needs to be cold soaked, i.e. sit overnight and totally cold, the ambient air temp down near 40F, and it performs the test at first start up under those conditions, that is why the dealer wanted you to leave the vehicle overnight.

I've often suspected the pump itself being bad, after all, if it had the slightest leak, it would NOT pump as quickly and the computer would see that as a leak in the system, since it never looks for a leak in the pump. The pump is NOT part of the pressure check, its NOT part of the evap emission system, the solenoid valve opens for it to pump up pressure to check the system. I've contemplated replacing it, but at $110, I want to be sure. Right now, my Neon R/T only intermittently sets a CEL and DTC for the evap system, I clear it and it usually does NOT come back for a year or more, so I'm keeping my fingers crossed.

What fixed the evap system on my neon, at least to an acceptable level of only intermittently and rarely setting an evap DTC, going back several times and replacing all the rubber pieces in the system. When I finally got to the last couple on top of the gas tank and filler neck, did I get some better response. Those last couple did show some signs of dry rot.

BTW, if you DIY, make sure to use fuel hose, the fuel fumes are corrosive and will eat away at most rubbers.
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  #12  
Old 01-22-2011, 12:15 PM
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Quote:
Originally Posted by 06h View Post
Its ok calm down! What I said that Ford meets the standard and some of their vehicle's don't have gas caps. So yes you are correct Ford gas cap less system is a simple design and it works. So whats the problem? Why is everyone complicating the problem if its so simple for Ford to get it right without a gas cap?
What? FORD has developed the technology of the first true force field, and they are wasting it on capping their fuel systems??

Is there anyone on this board, other than 06h, that believes the Ford System is anything other than a spring loaded gas cap, that you just don't have to unscrew?

Again, you keep focusing on the gas cap, as this is the problem. Hello, the system warns the owner to check the cap first to make sure its NOT a simply mistaken securing of the gas cap. If the owner did secure the cap properly, the problem is a leak in the system or the test system itself.

Quote:
Originally Posted by 06h View Post
Are you still confused about thermostats. Yes they open and close in the summer and winter, how many times do we need to go over this?
Wow, just Wow and they often open different amounts in summer and winter, yet you claim no knows what they are talking about, they only open or close all the way. And then proceeded to claim people said things they never said in the same thread like you are doing now. Do you really think anyone on this forum does NOT know that?

Quote:
Originally Posted by 06h View Post
Well seems like someone is blaming the EPA. The EPA didn't design the system, did the EPA build the Commander? Didn't the system work fine when it left the dealership so how is this the EPA problem? Seems like alot of blaming others and the governments out to get ya by making life harder for you! The government isn't out for you and to drive you insane! Wouldn't it be Jeeps problem since they built it, oh that right Jeep does nothing wrong! Except for smoking pot and drinking on the job, needing government funding, building a unfit for human consumption vehicle and then wonder why anyone bought them (priceless)!

Unfit for human consumption, need we say anymore!
Again, just Wow, you're so myopic you don't even see that you've put words in people's mouth, while in the same paragraph you go on to do the exact same thing you falsely accuse others of doing.

You can certainly argue that you do NOT believe the EPA has set an unfair standard, that would be 100% reasonable debate. BUT, nope, instead you claim we are concocting conspiracy theories in some adhomid attack.

Yep, Jeep and Chrysler has had problems with some vehicles indicating Evap Emmissions system leaks, that dealerships, independent shops and owners often have difficulty repairing, requiring multiple attempts to fix it. BUT, so has Ford, GM, Toyota, Honda, Nissan, BMW, VW, Audi, Saab, Volvo, Hyndai and Kia. BUT, you refuse to even acknowledge that, and instead go on some canard about Ford coming up with a gimmick gas cap, seriously, who do you think you are fooling on this board?

Ummm, and systems working fine when they leave the dealer lot, but don't work as well several years later, really? you are really going to argue that only Jeep vehicles wear and break after years of use? Again, just Wow, you are out of it, just making insane grasps at straws to support your ridiculous claims after the fact.

The reason why so many evap system monitoring is so hard to repair is because the EPA set a bad standard that is too high, it results in systems that do NOT leak and do NOT contribute any meaningful extra pollution as testing as if they fail, and the fact the leaks are so small they can NOT be found after test, after test with multiple repair visits is evidence of that.

The EPA could have set a much lower standard and there would have NOT been any increase in actual pollution at all, and then perfectly good systems that are only slightly worn would NOT be failing tests and the failure be so extraordinarily subtle, that experts can NOT find the failure point and thus can NOT repair it.

It would be the inequivalent of a State setting a safety inspection law of putting your vehicle on a rolling dyno at the safety inspection, and if the vehicle makes less than spec HP for a new vehicle, it is therefore UNSAFE and must be corrected to make spec new HP. You don't think people would be having to make multiple visits to repair shops trying to correct that, wasting money rebuilding perfectly good motors that were only slightly worn, etc. Naw, that wouldn't be the State's fault for setting a ridiculously high standard that really did NOT prevent anything, it would all be the manufacturer's fault for building engines that actually wear with use.

