Ok! I know it's one of those "not that big a deal" situations since it is as simple as unplugging the EVAP system, but there has to be a way to setup the evap purge control to work properly.
If someone knew the proper settings, it would be much simpler to punch in a few numbers than getting under the car and unplugging some hoses. More of a curiosity than anything else. Yes, I know it's not all that difficult to unplug some hoses.
The problem is, with the settings that are in the software right now, my fuel tank ends up with a LOT of vacuum, to the point of affecting the AFR's significantly. If I un-cap the fuel tank, the AFR's drop from 14.7:1 to 10.2:1, and then the car runs like crap, of course. I believe this to also be the root cause of the low load/low rpm stumble I have been experiencing.
If anyone has any input or info, that would be great. If you are going to simply tell me that it would be easier to just unplug the hose to the EVAP system, save your breath...I already know it is "EASIER" in a sense.
__________________
2004 Solar Yellow SRT-4 - AEM EMS - AMS37R Turbo Kit - Custom fuel system - JMCylinderhead/Crower S2 cams - Stock bottom end...for now, anyway!
609 WHP, 518 WTQ @ 28 PSI!
Best E.T. to date: 11.24
Best MPH to date: 129.77 MPH
For whatever reason, my EMS holds the purge solenoid open all the time. So i have all kinds of fun problems when i go fill up with fuel.
I dealt with AEM quite a bit to try and find the correct settings but they said since they dont have an srt-4 on site, they cant really do much about it.
If you search the AEM forums, they have a thread on how they fixed the problem with the Hondas, where the purge solenoid settings were all screwed up. But more people out there have a honda EMS than a dodge one.
Yeah, I actually read a little on the problems they were having with the RSX ECU's, but I never saw a solution posted up. In any event, I doubt the settings would be identical to ours.
And the problem with yours is the same as mine. Solenoid always open, causing a great deal of vacuum in the fuel tank! Sucks!
I un-capped the fuel tank, and AFR's immediately dropped to 10's. One nice thing, though, was the low load/low rpm stumble went completely away like this!
As of yet, no. I looked into the settings that the RSX guys use, and they will not work. They use completely different outputs than we do, and it's very likely that the frequencies and duty cycles will need to be different as well, since the purge solenoids are from different manufacturers.
I am just going to eliminate the vacuum source, and run a hose either atmospheric, or to my CAI for now.
honestly i dont know if you can do it with the srt.there are outputs for the nvld but i dont know if the aem can control it effectively.the srt stock ecu has memory cells for the purge solenoid that can sense pressure changes when refueling.here is some onfo though that might help
pasted from tech connect
The fuel filler cap incorporates a two-way relief valve that is closed to atmosphere during normal operating conditions. The relief valve is calibrated to open when a pressure of 17 kPa (2.5 psi) or vacuum of 2 kPa (0.6 in. Hg) occurs in the fuel tank. When the pressure or vacuum is relieved, the valve returns to the normally closed position.
All vehicles use a proportional purge solenoid. The solenoid regulates the rate of vapor flow from the EVAP canister to the throttle body. The PCM operates the solenoid.
During the cold start warm-up period and the hot start time delay, the PCM does not energize the solenoid. When de-energized, no vapors are purged.
The proportional purge solenoid operates at a frequency of 200 hz and is controlled by an engine controller circuit that senses the current being applied to the proportional purge solenoid (Proportional Purge Solenoid)and then adjusts that current to achieve the desired purge flow. The proportional purge solenoid controls the purge rate of fuel vapors from the vapor canister and fuel tank to the engine intake manifold
The Natural Vacuum Leak Detection (NVLD) system is the next generation evaporative leak detection system that will first be used on vehicles equipped with the Next Generation Controller (NGC). This new system replaces the leak detection pump as the method of evaporative system leak detection. This is to detect a leak equivalent to a 0.020" (0.5 mm) hole. This system has the capability to detect holes of this size very dependably.
The basic leak detection theory employed with NVLD is the "Gas Law". This is to say that the pressure in a sealed vessel will change if the temperature of the gas in the vessel changes. The vessel will only see this effect if it is indeed sealed. Even small leaks will allow the pressure in the vessel to come to equilibrium with the ambient pressure. In addition to the detection of very small leaks, this system has the capability of detecting medium as well as large evaporative system leaks.
A vent valve seals the canister vent during engine off conditions. If the vapor system has a leak of less than the failure threshold, the evaporative system will be pulled into a vacuum, either due to the cool down from operating temperature or diurnal ambient temperature cycling. The diurnal effect is considered one of the primary contributors to the leak determination by this diagnostic. When the vacuum in the system exceeds about 1" H2O (0.25 KPA), a vacuum switch closes. The switch closure sends a signal to the NGC. The NGC, via appropriate logic strategies (described below), utilizes the switch signal, or lack thereof, to make a determination of whether a leak is present.
