i have 96 bmw 328i evap solenoid that has .63 volts when key on then drops to .2 when engine running. If dme controls the voltage

what should voltage reading be when key in on position and then running?

My car has 72000 miles.
My car has a manual transmission.

Experienced mechanics share their insights in answering this question :
Most of the solenoids operate on either 12 or 5 volts. The solenoid should have power to it with the engine running, and the ECU will ground the negative terminal when it decides its time to open the valve. So the readings should be 12 v on both terminals when the engine is running and the valve is closed, and 12, 0 when the valve is commanded to open. My guess is you are trying to solve an evaporative emissions code, and they can be pretty tricky. So it you decide to bring in a professional, contact Your Mechanic to have a technician come out to your home or office to check out your BMW and let you know what it will take to solve your problem.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

A healthy purge valve is expected to have a resistance between 14 Ohms and 30 Ohms, depending on the model. If the multimeter displays a value that is higher or lower than the appropriate range, then your purge valve is faulty and needs to be changed.
Most vehicles use similar criteria for monitoring the evap system and will need 15 to 85 percent fuel level. If the fuel level is either above 85 percent or below 15 percent, the test won`t run, and you`ll likely spend hours and multiple drive cycles attempting to validate your repairs without success.
For irrigation applications, a solenoid is considered to be good if its resistance is between 20 – 60 ohms. It is best to compare resistance measurements to that of a new solenoid. Example, if a solenoid measures 44 ohms, it would be considered good because it is between 20 – 60 ohms.
On/off solenoids have higher resistance. If you measure the resistance, it is usually greater than 10 ohms. Continuous current through these solenoids is around 0.4-0.7 Amps. They are designed to handle that amount of current indefinitely.
With the key ON and the engine OFF the purge solenoid has 12 volts supplied to it.
Every solenoid valve has a nominal actuation voltage, which is usually based on common power supply voltages such as 12 VDC, 24 VDC, 110 VAC, or 220 VAC. The nominal voltage is typically printed somewhere on the valve body or coil and is the voltage required to actuate (shift) the valve.
To remove the dirt buildup inside the valve, spray the openings of the solenoid with several spurts of MAF sensor cleaner. You might see the cleaner running out of the valve dirty, so keep spraying until it comes out clean. Grease the o-rings to keep them lubricated and working smoothly.
The first sign of trouble for your canister purge valve is the check engine light. Your canister purge valve is controlled by your car`s computer, which allows it to monitor its performance. If your car`s computer detects higher or lower than expected purging from the valve, it will illuminate the check engine light.
Voltage testing

Rotate the multimeter dial and set it to measure AC (V~) or DC (V…) voltage. Note the results. If the solenoid is operating normally, the multimeter reads a voltage that matches the rated voltage of the valve; otherwise, the coil is faulty and needs to be replaced.

An EVAP leak can cause a variety of issues, including a decrease in fuel efficiency, an increase in emissions, and a decrease in engine performance. If left unchecked, an EVAP leak can also cause damage to the catalytic converter, which can be expensive to repair.
A common issue is a loose gas cap, which can cause the check engine light to come on in newer vehicles as the ECU senses a problem with the EVAP system. If you see the check engine light and haven`t filled up with fuel recently, it`s a good idea to use a code reader or take your vehicle to a shop for diagnosis.
Start the engine and idle for four minutes, then drive in stop-and-go traffic for five minutes using smooth accelerations and decelerations. Stop and idle for 4 minutes. The EVAP monitor should be complete.
Solenoid valve coils are available in a range of wattages. In Solenoid Solution`s case, the Wattmizer valves` coils range from . 65 Watts to 9 Watts with the higher wattage coils requiring more power to operate.
How Many Ohms Should A Solenoid Have? A good solenoid is expected to have between 0 and 2 Ohms when testing resistance with the use of a multimeter.
➢ Check the resistance of the EVAP canister vent solenoid. Resistance should be between 48 and 65 ohms.
Solenoid valves are control units which, when electrically energized or de-energized, either shut off or allow fluid flow. The actuator takes the form of an electromagnet. When energized, a magnetic field builds up which pulls a plunger or pivoted armature against the action of a spring.
The Power through the coil sets the max current you want to run through the coil. so Power/Voltage=Current. Voltage/Current=Resistance.
If a solenoid cycles too fast, heat will build up faster than it can be dissipated. The solenoid becomes too weak to close, so it receives a continuous high inrush current and burns out. In rare cases, a solenoid coil will burn out due to over voltage.
For example 12 volt solenoid valve with 15 watt coil will draw 1.25 amps and if connected to a battery will have a significant power drain and will need topping up according to the power usage. Amps (current consumption) = watts (power consumption of coil) divided by 12 volts.
* If you apply 24 volts to the solenoid, you risk damaging the starter motor. Recommendation: use the proper 12 volt components. You could and if you were lucky it would work BUT at 24V it wouldn`t have the pulling power of a 12V solenoid. Buy the proper one for best results.
A typical pneumatic solenoid valve of that era may have consumed 6 Watts of power and lasted 10 million cycles. Today a pneumatic valve can be operated with power consumption as low as 0.1 Watt with a life of over 200 million cycles. This is an amazing 60 times less energy with 20 times the life.
A Water Solenoid valve 12V DC coil opens and closes the valve in less than a second. It is designed for continuous operation, with a nominal power consumption of 5 watts and it draws 0.6 amps current.
The higher the wattage necessary to operate, the more heat generated. Often, a continuously operating solenoid can burn an unprotected hand. Maintenance technicians have learned this lesson the hard way. Heat generation may be acceptable in open-air applications.
The supply voltage of the solenoid valve is from 9 to 12V DC, so it can work with most sensors available on the market.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