Vehicles and their sub-systems wear with use and time, they degrade in their performance with that wear. Although performance degrades, it is often still well within an acceptable margin of effective use and performance. If you set standards for performance, you need to set realistic and effective standards, keeping wear in mind.

The fact that perfectly good systems from multiple manufacturers, that are NOT making any extra pollution, are failing tests, and the failure mode is so small and subtle it can't be found, is pretty good evidence that the standard to pass is too high.
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  #13  
Old 01-22-2011, 01:44 PM
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OK, now let me confuse the issue even more by telling you what the fellow that made my auxillary gas tank told me. I do consider Jake to be an expert. He told me that the Commander pressurizes the tank and compares the pressure to a known value for the gas level guage reading from the fuel level sensor. He told me that I might get the error code for a loose gas tank because of the additional space from the second tank. I have had an error twice. Both times they cleared right away with a disconnect of the battery ground cable. Knowing this probably does not help but it does show that the system is very complicated.
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2007 Jeep Green Limited 4.7 Flex Fuel, RR 2.5" 4 inch Superlift coils on rear, 1.5" Spacers, Bridgestone 265/70/17, K&N CAI, Flowmaster, Diamond Plate Locking Trunk, Blue Ox Baseplate w/D-rings, "Get Lost 4X4" Front Bumper, T-Max 9000 winch, "Get Lost rear tire carrier, 30 gal second gas tank.
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  #14  
Old 01-22-2011, 03:00 PM
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Quote:
Originally Posted by Motorcity View Post
The system works by cacuum, At startup the fuel tank has vacuum pulled, to ck for leaks. If the system can't be pulled down, it triggers a fault code. It could be a number of compnents. The vapor canister, one of many hoes in the sytem, the gas cap, fill tube, etc. They need to inspect some of the lines, for a possible leak, the canister for proper operation, & the purge solenoid, to name a couple of possible things.
Motorcity, my apologies, I just checked the FSM and it seems Jeep went back to the vacuum system. For years prior, Chrysler had gone with a over pressure pump system, like the Japanese and Germans; that was what I was describing. BUT, like I said before, its the same concept just different implementations.

Quote:
Originally Posted by HueyPilotVN View Post
OK, now let me confuse the issue even more by telling you what the fellow that made my auxillary gas tank told me. I do consider Jake to be an expert. He told me that the Commander pressurizes the tank and compares the pressure to a known value for the gas level guage reading from the fuel level sensor. He told me that I might get the error code for a loose gas tank because of the additional space from the second tank. I have had an error twice. Both times they cleared right away with a disconnect of the battery ground cable. Knowing this probably does not help but it does show that the system is very complicated.
Well, the PCM never reads an actual pressure from what I understand, it "infers" a pressure, but how the pressure pump reacts or in the case of a vacuum system, how the vacuum valves react. i.e. how long it takes for pressure/vacuum to bleed down and cause a change in poppet valves or the pump.

The way he said it, isn't wrong, it just wasn't the whole story. As far as comparing fuel level, I've never read that, BUT, it doesn't initiate the test unless you are at a certain range of fuel level. So, what he says makes sense, and is probably what is behind the reason why the test is NOT initiated
unless you are at a certain range of fuel in the tank. i.e. a big difference in empty volume in the tank would change the length of time for bleed down time and the reaction of poppet valves and/or pumps, that the computer sees and is timing.

This is what I found in the 2007 FSM, it references another type of system, so there may have changed the evap systems during different M/Y of Commanders.

Quote:
OPERATION

SYSTEM

1 - Intake Manifold

2 - Throttle Body

3 - Purge Solenoid

4 - Filter

5 - ESIM

6 - Vapor Canister

7 - Control Valve

8 - Fuel Tank

9 - Gas Cap

The ESIM (Evaporative System Integrity Monitor) is very similar to the NVLD. However, the design of the ESIM has been simplified and unlike the NVLD the ESIM does not require a solenoid. The ESIM mounts directly to the canister, eliminating the need for a mounting bracket. It is critical that the ESIM is mounted vertically. On vehicles where the canister is mounted on an angle, the ESIM requires an adaptor to maintain a vertical position. When the ESIM is installed vertically, the electrical connector is in the 3 o'clock position.

EXPLODED VIEW

1 - ESIM Housing

2 - Diaphragm

3 - Switch

4 - Cover

5 - Small Check Valve

6 - Large Check Valve

The ESIM assembly consists of a housing, a small weight and a large weight that serve as check valves, a diaphragm, a switch and a cover. There is one large weight and one small weight check valve in the ESIM assembly. A seal is attached at the end of each weighted check valve. The large weight check valve seals for pressure. The small weight check valve seals for vacuum. The weighted check valves are contained within the ESIM housing.