The NVLD device is designed with a normally open vacuum switch, a normally closed solenoid, and a seal, which is actuated by both the solenoid and a diaphragm. The NVLD is located on the atmospheric vent side of the canister. The NVLD assembly may be mounted on top of the canister outlet, or in-line between the canister and atmospheric vent filter. The normally open vacuum switch will close with about 1" H2O (0.25 KPA) vacuum in the evaporative system. The diaphragm actuates the switch. This is above the opening point of the fuel inlet check valve in the fill tube so cap off leaks can be detected. Submerged fill systems must have recirculation lines that do not have the in-line normally closed check valve that protects the system from failed nozzle liquid ingestion, in order to detect cap off conditions.
The normally closed valve in the NVLD is intended to maintain the seal on the evaporative system during the engine off condition. If vacuum in the evaporative system exceeds 3" to 6" H2O (0.75 to 1.5 KPA), the valve will be pulled off the seat, opening the seal. This will protect the system from excessive vacuum as well as allowing sufficient purge flow in the event that the solenoid was to become inoperative.
The solenoid actuates the valve to unseal the canister vent while the engine is running. It also will be used to close the vent during the medium and large leak tests and during the purge flow check. This solenoid requires initial 1.5 amps of current to pull the valve open but after 100 ms. will be duty cycled down to an average of about 150 mA for the remainder of the drive cycle.
Another feature in the device is a diaphragm that will open the seal in the NVLD with pressure in the evaporative system. The device will "blow off" at about 0.5" H2O (0.12 KPA) pressure to permit the venting of vapors during refueling. An added benefit to this is that it will also allow the tank to "breathe" during increasing temperatures, thus limiting the pressure in the tank to this low level. This is beneficial because the induced vacuum during a subsequent declining temperature will achieve the switch closed (pass threshold) sooner than if the tank had to decay from a built up pressure.
The device itself has 3 wires: Switch sense, solenoid driver and ground. The NGC utilizes a high-side driver to energize and duty-cycle the solenoid.
The emission control principle used in the ORVR system is that the fuel flowing into the filler tube (appx. 1” I.D.) creates an aspiration effect which draws air into the fill tube (ORVR System Schematic). During refueling, the fuel tank is vented to the vapor canister to capture escaping vapors. With air flowing into the filler tube, there are no fuel vapors escaping to the atmosphere. Once the refueling vapors are captured by the canister, the vehicle's computer controlled purge system draws vapor out of the canister for the engine to burn. The vapors flow is metered by the purge solenoid so that there is no or minimal impact on driveability or tailpipe emissions.
As fuel starts to flow through the fill tube, it opens the normally closed check valve and enters the fuel tank. Vapor or air is expelled from the tank through the control valve to the vapor canister. Vapor is absorbed in the canister until vapor flow in the lines stops, either following shut-off or by having the fuel level in the tank rise high enough to close the control valve. The control valve(Refer to 14 - FUEL SYSTEM/FUEL DELIVERY/FUEL TANK - OPERATION) contains a float that rises to seal the large diameter vent path to the canister. At this point in the fueling of the vehicle, the tank pressure increases, the check valve closes (preventing tank fuel from spitting back at the operator), and fuel then rises up the filler tube to shut-off the dispensing nozzle.
If the engine is shut-off while the On-Board diagnostics test is running, low level tank pressure can be trapped in the fuel tank and fuel can not be added to the tank until the pressure is relieved. This is due to the leak detection pump closing the vapor outlet from the top of the tank and the one-way check valve not allowing the tank to vent through the fill tube to atmosphere. Therefore, when fuel is added, it will back-up in the fill tube and shut off the dispensing nozzle. The pressure can be eliminated in two ways: 1. Vehicle purge must be activated and for a long enough period to eliminate the pressure. 2. Removing the fuel cap and allowing enough time for the system to vent thru the recirulation tube.
that might help if you are persistant enough to make it work.venting the purge to an intake source will work too.most of the vapors will be rerouted through the turbo and eventually through the intake manifold so smelling the vapor will be minimized
also btw i totally forgot i need to get you a wotbox
that might help if you are persistant enough to make it work.venting the purge to an intake source will work too.most of the vapors will be rerouted through the turbo and eventually through the intake manifold so smelling the vapor will be minimized
also btw i totally forgot i need to get you a wotbox
Holy crap! You are a mad scientist! I bow to you...
And yeah, no huge rush on the wotbox at the moment, since I'm Spain, again...
I'll be here til July 31, then I'll be back at it, hitting the track up with some new goodies...can you say accelerator shaft?!?
Anyway, Thanks again for all the info, Jay! You the man! You've confirmed my choice of venting to the CAI.
You just reminded me of how much I DON'T know about this EMS stuff!
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AEM EVAP purge control settings anyone???
Linear Mode