i have 96 bmw 328i evap solenoid that has .63 volts when key on then drops to .2 when engine running. If dme controls the voltage
ANSWER : Most of the solenoids operate on either 12 or 5 volts. The solenoid should have power to it with the engine running, and the ECU will ground the negative terminal when it decides its time to open the valve. So the readings should be 12 v on both terminals when the engine is running and the valve is closed, and 12, 0 when the valve is commanded to open. My guess is you are trying to solve an evaporative emissions code, and they can be pretty tricky. So it you decide to bring in a professional, contact Your Mechanic to have a technician come out to your home or office to check out your BMW and let you know what it will take to solve your problem.

I have a 96 Ford ranger with cel p0340 I have recently done a timing belt, engine runs great replaced cmp sensor cel still on
ANSWER : Hi There,
This may happen for a couple of reasons. First, check to be sure that the connections to the sensor are clean and not faulty or broken. Secondly, check to be sure you replaced the correct sensor as there are two camshaft position sensors in some applications. If you need further help with this, please reach out to us here at YourMechanic as we are always here to help.

how can i get replacement keys for the mechanical key blades attched to the 2 remote control keys of my ford explorer 2014 model
ANSWER : Unfortunately, the only way to get a replacement Intelligent Access key for your vehicle is from the Ford dealer. The keys will need to be programmed with an OEM capable scan tool as well, before the vehicle will recognize them.

Charging 14 volts and drops to 11 volts then back and forth
ANSWER : This is most likely caused by a poor connection to the voltage regulator or the alternator. Try to lightly wiggle the alternator wires all the way from the battery to the alternator and regulator connections to see if you can get the voltage to jump when a connection is moved. If none of this works then you may have a defective alternator with a loose solder joint inside it. If you need help with this, a technician from YourMechanic can come to your car’s location to pinpoint the voltage issue and let you know what repairs are appropriate.

The engine of the car runs, but when I push the gas pedal it does not accelerate, and the engine does not rev.
ANSWER : Hello. It sounds like you may have an issue with your throttle position sensor. This sensor sends a reference voltage to your power-train control module, which uses that to determine ignition timing and fuel trims. If the power-train control module is not detecting the proper signal from the throttle position sensor, the engine may not accelerate properly. It’s probably a good idea for you to have a professional mobile mechanic come to your location and complete a car is slow to accelerate inspection first, so they can pinpoint what is causing this issue to occur and they will recommend the right repairs be completed.

Key will lock doors and trunk, but not unlock doors on 2004 BMW 645Ci
ANSWER : Hi there. The first thing I would do is try another key to see if you get the same results from the key control. If the separate key works, then it is the key that is the problem.

If not, then I usually start by reprogramming the receiver module first. If that does not help, then the module may need to be replaced.

As for the window, if a window will go down and not up then the left actuator is bad. It takes more effort to close a window, so a failing actuator cannot close the window. If you need to have this repaired, consider YourMechanic, as a certified mechanic can come to your home or office to diagnose your door locks and windows so that you can have the correct repairs done.

Honda Pilot engine misfire when cold out and engine running warmer than usual?
ANSWER : Hi There,
It sounds like you may have a faulty coolant temperature sensor. This sensor relays the temperature of the coolant back to the ECM which uses this information to control many things such as when to turn the coolant fans on and off as well as how much to adjust the air to fuel ratio in the motor. Both of these functions are affected when this sensor is not working properly. If the senor is reading incorrectly, this may cause inaccurate temperatures to be read, thus causing inaccurate adjustments to be made to fuel and to the operation of the cooling fans (i.e. staying on too long or not coming on soon enough to help keep the motor cool). I would recommend having a professional from YourMechanic come to your location to diagnose and inspect your vehicle.

If I replace the ignition switch, can I use my existing BMW Keys with remote and valet key?
ANSWER : Yes, you can. The ignition switch is separate from the EWS system, so replacing the switch will still allow you to use the current keys you already have. Only if you have to replace a faulty key or EWS module will you have to possibly order all new keys.

One other possibility is there is an EWS issue where the key is not being properly identified not allowing the starting sequence. This would mean ordering an EWS module or keys from the dealer. Try out all keys you have to see if any will commence in the starting sequence. If none of the keys will start the vehicle, faults should be checked to ensure there are no EWS key identification faults. If no faults are present, then most likely the ignition switch is faulty. If there are key identification faults, then it’s either a key, module, or receiver that is the issue. You may want to consult with a mechanic who has the equipment to read out the Powertrain and EWS fault memories before replacing parts.