CUT AWAY OF MODULE

1 - Large Check Valve

2 - Fresh Air Inlet

3 - Diagram

4 - Small Check Valve

5 - Vapor Canister

The ESIM (Evaporative System Integrity Monitor), while physically different than the NVLD system, performs the same basic function as the NVLD does controlling evaporative emissions. The ESIM has been simplified because the solenoid used on the NVLD is not used on the ESIM.

The ESIM consists of housing, two check valves (sometimes referred to as weights), a diaphragm, a switch and a cover. The larger check valve seals for pressure and the smaller one seals for vacuum.

During refueling, pressure is built up in the evaporative system. When pressure reaches approximately .5 inches of water, the large check valve unseats and pressure vents to the fresh air filter.

Conversely, when the system cools and the resulting vacuum lifts the small check valve from its seat and allows fresh air to enter the system and relieve the vacuum condition. When a calibrated amount of vacuum is achieved in the evaporative system, the diaphragm is pulled inward, pushing on the spring and closing the contacts.

The ESIM conducts test on the evaporative system as follows: An engine off, non-intrusive test for small leaks and an engine running, intrusive test for medium/large leaks.

The ESIM weights seal the evap. system during engine off conditions. If the evap. system is sealed, it will be pulled into a vacuum, either due to the cool down from operating temperature or diurnal ambient temperature cycling. When the vacuum in the system exceeds about 1 H20, the vacuum switch closes. The switch closure sends a signal to the GPEC1. In order to pass the non-intrusive small leak test, the ESIM switch must close within a calculated amount of time and within a specified amount of key-off events.

If the ESIM switch does not close as specified, the test is considered inconclusive and the intrusive engine running test will be run during the next key-on cycle. This intrusive test will run on the next cold engine running condition.

Conditions for running the intrusive test are:

After the vehicle is started, the engine coolant temperature must be within 50F (10C) of ambient to indicate a cold start.
The fuel level must be between 12% and 88%.
The engine must be in closed loop.
Manifold vacuum must be greater than a minimum specified value.
Ambient temperature must be between 39F and 98F (4C and 37C) and the elevation level must be below 8500 feet.
The test is accomplished by the GPEC1 activating the purge solenoid to create a vacuum in the evaporative system. The GPEC1 then measures the amount of time it takes for the vacuum to dissipate. This is known as the vacuum decay method. If the switch opens quickly a large leak is recorded. If the switch opens after a predetermined amount of time, then the small leak matures. If the switch does not close, then a general evaporative failure is recorded. The purge monitor tests the integrity of the hose attached between the purge valve and throttle body/intake. The purge monitor is a two stage test and it runs only after the evaporative system passes the small leak test.

Even when all of the thresholds are met, a small leak wont be recorded until after the medium/large leak monitor has been run. This is accomplished by the GPEC1 activating the purge solenoid to create a vacuum in the evaporative system. The GPEC1 then measures the amount of time it takes for the vacuum to dissipate. This is known as the vacuum decay method. If the switch opens quickly a large leak is recorded. If the switch opens after a predetermined amount of time, then the small leak matures. If the medium/large leak test runs and the ESIM switch doesnt close, a general evaporative test is run. The purge solenoid is activated for approximately 10 seconds, increasing the amount of vacuum in the system. If the ESIM switch closes after the extended purge activation, a large leak fault is generated. If the switch doesnt close, a general evaporative system fault is generated.

The purge monitor tests the integrity of the hose attached between the purge valve and throttle body/intake. The purge monitor is a two stage test and it runs only after the evaporative system passes the small leak test.

Stage one of the purge monitor is non-intrusive. GPEC1 monitors the purge vapor ratio. If the ratio is above a calibrated specification, the monitor passes. Stage two is an intrusive test and it runs only if stage one fails. During the stage two test, the GPEC commands the purge solenoid to flow at a specified rate to force the purge vapor ratio to update. The vapor ratio is compared to a calibrated specification and if it is less than specified, a one-trip failure is recorded.

The ESIM switch stuck closed monitor checks to see if the switch is stuck closed. This is a power down test that runs at key-off; when the GPEC1 sees 0 rpms, the purge solenoid is energized for a maximum of 30 seconds, venting any vacuum trapped in the evaporative system. If the switch opens or was open before the test began, the monitor passes. If the switch doesnt open, the monitor fails. This is a two-trip MIL. The star scan tool can be used to force the ESIM switch stick closed monitor to run.

The GPEC1 also uses the ESIM to detect a loose or missing gas cap. The GPEC1 controller looks for a change in the fuel level (25% minimum) and then gas cap is loose or missing. If a medium/large leak is detected, a loose gas cap light illuminates and a pending one-trip fault code is set. On the GPEC1, this is a three-trip fault before the code matures
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  #15  
Old 01-23-2011, 03:40 PM
meegwell meegwell is offline
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original poster here. Wow, didnt mean to stir up so much dust!

For the poster that asked if I fuel with engine running or if the gas cap clicks, read the original post.

As far as the EPA and the system, I believe they both stink. I knew the EPA was of giant waste of my tax dollars long before I had this gas cap problem!


My solution will be to keep bringing it back to the dealer.

THanks all,

Meegwell
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